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Diatomaceous earth for seed starting?

Posted by Ohiofem 6a Ohio (My Page) on
Tue, Feb 4, 14 at 10:34

I've been reading about using Diatomaceous earth for tomato seed starting on another forum that shall remain unnamed. Many people reported good results, with faster and better germination than they had with traditional seed starting mixes.

But the general consensus was that some DE, including NAPA Auto's Floor Dry #8822, has a pH of 6.0, which is a little too acidic for seed starting. The best results were from using Auto zone's Ultrasorb, which has a pH closer to 6.8. A few years back I used Turface to start broccoli seeds. It worked pretty well. I am wondering if anyone has experience using any of these for starting seeds.

I've been using the NAPA product in my gritty mix (as a substitute for Turface) and in some of my 5-1-1 for veggies in fabric containers (as a substitute for perlite when I want more water retention). I have several bags and am thinking about trying it out for my veggie seeds this year. I'd appreciate hearing what others think of this idea.


Follow-Up Postings:

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RE: Diatomaceous earth for seed starting?

It works very well.
On a couple Facebook gardening groups, my friends have been using it since last year. Just recently saw what is probably damping off...so it isn't a perfect start, but it seems to work better than most potting mixes. Clean, lightweight. Works for rooting things like tomato suckers, as well.

Josh


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Tue, Feb 4, 14 at 17:34

As far as I know, calcined DE has very close to a neutral pH, but even if it was 6.0, how could that be a problem? Doesn't make sense ..... unless someone is worried about the Al content in the DE, and I wouldn't think that would even begin to come into play until the pH got to be around 5.2 or so. Why did they think a pH of 6.0 was too low for starting seeds?

Al


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RE: Diatomaceous earth for seed starting?

I don't really know why, but the person who started the long, ongoing discussion about using DE two years ago seems pretty sure about what veggie seeds need. He said:
Just keep in mind the PH is critical to good seed starting for most of the veggies we grow. Commercial seed starting mixes are balanced out to a target PH of 6.5-7.0 for that reason.

I never heard that before, which is why I came to the forum I trust to ask about it. If you two don't see a problem, then I am reassured. I am going to go for it. I'll report back.


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RE: Diatomaceous earth for seed starting?

Ohiofem,

Yes please, keep us posted on how this works. I'm curious about this method. I've never used DE for seed starting and would like to hear how it works for you.

Thanks.

TYG


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Tue, Feb 4, 14 at 19:18

I always use either the gritty mix or 5:1:1 for seeds. I just cover them with a layer of peat or Turface fines. I've never had a "pH" problem (because I've never had ANY problem), even after covering seeds with unlimed peat.

Al


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RE: Diatomaceous earth for seed starting?

Indeed.
I really like a bark-based mix (screened 5-1-1) for my pepper and tomato seeds, and I assume the bark keeps the pH fairly low. My seeds come up without issue.

Josh


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RE: Diatomaceous earth for seed starting?

Ohiofem, I would not take much advice from that person. The pH of ProMix, perhaps the most popular commercial mix, is 5.5-5.9. Any seed I ever started in it has done very well.

Remember to check the alkalinity of your irrigation water--it's crucial. Do you need to add acid?

Marc


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RE: Diatomaceous earth for seed starting?

Does anyone knows how I can use DE in seed starting mix? What exact proportions?


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RE: Diatomaceous earth for seed starting?

There is no definitive recipe with exact proportions. Many people who have posted about it on other forums have used 100 percent DE while others have mixed it with other ingredients like peat moss or bark. As Al mentioned, one recipe that works well is gritty mix, which can be made with DE. Read about it here.

I have made gritty mix with one part each granite grit, pine bark fines and NAPA Floor Dry (which is DE), and used it for seed starting. What intrigued me about using 100 percent DE is reports that seeds growing in DE can be bottom watered with little risk of over saturation. Real gritty mix is not made to wick water into a pot, although I suppose any mix will if it's left to soak long enough. When I started seeds in gritty mix, I found it a little tricky to water tiny seedlings from the top without knocking them over. It worked best for larger seeds.

You'll find a lot of recipes and discussions if you Google "diatomaceous earth for starting seeds."

Here is a link that might be useful: Search on Diatomaceous earth for seed starting


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RE: Diatomaceous earth for seed starting?

Thphank you Ohiofem.


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RE: Diatomaceous earth for seed starting?

I have a couple questions, does DE decrease the possibility of damp off? Does anyone know the ideal particle size to use for seed starting? I have been told coarse, but coarse if relative to avoid being to technical is it about 1/8 dia. or is it about 1/16 dia particles? or something different?


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RE: Diatomaceous earth for seed starting?

As Josh said, you could experience damping off, as is possible with any substance that is not sterile. The discussions I've read refer to calcined DE products like Autozone's Ultrasorb or NAPA's Floor-Dry #8822, with a size between 1/16 and 1/8 inch. This is not food grade DE or the stuff used to kill insects, which is powdery. I am only speculating since I have never used it for seed starting myself. Follow the link I provided if you want to find out what people using it say.


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RE: Diatomaceous earth for seed starting?

Josh must be greenman28, I did go through the link that you provided, didn't appear that any real study has been done other then using it as an amendment, I have some screenings of an EP product oil sorb that is in the 1/16 and a 1/8 particle size I will just try the two sizes and see if there is any noticeable difference in seed starting between the two. I have read the info you guys have provided about the food grade DE and will avoid using it, I was assuming that damping off needed some type of plant material to grow on which would be typical of a standard starting mix with a peat content, but it stands to reason that as soon as your seeds sprout you have plant material for the fungus to grow on. Thanks for you input.


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RE: Diatomaceous earth for seed starting?

I don't know if anyone is still fallowing this thread, but just an update I started 216 seeds using DE, from the info Ohiofem referenced it is important to place a small piece of coffee filter in the bottom of the seed cell otherwise the DE will fall through, I think anything that will allow the DE to wick will work, I used coffee filter, I have other starting media but this DE was something that I came by for free so instead of using my more expensive mix I gave this a shot.


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RE: Diatomaceous earth for seed starting?

Great. What did you plant? Are you growing under lights? Please keep us informed. I won't be starting any until March 1, when I will start peppers on heat mats under T5 lights.


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RE: Diatomaceous earth for seed starting?

I started Pheonix tom, Sioux tom, Hawaiian pineapple tom, Super sweet 100 tom, Super Marzano tom, OK now don't leture me but I found some experimental tom seeds from Monsanto I dont know what they are for sure but we will see, also Serrano peppers, Bell peppers, and some english daisys. I am growing under some T8's that I have over driven they really put out some light. I have bottom heat on these, I just backed up 10 weeks from my last frost date may 15th I think should be the same as yours Ohiofem ? I initialy screened my DE over a 12 mesh screen, not knowing the ideal particle size I used the +12 particles to start the seeds in, and lightly covered with the -12 screenings. I have no idea if this is the proper approach or not but will find out.


