I've used diatomaceous earth as a non-toxic insecticide but have never heard of it being used as an oil-dry product. For those who don't know, it's like razor blades to insects. It cuts the exoskeleton, which leads to dehydration. To you and me, it just feels like flour.

I googled it and indeed it's being marketed by Moltan, Sullivan, and others as an adsorbent. I'm sorry that I can't lend any insight to long term stability in a potting mix. You might pick up a small bag, test it out, and let us know how it works. I'd be interested to see how it performs.

I think as long as the product does not have additives and is salt free, it would be a decent replacement for the grit in a medium. Certain cat litters, oil dry products, and diatomaceous earth can all be used as long as they meet certain criteria. I've been searching for different products, myself, as I doubt I'll find everything exactly as listed in Al's recipe.

Here's a great link to some bonsai basic information... they discuss the use of litters and oil dry products, as well as diatomaceous earth... read on...

Here is a link that might be useful: Bonsai Basics - Soil

I use Napa's oil absorbent (part# 8822). Many bonsai growers have been using it successfully and I really like it as well. It's a lot like Turface (same size and shape), but a bit lighter due to its higher porosity. Also, it's gray to white in color as opposed to the tan color of Turface. I haven't seen any decomposition in the several months I've been using it, but I don't expect to since I've never heard of it occurring for anyone else. I think I payed $7.50 for a 25# bag (6 gallons). I currently use a mix of equal parts pine bark, Turface, and DE which seems to work very well.

The calcined DE products are actually going to be better than Turface in a couple of areas. They have greater porosity, so they hold more water, and have a better CEC, which isn't as important in containers as it is in the garden, but it's still a plus.

Remember though, that size is a consideration. The oil-dri products won't be larger than Turface, but it's possible they would have a high % of dust and fines. Screening (through aluminum insect screen) might be appropriate if you're using them in something like the gritty mix.

Al

Well after reading some posts plus Al's comments it looks like the calcined DE products would be a good substitute for those members who cannot locate Turface locally.

I've not tried this but out of curiosity I might buy a bag and see what happens.

Most auto parts stores should have this, but be sure to read the ingredient list ont he bag and make certain that it contains "diatomaceous earth".

Thanks.

Dave

From what I understand, NAPA Auto Parts sells their own brand of oil dry, and this is what many people use.

My problem is finding the pine bark in small enough particle size... and suggestions?

JodiK,

Yes the oil absorbant I saw was also at NAPA auto parts, but other auto part stores probably have something similar. If you are considering this for use in Al's mix be sure to read the label and make certain that it contains DE. If it doesn't, I'd stay clear of it.

As for the pine bark, up until last year I bought mine in 3CFT bags at a local Meijers store (large upper midwest regional chain). They had a brand called "Royal Gardens" (I think) and their pine bark mini nuggets were very close to what Al recommended for the gritty soil mix. Last year Meijers changed brands and carried only the big decorative pine bark mulch, far too large for the soil mix.

I eventually found some small pine bark nuggets at a small local garden and landscaping center. They bagged their own mulch and had the small mini nuggets for about $4.00 per bag.

The only advice I can suggest is to look at the big box stores early this spring, once their garden shipments start to come in. If they don't have anything small enough then maybe try and find a small local landscape supply center and hopefully they will have it.

Hope that helps

Dave

I think I may have found something that will work, at Lowe's... we have a Meijer's in the area, so I'll check there, as well. It's still early for the spring shipments of gardening supplies to hit the shelves, but I'll keep my eyes open.

We have all the usual big box stores in town, so I'm bound to find something that can be used. If not, I should be able to order something satisfactory. Thanks for the information!

I use a cat litter sold at the dollar stores. It's called Blue Ribbon I believe, and it's all 100% DE. The bag recommends using it in the garden, to clean oil, for litter pans and for many other uses. It's supposed to help retain moisture. I have a planter that no matter how much I watered it, it would dry out right away, and ever since I added the DE Litter, it doesn't dry out as fast, and I was able to grow basil in that planter, and even green onions.

I was never able to find Turface in my area, so I started using DE (from an auto-parts store) in my own version of Tapla's soil mix a couple of years ago. I mix equal(-ish) parts bark, DE, and peat moss. Tapla's more complicated mix is probably far superior, but I'm much lazier than he is. :-p

I use this mix in all my containers, and it works really well for me. I even got a half-dozen kinds of seeds to start outside in it this year (this was a big achievement for me). I don't sift the DE, I just dump it in with the rest and stir, and water my plants with diluted hydroponic fluid sometimes (when I think of it).

I'm sure some of the more experienced gardeners are cringing at all of the things I'm doing wrong, but somehow my plants thrive. :-)

I used to use DE as a insect barrier years ago until someone informed me that it is extremely dangerous to breath (think of thousands of tiny razor blades in your lungs). Just a word of caution. If this is an "urban legend" please let me know so I can start using it again!
Nik

You should always use a good measure of caution whenever working with a material that will produce particles that can be inhaled. I don't think I would be all that concerned about carefully spreading a tablespoon or two of the fine DE as remedial for insects, but I do use a paper mask when I'm screening the materials for my soils. It only takes a second to slip one on, and they're very inexpensive.

