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ohiofem

Diatomaceous earth for seed starting?

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.

Comments (90)

  • stimey
    10 years ago

    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?

  • greenman28 NorCal 7b/8a
    10 years ago

    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

  • stimey
    10 years ago

    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.

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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?

  • greenman28 NorCal 7b/8a
    10 years ago

    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

  • stimey
    10 years ago

    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

  • drew51 SE MI Z5b/6a
    10 years ago

    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%20for%20POTTING%20SOIL.pdf

  • tapla (mid-Michigan, USDA z5b-6a)
    10 years ago

    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

  • drew51 SE MI Z5b/6a
    10 years ago

    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

  • stimey
    10 years ago

    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

  • seysonn
    10 years ago

    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

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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

  • seysonn
    10 years ago

    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.

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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

  • seysonn
    10 years ago

    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).

  • tapla (mid-Michigan, USDA z5b-6a)
    10 years ago

    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

  • drew51 SE MI Z5b/6a
    10 years ago

    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

  • drew51 SE MI Z5b/6a
    10 years ago

    Another photo looking at roots.

  • drew51 SE MI Z5b/6a
    10 years ago

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

  • stimey
    10 years ago
  • seysonn
    10 years ago

    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.

  • drew51 SE MI Z5b/6a
    10 years ago

    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!

  • Beach_bums
    10 years ago

    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.

  • tapla (mid-Michigan, USDA z5b-6a)
    10 years ago

    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

  • seysonn
    10 years ago

    So let's get back to talking about seeds!

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

  • stimey
    10 years ago

    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?

  • greenman28 NorCal 7b/8a
    10 years ago

    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

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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:
    {{gwi:4991}}

    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:
    {{gwi:4992}}

    Thoughts?

  • drew51 SE MI Z5b/6a
    10 years ago

    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.

  • seysonn
    10 years ago

    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

  • stimey
    10 years ago

    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.

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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.

  • seysonn
    10 years ago

    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.

  • drew51 SE MI Z5b/6a
    10 years ago

    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.

  • greenman28 NorCal 7b/8a
    10 years ago

    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

  • tapla (mid-Michigan, USDA z5b-6a)
    10 years ago

    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

  • maple_grove_gw
    10 years ago

    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

  • drew51 SE MI Z5b/6a
    10 years ago

    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

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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.

  • stimey
    10 years ago

    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?

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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.

  • stimey
    10 years ago

    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!

  • stimey
    10 years ago

    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!!

  • drew51 SE MI Z5b/6a
    10 years ago

    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.

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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.

  • drew51 SE MI Z5b/6a
    10 years ago

    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.

  • stimey
    10 years ago

    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.

  • greentiger87
    10 years ago

    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

  • Ohiofem 6a/5b Southwest Ohio
    Original Author
    10 years ago

    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.

  • seysonn
    10 years ago

    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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