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, Feb 16, 14 at 12:53

Please keep posting your results to this thread, guys. I'm sure it will be pulled often via the search function, so others will still be able to find value in it long after it drops off the screen.

Al


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RE: Diatomaceous earth for seed starting?

Stimey: we could do a whole thread about timing for planting seeds and setting out plants. (And it has been done many times, I'm sure.) My last frost date is May 5 according to greenthumbweather.com, which means there's a 50 percent chance of frost after that. So I don't usually plant peppers out until the third or fourth week of May. I like to grow peppers about 10 weeks before planting out, but I prefer to grow tomatoes for only six weeks before planting out. In both cases, that timing produces plants that are about 12 inches tall when going into the garden. They get leggy if I let them get much bigger than that. I'm going to try to push the season for some of my heirloom tomatoes that take 85-90 days to produce by setting them out in the last week of April with wall-o-waters. But I won't start them until March 15. It's darn hard to wait, though.

Here is a link that might be useful: Seed starting chart


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RE: Diatomaceous earth for seed starting?

I have had anxiety all my life, its a thorn in my side, I seem to always start to early, your correct we could start a new thread on the subject, it has been done multiple times. Correct me if I am wrong but you can have to large of a transplant and not gain anything, I have done this with the theory you can plant them deeper and have a better root system I don't see it working if you are supplying the needs of the plant anyway. You know I have some 100 day toms that I really want to get to set fruit before the heat hits, have you had good results with the wall o water? It sure is hard to wait I agree, I have some friends at work that want those really large transplants so I try to fulfill there wants even though I think the 12" transplant don't set back as bad as the larger ones and soon catch up, and sometimes pass the larger transplants. I would love to get these Hawaiian pineapples to set fruit they are not a big producer, but are suppose to have that fruity taste.


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RE: Diatomaceous earth for seed starting?

I think you can germinate seeds in a lot of things, including air( in a glass jar). But in general if I am going to germinate it in a medium, that medium has to have particle sizes smaller than the seeds for optimum moisture retention and subsequently root growth. A hairy root cannot easily draw moisture from some chunky pieces, in a medium with a lot of air pockets. That is why I BELIEVE in peat based starter mix with vermiculite(retain moisture longer) and perlite ( provide drainage of excess water). Once the seeds germinate and have a few sets of leaves, then there are many re potting mixture options.

JMO


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RE: Diatomaceous earth for seed starting?

seysonn that is the best answer to a question I have asked several times, "what particle size for DE seed starting" that is very thought provoking, I know there has to be some air but those brand new roots off a seed can be very small. Peat base with vermiculite, I have never used that for seeds but do see how that would be much better then this stuff I got from MG, with that said I went into my local nursery last Friday to pick up a large bag of ball pro mix, my main contact there told me he was glad I didn't come in last week to get it cause they had received a bad shipment and this batch was much better. It may be the bag of MG starting mix I got just slipped through QC Thanks for you input I may screen some of this DE smaller


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RE: Diatomaceous earth for seed starting?

New roots are tiny on a mighty oak tree that is 100 years old just like they are on a new tomato seedling. I am going to try the NAPA Floor Dry with particles in the 1/8 inch size range because I have been unhappy with how the seed starting mixes made primarily of peat moss compact during seed growing. It starts out fluffy but sinks down and becomes compacted over time. Seed roots need air as well as moisture, and I am hoping the DE will provide both without compacting. Let's take photos of our different sized mixes as we go along to compare how they hold up.


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RE: Diatomaceous earth for seed starting?

Most folks using DE are using it straight out of the bag, no screening or sizing at all. It is lightweight stuff, and roots have no problem moving through it. It also holds enough moisture that new roots won't dry out.

Josh


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RE: Diatomaceous earth for seed starting?

Wouldnt it retain too much moisture, isnt it like vermiculite in texture/water retention?

How much is DE? I would think it would cost much more than most mediums..


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RE: Diatomaceous earth for seed starting?

This is the stuff I am talking about. The texture is like turface or gravel, nothing at all like vermiculite. It holds six times its weight in water, but it doesn't collapse.

I think I paid about $8 for that 25-pound bag, which holds almost 2 cubic feet. It's cheaper than perlite or sphagnum peat moss around here. I'm at work, so I can't measure the particles, but I believe they are around 1/8 inch in diameter. This product is used by bonsai growers. Follow the link below if you want to know a little about the advantages of DE.

Here is a link that might be useful: Cat Litter (DE) as Bonsai Soil


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Feb 17, 14 at 16:48

If I wanted to use calcined DE exclusively as a seed starter, I think I would screen it over insect screen or use a "regular" size kitchen strainer, reserve the fines, spread the seeds on top of the screened mix and cover with 1/8" of fines or mix the seeds in with the fines and sprinkle the seed+fines mix over the screened DE and THEN cover with more fines. Confused yet? ;-) ..... and water via mist until the seedlings are established.

If seysonn's idea that soil particles need to be smaller than seeds was accurate, the only thing you could start a number of small seed varieties in would be pudding. Seedlings appreciate the same soils that mature plants like. They only need a little extra care initially to be sure they're not dislodged by overzealous watering.

Al

This post was edited by tapla on Mon, Feb 17, 14 at 16:54


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RE: Diatomaceous earth for seed starting?

Thanks Ohio! I was thinking of the DE that is powdered to kill insects. Now it makes sense...

Thanks to you as well, Al! You are always a wealth of information!


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RE: Diatomaceous earth for seed starting?

I think there has to be a co relation between the seed size and the particle size in which the newly germinate seed has to grow and draw nutrients from. The example of a 100 year old oak tree is not relevant, b/c that oak has miles of roots and most of them are covered/immersed in fine moist soil. A new emerging tender seedling does not have the 100 year oak tree's capability.

In order to understand it , lets take it to some extremes: Can you grow tomato seedling in rocks the rough size of a softball? If your answer is "yes" , Then stop reading because I cannot continue this discussion with you. But if your answer is "NO", then can you grow it in rocks the size of pin pong ball? Still probably "NO". we have to reach a point that we can say "YES" that is the size. How do you get to that size, and by what logic ? I like to know the answer.


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RE: Diatomaceous earth for seed starting?