Al

I recently found a supplier of "horticultural grade" diatomaceous earth, recommended by a bonsai-growing friend.

It's apparently excellent stuff: the texture and drainage of gravel, however it retains some moisture which, I believe, is due to its high porosity.

I'm thinking of using pure DE as a container medium - and be prepared to water and feed regularly (with a soluble general purpose fertiliser). Has anyone tried this? Is there any real need to incorporate pine bark, apart from economic reasons?

Thousands of people do it with similar mediums (hydroponics), which is essentially what you'll be doing, so there's no reason it can't work very well.

You'll need to be very careful about your fertilizing, making sure you have a full compliment of nutrients. Foliage-Pro 9-3-6 should be an excellent choice. Because the pH of DE is around 7.0, you'll probably find you will need to acidify your irrigation water to get the best results. I would use pH paper to see how much vinegar or citric acid it takes to lower a given volume of your tap water to a pH of about 6.0, and add that amount of either to the water before irrigating.

Al

Please note: I suspect that NAPA auto sells two types of oil absorbent.One is called oil dri in 40 pound bags.That is the tipoff.it is soft clay pellets.the good stuff is called Superabsorbent in 25 lb,bags.Superabsorbent is the diatomaceous material that you want.GUESS WHO BOUGHT 120 LBS.OF THE WRONG STUFF!!!The item # is 8822 at NAPA for Superabsorbent.
live and learn even at 83.

Napa will usually take exchanges without a problem if you buy the wrong item, at least for parts.

I-called my local store this a.m.and they will have a hundred lbs.(4 bags ),of SUPERABSORBANT # xxx 8822 for me from the ware house tomorrow. go to the NAPA.com web site and search under "oil" to see if your store keeps it in stock.an old fashion way to find out is call them and ask.NOTE the exact item #xxx 882 OLD DOC.

I've been using the Napa 8822 for the past few years in the gritty mix and it has worked beautifully. I've purchased approx. 20 bags of the stuff and all have been solid performers with relatively few fines. I've purchased 3 bags (50#) of Turface and all 3 had a much larger percentage of fines than the Napa. They may be different depending on batches, but it has been consistent for me. Take a look at who generates the Napa product -- it's written on the bag down at the bottom: EP Minerals. Same folks, nearly identical product, as Axis (Turface competitor).

I did a breakdown the first time I sifted and Turface had approx 20% waste whereas the 8822 had only about 2%. So although the 8822 was like 2 bucks more for 50lbs, it was still less expensive.

Yes inhaling small particulates into the lungs is never a good thing. I think the concern is called airborne silicosis caused from the tiny silica that is generated from the firing process. There *might be* more silica in the calcined DE (Napa), but there is definitely dangerous amounts of it in calcined clay (Turface) as well. You really should b wearing the NIOSH n95 mask either way.

Hello All,
I just joined the forum, and enjoyed reading the Al's posts on Container Soils, Water Movement in Containers, etc. Doing some online research, I discovered that the Napa #8022 is manufactured by Moltan Corp, from the MSDS sheet on the product. I purchased the Moltan products #8804 and #8834 from my local Auto Zone store. Both are Calcined DE products and have held up soaking in water (3 weeks so far). I found another benefit with Calined DE is
due to its larger porosity diameters, it holds more plant
usable water (PAW) to tensions of -1500Kpa. Calcined DE has
approx 33.8% PAW compared to Calcined Clay 17.6%.

Hello All, correction to previous post:
I discovered that the Napa #8822 is manufactured by Moltan Corp, from the product Material Safety Data Sheet on the NAPA Website.

Interesting, Dale. Is there a difference between the two products? What are the particle sizes?

Hello,
As far as particle sizes, I screened a cupful of #8834 through a set of Bonsai Screens. the range was from 3mm to 1mm. Just a few granules were left on the 3mm screen, about
equal amounts on the 2mm an 1mm screens. Just about 1 to 5%
went trough the 1mm screen. On the Moltan Website they list
#8834 as coarse granulation, and #8804 as Medium granulation. Visually the #8804 looks a little coarser to me. The #8804 was a 5lb bag, I purchased for testing purposes. window srceen is about 1/16 in mesh, which is approx 1mm with wire diameter included. I contacted Moltan
via Email to inquire about granulation sizes, calcining temps, comparison on Napa#8822 to other Moltan products.
I will post the response when recieved.

I realize I'm late to the party, but thought I'd ask. :)

I found Oil-dry at Wal-mart and was pretty happy about it. The ingredients are listed as "Natural Earth Products." Huh?

Dare I assume it would be ok in the gritty mix?
Thanks for your opinion.

I wouldn't assume anything, especially if you don't really know what it's made of. You could test it by letting a bunch of it soak in water for a few days, and then see if it disintegrates or not.

If the size of the product in question is appropriate and has no perfumes or phytotoxic additives, I would add a half cup or so to a plastic cup, cover it with water, pop it in the freezer overnight, and ck it for structural stability after it thaws.

Al

I'll pick some up when I get back from MI.