Exactly what seysonn said, Talpa talked about some of the seeds that are so small that the substrate would be pudding and I agree. As well as particle size is obviously an issue so is water quantity within that substrate that is made up of many particle sizes, with that said we are talking about DE as a seed starter made up of all particles relatively the same size if screened. If we match particle size to seed size, should we not also match water quantity? would this help with the pudding issue? Now if we make that particle size to small we have another problem just as if we make the particle size to large, we know that there is probably a expectable range per seed size, question here has there been any documentation done to confirm the ultimate particle size per seed size? Are we just working from tribal tradition, e.g. this has always worked good for us! Is a study in order? probably has already been done. I agree with the question what is the ideal particle size? I deal with particle sizing on a daily bases for varying reasons, and I feel in this situation it is a valid question, I also think that the applicable particle size of an exceptable substrate is probably a fairly broad range.


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RE: Diatomaceous earth for seed starting?

This discussion is not about speculation over an ideal correlation between seed size and particle size. It's about using DE of a known size (between about 1/16 and 3/16 inch wide) with seeds of various sizes. It so happens that I plan to try it with tomato, pepper and eggplant seeds, which are in the same size range. But, today I decided to start with tiny basil seeds.

This photo is made up of two different shots. At the top there are basil seeds on the left and soaked DE in a four-cell nursery container on the right. The lower photo is a close up of the black basil seeds mixed into the material I screened out of the DE. (By the way, there was very little to screen out.) Since the seeds are so small, I found it easier to mix them with the DE to sprinkle on top of the seed cells. I sprayed the top of each cell with water, covered the container with plastic wrap and placed it in a warm (75F) room. IIRC, it takes 5-8 days for basil to sprout under ideal conditions. We shall see what happens.


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Thu, Feb 20, 14 at 15:44

If you dared me and made it worth my while (made it a bet), I'd illustrate that tomatoes can be grown from seed in a bucket of broken glass or marbles.

You're familiar with how fine leaf lettuce seeds are, right? .... about like ground pepper or sugar crystals. I have 3 plastic planters that are 10 x 36 x about 8" deep. Every year, at about 3 week intervals, I fill one of them with very coarse 5:1:1 mix to about 1/2" from the top. I mix 1/4 tsp of seeds in about 1/2 cup of Turface fines and sprinkle the seeds over the top of the soil. They go in the shade out of wind & get misted daily until they germinate, then they go in the sun or part sun, depending on the date. If I was planting oak trees, I'd follow pretty much the same plan - use the same soil, but skip the Turface fines.

If we consider what we'd be growing in if our soil particles had to be smaller than our seeds, we'd be growing lettuce in a soil that supported several inches of perched water, and we know the lettuce isn't going to like that. With a little attention to detail, you can start your seeds in a mix that's going to support a healthy root system for the mature plant ..... and if you are using a really good soil, you can plant your annual seeds or seeds of perennials grown as annuals in a container large enough that transplanting won't ever be necessary.

I use the 5:1:1 mix or gritty mix to start everything I grow from seed - have been doing it since the soils were conceived and without variance it's worked extremely well.

All you need to start seeds is a soil that when the plant is mature you can water properly. Remember, the seed gets almost all it's nutrition from the cotyledons within the seed, which are the major storage tissue and the embryonic plant's source of energy during the first days of the radicle's (tap root or main roots) and subsequently developing hypocotyl's growth. Once the seed radicle is established in the medium and the plant has light exposure, the plant will begin to draw on nutrients from the soil and light energy to fuel growth. Most of the plant's stored energy will initially be devoted to growth of the radicle (it grows FAST). Once it is established and a vascular connection to the top of the plant is formed, the plant is on its way. All that is actually needed to get the plant to this point is water and oxygen - you don't really even NEED a soil to get this far; so even though you wouldn't WANT to start plants from seed in softball size rocks, you certainly could if you wanted to press a point.

Al


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RE: Diatomaceous earth for seed starting?

Cool Ohiofem looking forward to see how it comes out, I too have some stuff going using 1/8 particle size with 1/16 over the top of the seeds. Well said tapla I agree, Like I said the study probably has already been done, and proved. Now that you show that and we are talking about starting seed that is going to be transplanted shortly after germination it makes as the sense in world. Another thought provocation, thank bubba.


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RE: Diatomaceous earth for seed starting?

Wow sorry about my last post, I thought I was awake this morning when I wrote it.


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RE: Diatomaceous earth for seed starting?

Just an update, my seed germination has been very poor, the ones that did germinate had the seed coat stuck very hard. I am wondering if maybe some of the issue may have been evaporative cooling, my process was the same as I have done with peat base starting mix, I just wonder with the particle size of the DE being larger then the peat base mix, it allowed the evaporation cooling to be more prominent? Or did I over water since I watered the same as I would a peat base mix.? I maintained bottom heat at 78 degrees give or take 2 degrees, my temperature probe was near the bottom of the mix so I wouldn't of noticed if there were a lower temperature at the seed zone. I had one evening I lost power, when I found this out the seedlings had dropped to 64 degrees. My seed supplier asured me that the seeds were not old, that was my first thought when the seed coat was stuck on every seed that germinated. What do you guys think?


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RE: Diatomaceous earth for seed starting?

Did you have a dome over the seeds, or plastic wrap to maintain moisture/humidity?

Josh


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RE: Diatomaceous earth for seed starting?

Some of my basil seeds have sprouted, and I don't see any with "helmet head." It's been one week since I set them in the DE, and I see at least six sprouts in this cell. I'm sorry that I didn't count them when I planted because I was in a hurry, but I would guess there were about 10-12 seeds in this cell. These seeds were purchased a year ago, so I didn't expect them all to sprout.

I set them in water for up to five minutes at a time every couple days to water. I have a sheet of Cling Wrap loosely lying on top of the cells and the container is under T5 lights in a room that is between 68 and 75F. I'm not using a heat mat, but I plan to use one under my pepper seeds. I like that i can leave them in the water, and the mix doesn't get soggy or compacted. I will admit I was getting nervous when I didn't see any signs of life at 6 days, but now I am reassured. I'm planning to keep the plastic wrap on them until the stems elongate and seed leaves open completely, then I will remove it.

I'm probably going to wait 5-7 days to start my peppers to see how these do with the plastic removed. I have a vaporizer in the room, but I can't raise the humidity much above 35 percent.


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RE: Diatomaceous earth for seed starting?

Lookin' good!

Josh


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RE: Diatomaceous earth for seed starting?

@ Ohiofem,
Of course I see your basils are sprouting through the chunks (relatively speaking) of DE. But what is the point to make them to work their but off to push though all that?

Al, suggested screening DE through insect screen. That makes more sense to me . We want to create the most favorable condition not to challenge the seeds to their extreme. When I said that soil particles should be smaller than the seeds, maybe it was a bit off. But lets say twice the size of seeds. Isn't that why conventionally recommended to covered seeds with a thickness of about TWICE the size of seed ? How can you do that with mustard seeds and Floor Dri with chunks as big as 1/8" or bigger ?

Lets just say that I have a hard time digesting it and you might be right.


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Feb 28, 14 at 16:52

I think conceptualization can be a very useful tool. That's how I decided how to go about making the gritty mix and what to use. So let's conceptualize for a moment about what the perfect seed starting mix would be. I'll start by describing mine, and you guys see if you can improve on my concept. I hope I'm not pushing the thread in a direction you didn't want it to go, Robin.

First, I wouldn't care about the soil providing nutrition - that's what the cotyledons and subsequently, fertilizer, is for. Second, I would want the soil particles to be large enough that they don't support perched water - which means they need to be about .100" or larger. Third, since the soil particles will be too large to support water in the air spaces between the particles, the particles need to be internally porous with open pores so they serve as water reservoirs. It would also also be nice if the particles held nutrients reasonably well.

So how would we go about implementing that concept? One very good way is to do exactly what Robin did. Use screened DE. I actually think it's a better choice than screened Turface because the particle size runs a little larger. Turface screened over insect screen is still small enough that it will hold a little perched water if used. If she happens to encounter any setbacks (probably won't - she knows what she's doing and how to build a good medium) between now and planting out, I seriously doubt they would be related to her choice of medium - just because the concept is so sound.

Al


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RE: Diatomaceous earth for seed starting?

Seysonn: You made me laugh at the idea that my poor basil seeds are working their tiny butts off. Maybe that's a good thing if it leads to muscular plants.

Al: Thanks for the vote of confidence. Just to clarify, I screened the DE using a kitchen strainer so the holes were about the size of insect screen. I used the "big" stuff in the container and mixed the stuff that passed through the screen with the seeds to sprinkle on top. There wasn't much of the "small" stuff, so some of the seeds weren't covered. When I grew them in standard seed mix before, some of the seeds weren't covered either, and they sprouted fine. I've had more problems when I buried tiny seeds too deeply than when I let them peak through. I think I should bury larger seeds like peppers and tomatoes a little more. Some seeds, like lettuce, benefit from a little light, but I don't think that's true with peppers and tomatoes. I may add a dusting of milled sphagnum moss on top if I don't have enough of the small stuff from screening the DE.


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RE: Diatomaceous earth for seed starting?

greenman28 I used domes over my seedlings until I seen the first seeds sprout and then removed the dome. Does anyone know what mesh the above insect screen is?, or what is the micron size? I have inquired about this several time but no answer, I am pretty sure my issue with the poor results on seeds were temperature and old seeds, with the seed coat stuck so hard on every germinated seed led me to believe the seeds were old, the supplier assured me none of there seeds are old stock. I had seeds from the same company that done just fine germinated in 5 days on two different variety's of toms, and peppers, but the toms in question took 14 days to show any sign of germination, I reordered after speaking with my supplier so we will see on my next try. I see if you read multiple threads through out gardenweb on this subject there are a number of contradictions made by the same members, I assume this is a product of learning as you go?


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RE: Diatomaceous earth for seed starting?

Insect screen is typically 1/16 of an inch.

I "water" my seed-starting mix with a spray bottle, which moisten the upper layer and any seed-cases that might be stuck.

Josh


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RE: Diatomaceous earth for seed starting?

Talpa stated: ("I would want the soil particles to be large enough that they don't support perched water - which means they need to be about .100" or larger.") .100" is about a 7mesh screen, 1/16" is .062" about a 12 mesh. Now with my failure I spoke of earlier the seed coat was completely covering the cotyledon there wasn't any green showing on any of the seeds. Initially I watered from the bottom to wet the DE prior to placing my seeds and lightly covering with a -12 mesh screening so .110" and smaller. I don't think particle size played into my issues unless it had something to do with the evaporation affect that I spoke of earlier, I do put a pencil on one edge of my dome to help with air flow. I never seen the DE dry during the 14 days it took to germinate, if anything I probably watered to much with the initial bottom water and then the daily light misting. With that said I don't know what affect to much water has on seeds at 78 degrees. Talpa your the Guru, whats your thoughts? When I seen the seed casings stuck I assumed shortly I would see green cotyledon, never did in fact the seedlings today are almost an 1/2 inch tall with the seed coat still covering the cotyledon. I might try to get a pic tomorrow, I done pulled them off the heat mat but haven't throwed them out yet, its 11 degree right now and going down, that trip form house to greenhouse is not very fun right now. Greenman28 thanks clarifying insect screen size. Any input is welcome thanks.


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RE: Diatomaceous earth for seed starting?

Stimey: I think higher humidity can help prevent stuck seed shells, but some seedlings, especially peppers have a greater problem than others. They talk about this in the hot pepper forum. I think the DE I am using has a larger particle size than your stuff. I don't see how you could water the NAPA Floor Dry too much. That's one of the reasons I like it. Dryness is death on sprouting seeds. I've been setting my containers to soak in an inch of water for 5-10 minutes every day and also keeping them covered with plastic wrap. You might get some ideas from this other discussion.

Here is a link that might be useful: Seedling sprouts with Seed still attached?


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RE: Diatomaceous earth for seed starting?

Misting the seed-cases should soften them sufficiently to where you can apply cross-pressure and slip them off with a pair of tweezers. Mist them, wait five minutes, then gently attempt to slide the case off. If the seed-case resists, mist again - be sure there's a bead of water attached to the case - and try after a few more minutes.

Josh


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RE: Diatomaceous earth for seed starting?

Thanks for the link Ohiofem that was some good info, after reading that link I may have planted to shallow also. From what you indicate soaking your trays 5-10 minute daily, I definitely did not over water, I do know that my DE was always wet just by the color it is very easy to tell, dry it is white, moist it is light brown, I misted daily until about the 12th day when I was worried that they might be to wet. I also wondered you guys use napa DE and I was using a EP minerals DE, this same product that is used as spill clean up is also used as hydroponics grow media according to there web sight. Oh well we will just try again, I received another email from my seed supplier indicating that the super merzano seeds was last years seed, but all others were fresh, it is what it is, I am still having fun so alls good. Thanks


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RE: Diatomaceous earth for seed starting?

I find DE to be an excellent product. Not just for seed starting. It is an excellent soil amendment. I thought it may be like turface, but it is nothing like turface. Which is a huge plus for me. Glad I looked into it, I'm sold on DE for sure.
http://www.sciencedirect.com/science/article/pii/S0341816211001615

http://www.sciencedirect.com/science/article/pii/S0341816212001841

http://scihub.org/ABJNA/PDF/2010/5/ABJNA-1-5-1076-1089.pdf

http://www.axisplayball.com/home_htm_files/AXIS for POTTING SOIL.pdf


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Mar 5, 14 at 9:24

You sure are an easy sell. ..... sold on pumice w/o having tried it ....... dead against Turface w/o having tried it ....... Have you ever tried calcined DE, which IS a lot like Turface - with some minor variance in water retention, CEC, and pH?

Al


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RE: Diatomaceous earth for seed starting?

I admit I'm easy. DE seems to be superior to pumice. I have used pumice for decades, but it's been decades since I used it. I use to use it in mineral mixes in the 80's for cacti. But I don't remember what percentage, etc.
I prefer scientific studies to determine if it's worth trying.
So far turface keeps finishing last. I'll take their word for it, instead of going through the school of hard knocks.
The probem I have with turface is the pore size. Pumice is too big, you would need a lot. Turface is too small, and it's not useful, as it tends to retain the water when it's needed.. Seems DE is just right.
You know if it's not broke don't fix it, if turface is working for you great! Keep using it! Turface may work for me yet with cacti. I kinda want something that will not give up water easily. I will try it this summer.

This post was edited by Drew51 on Wed, Mar 5, 14 at 10:12


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RE: Diatomaceous earth for seed starting?

Al (Talpa) if you have some time could you tell me your thoughts on a 5-2 mix, 5 parts of 3/8 particle size pine bark, and 2 parts screened DE? I have not put this in a container yet but have mixed and limed it, I wet it as I mixed it, I believe it was greenman28 that gave me some directions on how he mixes 511, at any rate my question is do you have a feel if I am going to have a PWT? It really has been retaining moisture for a good period of time since mixing, the top drys out but 2" down it has been remaining moist, I used moderation when I wet it to ensure I didn't over do it, looking forward to your opinion, thanks


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RE: Diatomaceous earth for seed starting?

I searched and came up with another thread right in GW, about DE product, namely Oil Dri.

It has been baked, soaked, frozen, thawed, ... it has maintained its structure.

NOW I am doing my own investigation.
I bought a bag from O'Reilly ( 25lbs for $9). I was looking for small quantity to use for pest control. They had 5 lbs for $6 and 25 lbs for $9. Duuhhh

Anyway: First I weighed a CUP of it. It came to 110 grams. Soaked it in water for several hours (did not soften or fall apart).
Strained it ; It weighed almost 220 grams: = 100% absorption by weight.

Right now I am freezing some. I will report the out come later.

Anybody knows specific gravity and absorption rate of Turface?

Here is a link that might be useful: oil dri


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RE: Diatomaceous earth for seed starting?

Oil-Dri sold by O'Reilly Auto Parts is clay, not Diatomaceous earth. It is comparable to Turface. There is a discussion of the qualities of both here:
http://forums2.gardenweb.com/forums/load/contain/msg090913029810.html

Some packages of NAPA's product were called Oil Dry and the ones I have been using are called Floor Dry. In either case, the product number is 8822.

Now, can we please go back to discussing seed starting in DE and take the off topic discussions to their own threads?

Here is a link that might be useful: Turface vs. NAPA


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RE: Diatomaceous earth for seed starting?

Oil-Dri sold by O'Reilly Auto Parts is clay, not Diatomaceous earth
*********************************
I think its said on the bag "100% DE".
I will check it later.


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RE: Diatomaceous earth for seed starting?

From the O'Reilly website: Oil-Dri Premium absorbent clay granules are used to absorb most types of oils, mixtures of soluble oils, acids, paints, inks, water and other liquid spills.

O'Reilly also sells two DE products--UltraSorb and OptiSorb--which some have used for seed starting.

Here is a link that might be useful: O'Reilly absorbent prtoducts


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RE: Diatomaceous earth for seed starting?

O'Reilly also sells two DE products--UltraSorb and OptiSorb--which some have used for seed starting.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Ohiofem,
Now we are talking. What I bought is ULTRASORB, 25lbs bag for $8.49 + tax . As I mentioned before, my purpose/application is to use it on pests (slugs etc) so i wanted to make sure that it is DE.

UPDATE on freezing:

I soaked it in water and then froze it for several hours ; Took it out and thawed it. Did NOT change(visually) nor fell apart. It is not as hard as granite or gravel. I can crack it with my finger nail. But I think it is normal, b/c it absorbs a lot of water (100% by weight).


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Thu, Mar 6, 14 at 7:11

That's not what you want to use as an insecticide. You don't want a calcined product for that application - you want the DE in dust size.

Al


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RE: Diatomaceous earth for seed starting?

Al is right, I think the food grade is dust too. You coud use the dust from this product. It will work, or maybe crush the product? Some other notes OptiSorb is larger grain size.
UltraSorb is probably best for seed starts. It does reduce damping off. The fungi need organic material to start, and this is inorganic. Other users I know say it has eliminated damping off for them. Worth trying in humid areas.
RayR did an experiment with peppers here is UltrSorb vs. Jiffy


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RE: Diatomaceous earth for seed starting?

Another photo looking at roots.


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RE: Diatomaceous earth for seed starting?

I know one guy who just uses DE as a growing medium.
The pepper 'Tricolor Variegata'


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RE: Diatomaceous earth for seed starting?

This is what I have been using, it is 100% DE
http://epminerals.com/products/diatomaceous-earth-2/diatomaceous-earth-aggregates


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RE: Diatomaceous earth for seed starting?

That's not what you want to use as an insecticide. You don't want a calcined product for that application - you want the DE in dust size.

Al
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
USING DE AS PESTICIDE:

#1: Actually for one of my applicatins (Fighting slugs) I want fine grain size. This has two advantages : ONE: it will not be washed out readily. TWO : the rougness would tear slugs' belly OR they will just avoid it.

#2: Where can I get it in dust form ? I can always pound , grind it. Does calcination change its property as insecticide ?

DE in CONTAINER GROWING APPLICATION:

After actually seeing this product (Ultrasorb DE) I have come to like it. Maybe I won't use it straight, but I will mix it with screened pine fines for repotting my seedlings. It is like double edged sword : One, it hold good amount of moisture and TWO: it will drain excess water and provide aeration. And the thing is that it is not very heavy. A cup (soaked )weighs about 200 grams. So its bulk density (soaked ) is about 0.9 gr/ cm^3, That is lighter than water. Of course it has a lot of micro cavities. That is why we deal with its BULK density rather than specific gravity.


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RE: Diatomaceous earth for seed starting?

Another thing I like about DE is that it should last a very long time. I want to recycle potting mix, so vermiculite does not last long at all, perlite lasts for at least 5 years. I guess because it was heated and popped, it does break down. So like pumice, this stuff will last and last. As I want to recycle the potting mix into the garden as compost. I doubt even if it breaks down perlite and vermiculite will hurt, but DE will increase the gardens' water retention and aeration so it will actually help the garden. For decades if not longer.
So I'm thinking of replacing perlite with this stuff in my potting mixes. It's not expensive either, it's all good!

I also think if you crush it you will have the same material used for pest control. Yes it is the same stuff, and will work.
If you wish to pay more for somebody to crush it for you I guess that's OK? Kinda like buying pre-chewed food, no thanks, I think I'll do it myself.

Another benefit not mentioned is the powder in the mix makes silicon available, a trace mineral that is essential.
So it aids in water retention, aeration, and nutrition. This stuff rocks! Kills bugs too, jeez, this is an excellent product!


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RE: Diatomaceous earth for seed starting?

As I recall from my organic farming days, it's the individual needle like diatom skeletons in DE that kills pests by piercing or abrasion, leading to dehydration. Insecticide grade DE has been mined, processed, and handled to minimize damage to the individual microscopic glass-like skeletons. I used to buy insecticide grade DE in 3 cf bags and I recall it being ultra fine and almost fluffy. I suspect DE that's been melted in a furnace then smashed into dust wouldn't have much, if any, value controlling pests.


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Thu, Mar 6, 14 at 16:49

It is widely reported that DE pierces insect skeletons and causes them to dehydrate; actually though, DE causes desiccation in insects by absorbing the oils and fats from the cuticle of the insect's exoskeleton, after which they dry out. Its sharp edges are abrasive and only help speed the process. DE remains effective only as long as it is kept dry and undisturbed. I agree that calcined DE would probably not have much insecticidal value.

So let's get back to talking about seeds!

Al


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RE: Diatomaceous earth for seed starting?

So let's get back to talking about seeds!

Al
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Alright. You've got a reader.


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RE: Diatomaceous earth for seed starting?

I agree lets talk about seeds, 1. Can you over water when starting seeds with DE? 2. Can a 3/16 particle size of DE cause evaporation cooling to be detrimental to germination? 3. Talpa if you will answer my question, you stated before that you use a screened 511 to start your seeds, do you feel that is a better approach then straight DE? 4. Can a person use a fungicide misted over the seed tray to battle damp off?


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RE: Diatomaceous earth for seed starting?

Screened 5-1-1....it might have been I who mentioned it, Stimey, although I know Al uses both the 5-1-1 and Gritty Mix for seed-starting. This is a gritty 5-1-1, screened, using Turface (a little red lava rock, too), and no peat/potting mix.

Josh


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RE: Diatomaceous earth for seed starting?

Here's an update on my basil seeds planted on Feb. 20 in diatomaceous earth. They look healthy, but it seems to me that their growth is fairly slow. I am bottom watering everyday with distilled water that has about 1/8 teaspoon of Foliage Pro in it. I have kept them loosely covered with plastic wrap for most of the time until yesterday. They are sitting about 5 inches under a high output T5 light.

Basil seedlings growing in NAPA Floor-Dry on March 7, 2014 - Started Feb. 20, 2014:

On Feb. 21, I started some basil seeds in an Aerogarden, where they are growing hydroponically, and they are already almost an inch tall. Now these seeds may have been treated to speed up germination, but they are labelled Genovese Basil just like my other ones. The light is about six inches above the seeds. Herb growth in an Aerogarden is always impressive.

Basil seedlings growing in an Aerogarden on March 7, 2014 - Started Feb. 21, 2014:

Thoughts?


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RE: Diatomaceous earth for seed starting?

Since it has no nutrients, maybe start fertilization early. Yeah I'm doing some germination tests too. I know for some things it doesn't work well. I have pretty good luck with regular seed starting mix, so not sure I will switch. Depends on how well my experiment goes.
A mix may be best such as what Josh is doing.


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RE: Diatomaceous earth for seed starting?

Very Good. Please keep us updated.

Germinating is one thing and growing is another. Up to the stage of true leaves, seedlings don't need any help from the medium, other than moisture. But after that stage they will be growing more roots and looking for an environment in which they can get/take up nutrients. Can a granular medium with ZERO nutrients and with not much retention/storage for nutrients, can sustain the growth of small seedlings? I would like to know. What can we learn from mother nature and natural soils that most vegetation grow in them?

This post was edited by seysonn on Sat, Mar 8, 14 at 13:17


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RE: Diatomaceous earth for seed starting?

At the moment with my limited experience with starting seeds in DE I don't see a true advantage other than water retention, with a mix of DE and pine bark fines or something like greenman mentioned it seems you would get the water retention as well as a media that can hold nutrients for further growth after initial germination up until time to pot up. I just don't see the advantage of DE by itself, my initial thoughts was that it would accelerate root growth quickly due to the perocity and gas exchange? I found that the seeds that did germinate in my trial grew very slow, I removed the seedling to observe the root zone and wasn't impressed, with a smaller particle size I might have seen something different I did use a large particle size in my initial trial.


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RE: Diatomaceous earth for seed starting?

When I tried leaving the plastic wrap off my basil seedlings in DE for a day and night, some died and none are showing signs of forming true leaves yet. I think using 100% NAPA Floor-Dry the way I have is a bust. I don't think the problem is caused by particle size or the fact that DE contains no nutrients. After all standard seed mixes are often free of nutrients, and I have seen seedlings sprouted in 100% coarse perlite of a similar size with few problems.

In my case, it appears that the DE is drying out out so fast, that the tiny seedlings are drying out too. Although I have been soaking the containers every day and spritzing the seedlings with plain water several times a day, the surface of the mix dries out fast under my lights. This photo shows a seedling leaf that has dried up and is stuck to a particle of DE.

I am not going to give up completely on DE. Last Sunday, I planted six different types of peppers in two different mixes. Half of each batch is planted in the seed starting mix I used last year, which is basically Metromix 510 with added coarse perlite and milled sphagnum moss (NoDampOff). The Metromix is about 45% bark and is my favorite off-the-shelf potting mix. For the other half of each batch, I set the seeds on top of soaked DE and covered them with a 1/4 inch layer made up of a 50-50 mix of my old seed starting mix and DE. It's been seven days, and none of the seeds have sprouted yet. When they start sprouting I will report back.


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RE: Diatomaceous earth for seed starting?

I think newly germinated seedlings with very limited and thin roots require a good contact withe the medium. That is no accident that all seed starting mixes are made of finer stuff like coir, peat, vermiculite. Then they add some fine perlite for drainage. Media like straight Turface and/or DE have a lot of cavity, too much air pockets not providing enough contact surface for the tiny roots. Even play sand is better than DE or turface.
Just My Opinion.


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RE: Diatomaceous earth for seed starting?

I think you're right. If you look at the photos I uploaded the DE is pretty fine. Not as fine as food grade, but finer than UltraSorb. Maybe the bottom of the bag has finer material that would work better. Still i think a mix is probably best.


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RE: Diatomaceous earth for seed starting?

Seysonn and Drew: how, then, would one explain the success that I've enjoyed with my coarse seed-starting mix? I screen out the particles that are less than 1/16 of an inch, leaving quite a porous matrix - there are even cells where the seeds are largely exposed. With the plastic wrap, there shouldn't be a problem.

Josh


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RE: Diatomaceous earth for seed starting?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Mar 10, 14 at 16:23

I had a post written along those lines too, Josh, but I didn't post because I didn't want to come off as snarky. There's a lot of hasty conclusions being made without basis lately, and a lot of opinions being offered, in spite of the fact the individual offering the opinion has no personal experience related to the topic.

If I knew exactly what was giving Robin problems I'd be quick to jump in and help. I don't know exactly, so I'm not going to take a SWAG at it and call it good - that's the stuff myths are made of - people putting conjecture on an equal footing with facts and solid evidence.

Al


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RE: Diatomaceous earth for seed starting?

It sounds like the confusion derives from an assumption that the seedling roots require direct contact with the medium to stay moist. Granted, it's bad news if they dry out. But if the medium remains moist, and if a high RH is maintained in the space between the particles, then the roots should be stay moist even though they are in contact with air. Think hydro, or even aeroponics. Actually, the idea of bottom-watering the DE is starting to remind me of some forms of hydroponics. Now, you just need to use a dilute nutrient solution for bottom-watering...

This post was edited by maple_grove on Mon, Mar 10, 14 at 16:38


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RE: Diatomaceous earth for seed starting?

We need more input. I planted 6 peppers in pure DE, and so far so good they came up. They took a bit to come up, but they look fine so far. So who knows why the basil didn't perform well? On another forum the user had no problems with the mix with basil. I thought maybe it wasn't good because I too, didn't see any growth in the seeds I planted. I guess I didn't give it enough time? The mix seems to have worked for me so far. The next few days will be informative.
Certainly loads of evidence it works. Not only studies but many users have had good success with it, so the poor results reported were rather confusing, then my seeds taking 8 days to germinate is long by my standards, but not really long for peppers. Sometimes they take 14 days.
Good because I'm out of regular mix and about to start my tomatoes, which I will now do in DE, if all goes well with the peppers in the next few days.

This post was edited by Drew51 on Mon, Mar 10, 14 at 16:47


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RE: Diatomaceous earth for seed starting?

Now, you just need to use a dilute nutrient solution for bottom-watering...

I did use distilled water with 1/8 teaspoon Foliage Pro 9-3-6 per gallon on these seedlings for bottom watering once a day. I also used plain distilled water to spray the top of the containers a couple times a day. The basil in the aerogarden is in a hydroponic solution of 1/4 teaspoon per gallon of FP and it continues to do well.

I've noticed a couple more dead seedlings that appear almost desiccated in the DE. It may be that the diluted FP in the DE was too much fertilizer. When I made the solution I didn't think I would feel a need to use it so often, but I have been amazed at how quickly the surface dries out whenever I leave the plastic wrap off. Is it possible that the DE is sucking moisture out of the seedling? When the seed leaves dry up and stick to the DE particles, it looks like that may be what is happening.

Believe me, I didn't want to report these results after all the early predictions of failure based on speculation about things from people with no personal experience. But I feel honor bound to share actual personal experience as opposed to conjecture drawn from opinions with no evidence.

Finally, I want to remind folks that it is a violation of forum rules here and on other forums to post other people's photos without written permission.


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RE: Diatomaceous earth for seed starting?

I work with critical, cutting, snide, (Snarky) everyday, Talpa personally I would have never taken it that way, but personally I would prefer you guys to set us novice straight. Please guys anything I post I assure you is based on incomplete information due to my total lack of, or very limited experience, I come here to learn and welcome information how ever it comes across. If I get to far out on the chain you guys feel free to yank on it. From what I have read in this thread my failure on seed starting with DE has very little to do with the DE itself, with that said I see most of you folks are using plastic wrap and not a dome cover per say? Could someone expound on that please?


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RE: Diatomaceous earth for seed starting?

Stimey: You are sharing your personal experience, and I think we all appreciate that. I am a newbie when it comes to using DE for seed starting just like you. I don't think we have enough evidence yet to reach a conclusion about the cause of your problems or mine. We are here to share and learn together.

I think the product you used has a smaller particle size than the one I used. I probably watered more than you and may have used more fertilizer. Maybe there's something else we both did that caused problems, or maybe not. If more people share their experiences, maybe we can figure out what's going on. We do know that others (who aren't part of this discussion) have had success with this method, so I'm not ready to say DE doesn't work.

I usually use a plastic dome over my seedlings, but I used plastic wrap this time because I only had one small container. I think they both work, although the dome may be slightly better because there's little chance of it touching the leaves.


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RE: Diatomaceous earth for seed starting?

Evaporation cools the media holding the moisture, my greenhouse has been unusually dry due to the weather I had at the time I started the seeds in the DE, my greenhouse is is 100 Square feet with the peak at 12 ft. With nights dropping to -4 several times, temps never dropped below 52 at night but that was at 4 ft. above the floor. My seed trays were at 2Ft. from the floor with bottom heat, I should say a poor bottom heat source, that has since been upgraded to a commercial unit, I have noticed as much as 15 degrees difference with in 4 foot of elevation inside the greenhouse, so there are some variables that definitely come into play. Can you believe at 5 am this morning it was 18 in my back yard? and at 5 pm this evening it was 72? I have fans in the top of my greenhouse facing down as well as temp control exhaust fans, but with the extreme fluctuations I am sure the seeds were up and down during my trial with DE. Now that I am able to maintain an even temp I may try again at a little later date, at present I am using soiless Ball pro mix, it reminds me of my 511 with a considerable more amount of peat, I have had good results with this as a seed starter, and now with my new heat mat I should be good to go. I also have good results with this mix when I incorporate additional pine bark and DE, it functions much like 511, but does not maintain its integrity as long as 511. I just yesterday placed some cane begonias in a mix of 5-2 pine bark and DE, so maybe in a different thread I can report my findings later. Thanks for your tutoring guys!


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RE: Diatomaceous earth for seed starting?

I found the fallowing statement on another forum, I always disinfect my seed starting trays with bleach water, but don't always thoroughly rinse them with pure water, could this small amount of residual bleach water cause issues? Typically I use 1 part bleach to 10 parts water.

Do NOT use bleach or mix bleach with the water. Who started this rumour?
USING BLEACH WILL KILL YOUR seeds!!


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RE: Diatomaceous earth for seed starting?

I clean my trays with bleach. Never had a problem. I do rinse them!
OK, I got 5 out 6 starts in DE. Yesterday I put them in soil. I didn't see fantastic root growth, or really any advantage to using this medium as a seed start. I had to bare root the plants as the material just fell away when transplanting.
I thought all 6 were going, but when I looked again only 5 were btw. I thought I got 100%, I did not. Anyway I'm going back to a peat based mix for seed starts.
I like DE a lot though, you can grow seeds in it, I think it's going to make a great addition to my soils. So far excellent results as an amendment. My blueberries started growing right away. I got two plants in, and it's too early to put outside so potted them up. I'm growing them in pots anyway. But they are growing very well so far. Soil is staying moist but not wet, so far so good! I have confidence since the results from various studies show excellent results.


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RE: Diatomaceous earth for seed starting?

Final report: I think I have enough evidence to decide that I am never going to use DE to start seeds again.

Only 5 of the basil seeds I planted on Feb. 20 survived in the NAPA Floor Dry. Twice that many sprouted, but half of them died. They took about 10 days to germinate. After two weeks they hadn't even formed stems or true leaves, so I transplanted them to my standard seed starting mix about a week ago. They finally started showing noticeable growth and are doing well now.

On March 2, I started six different pepper varieties in two different mixes. Half of each variety was planted in my standard seedling mix (MetroMix 510, perlite and milled sphagnum moss) and half were placed on top of 100% DE and covered with a 50-50 mix of seed starting mix and DE. My reasoning for the second mix was that the surface of the straight DE dried out so fast, it was hurting the seedlings.

What you see in this photo are Giant Marconi seedlings on the left and Serrano seeds on the right. The top three cells in each case contain the DE. Two seeds were planted in each cell. As you can see, 5 of 6 marconis in the seed mix sprouted and look good. 4 of 6 marconis in DE sprouted, but they don't seem quite as healthy as the ones in straight seed mix. At lower right, 3 of 6 serranos sprouted and 2 look slightly better than the 2 of 6 Serrano seeds in the three cells at upper right.


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RE: Diatomaceous earth for seed starting?

Over at The TV forums people are having great success, and it worked for me too, I didn't really see an advantage though. But we are all using Ultrasorb, not NAPA floor dry. Although it should work too. Some people have been using it for years. Also with basil one guy reported excellent results. So I have no idea what went wrong? Looking at your seedling tray, it looks extremely overwatered. I never actually get algae growth ever in my trays. The five peppers I grew in DE are doing very well. But so are the other 30 I grew in seed starting medium. In a pinch i would use it again.


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RE: Diatomaceous earth for seed starting?

I reordered all the seeds that I attempted to germinate in DE, I started everything in pro mix March 14, today I potted 72 tomato seedlings that are 3" tall with roots that had filled the seed cell and was coming out the bottom, my failure or my very poor success with DE I have yet to figure what I done wrong, the only thing that I can think might have happened is fluctuation in temps, I upgraded my heat mat when I went with the pro mix, I had almost %99 percent germination with zero seed casings stuck. I will try again with the DE at a later date, it is very available for me and would love to see it work, but for now I have very good success with my current process.


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RE: Diatomaceous earth for seed starting?

I happen to be on that other forum as well, and have trialed the Ultrasorb DE quite a bit. I've compared pure Ultrasorb with commercial seed mixes. I have mixed it into other soils, but haven't compared that aspect in a systematic way.

Frankly, I've had incredible success. Tomato and pepper seeds come up at least a day faster when compared to off the shelf seed mixes (I've tried Jiffy, miracle gro, and a local brand) and overall germination is better, especially for marginal seeds. I have handling issues with tiny seeds and I've found it useful there. Watering is much easier. My least favorite part of seed starting is dealing with the hydrophobicity. You essentially don't have to worry about overwatering the DE.

More importantly, the seeds are really easy to remove when transplanting without doing much damage. No damping off, though I've rarely had problems with that anyway.

It has its own annoyances. It doesn't stay together even when wet, so you have to be careful about what kind of containers you use it in. The dust is a danger to be aware of.

Note I can only testify to the usefulness of Ultrasorb, by Moltan. There are differences to be aware of, though I also don't understand why that poster was so concerned with the pH of the medium. I don't know enough about it to discuss. I was more worried about the salinity.

Tiny seeds aside, I think Ultrasorb actually has the biggest advantage when it comes to very large seeds and things that normally don't transplant well. Acorns, walnuts, chinaberry, neem, are all things that did much better in the DE than either commercial seed starting mix or unsterilized 3:1:1. Hyacinth bean, castor bean, watermelon, squash, bitter melon, caesalpinia and moringa are other things I've had unusual success with. The lack of organic matter seems to minimize rotted seeds.

This post was edited by greentiger87 on Wed, Mar 26, 14 at 19:38


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RE: Diatomaceous earth for seed starting?

Greentiger: Thanks for your long detailed post. I am baffled about what happened with the NAPA product. I am growing a bunch of other seeds in my usual mix, and they are all doing well. I've never had problems with damping off or hydrophobicity, but I do have problems with the seed mix getting too compacted after a couple weeks if it is composed primarily of peat. I liked being able to bottom water the DE without worrying about getting it too wet.

But there must be something about the NAPA product that makes it different from the Ultrasorb. I don't think it's particle size or pH. I didn't mention that I also did a side by side comparison of growing Clivia seeds in it with my usual method of growing them in long fiber sphagnum moss. Clivia seeds are about the size of marbles and they are very slow growing, so they are prone to rotting in a mix that is too wet or drying out too much in a mix that doesn't retain enough water. I've always had good results in the long fiber sphagnum. I had four extras I popped into some NAPA about five weeks ago about the same time I put some in sphagnum moss. They had already sprouted tiny radicles. I just checked them, and the radicles on all four in the Floor Dry have rotted. The ones in sphagnum moss have grown tiny leaves and are doing well. So, now I've had bad luck with this stuff for basil, peppers and clivias. Something odd is going on. It makes me nervous since I use this stuff for the gritty mix I am using in at least 50 containers for house plants and perennials. I've been using it that way for over three years without apparent problems.


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RE: Diatomaceous earth for seed starting?

I have lately mixed some UltraSorb into my seed starting mix, )same amount as perlite. But I have not used it straight. (A bit too late as I am almost done with seeds starting
I think it is a good medium to root it it, as it holds moisture, it also has drainage. I may experiment adding like 15% to bark based soil, instead of peat. So this will be a sort of marriage between gritty and 5-1-1, the "1" in the middle becoming DE.


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