Diatomaceous Earth as a seed starting medium
 

This experiment started in January when I was wondering how Diatomaceous Earth would work as a seed starting medium. I know that DE is used by some folks in hydroponics as a growing medium, it is also used by some folks in Bonsai, and studies have been done using DE as a soil amendment, but I’ve never ran across anyone who has used it as a seed starting medium. So my curiosity forced me to try it. I had some Blue Ribbon D.E. Premium Cat Litter manufactured by the Moltan Company which I have used as a potting soil amendment, so I had something to start with. From my research on DE I found that the PH of DE can vary depending on where it is mined, so I did a PH test with my digital PH meter and the Moltan product came in at a PH of 6.8 which was perfect, the same as a standard peat based seed starting mix. My first experiment was with Llia Onion seed and the results were very impressive, I grew some very healthy onion seedlings with no problem.
My second experiment came in mid-March with tomato seeds. I found that Moltan makes the same DE product sold as an oil absorbent called UltraSorb which I found right down the street at the local AutoZone in a 15lb bag for $5.99. The only difference between UltraSorb and the kitty litter was the granule size, the UltraSorb is a much less coarse granulation (more like coarse sand), which was easier to work with.

I seeded 24 Brandywine and 24 Black Krim, half in Jiffy Seed Starting Mix and half in DE.They were bottom watered with distilled water, put on the heat mat under lights and given no nutrients until they developed their first true leaves. The germination rate was exactly the same. Here is what they looked like today. See any difference?

I love experiments. Nice job. Thanks.

That is just wild! I love it!

I'll let these go a little longer before potting up, but I'm seeing little difference in growth other that the noticeable bigger leaves on a number of the Brandywine seedlings on the DE side.

I've got some DE experiments with peppers and basil in the works too, so we'll see what develops there.

Ray, does it wick up like peat, if watered from the bottom?

It wicks up much faster than peat, it also retains the water very well over time.
It also has a respectable cation exchange capacity, so it holds nutrients in the medium.

Ray, thanks for posting. I think we need a whole sub-forum for experiments!

Steve

^+1!

Thanks so much for this. I love that you though of this, tried it, and posted!

I think I'll try this with the seeds I got from Carolyn. I have 1 each left, and I already know that they don't like my other potting medium. Out of 5 varieties and 27 seeds sown, only 2 emerged after 12 days. I haven't given up hope, but I'd love to see if I get germination on those singles.

Janezee, it can't hurt to change your seed starting medium when you have some troublesome seeds. Although I haven't had much trouble with tomato germination this year, I have had some issues with certain pepper varieties. In my first sowing of peppers, with Chinese Giant bell peppers I got zero germination with 9 seeds sown in Jiffy mix. In my second sowing I planted 12 seeds in Jiffy mix and 12 seeds in DE. I got 5 strong seedlings pronto in DE and 2 in Jiffy mix. Go figure.

Sounds good, Ray. It can't hurt at this point.

Pepper Experiment
 

This is my first experiment with Pepper seeds in Diatomaceous Earth. I seeded 18 Chinese Giant Bell and 18 Hungarian Hot Wax, half in DE and half in Jiffy Mix.
My stubborn Chinese Giant seed did pretty well in the DE with 5 strong seedlings, but only 2 in the Jiffy Mix, the germination for the Hungarian Hot Wax turned out equal with 7 seedlings in each medium.
What is more important is the rate of growth, both varieties of peppers are growing much faster in the DE, Any ideas why?

Could DE be used as a portion of a potting soil mix? If so, which porting and what percentage? Not for earth boxes.

[QUOTE=Tracydr;271347]Could DE be used as a portion of a potting soil mix? If so, which porting and what percentage? Not for earth boxes.[/QUOTE]

Absolutely, I know some folks here on TV have used it to amend their container mixes as have I. I'm even trying it as an amendment to my garden beds this spring.
It can be used alone or in combination with perlite. It's very light in weight, but not quite as light as Perlite. Both are composed of mostly silica, Perlite is manufactured by expanding hydrated volcanic obsidian glass, DE is a natural deposit, the fossilized silica skeletons of prehistoric diatoms. Both are made of mostly stable and inert amorphous silica, but DE contains a small amount of soluble silica which can be utilized by plants.

How much to use? I don't know exactly, that would take some experimentation itself.

There is a commercially made high end potting mix that is made locally here in Western NY called [URL="http://www.ncwgs.com/just_right_xtra.php"]Just Right Xtra All Organic Potting Mix[/URL] which doesn't use any Perlite at all in the mix, but they use a very coarse horticultural grade DE that is also the same type that is used as a medium in hydroponics.

The Tomato plants were starting to look unhappy in those small cells, so a few days ago I started potting them up. As you can see from the pictures, the roots of the tomato seedlings grown in the DE were long, thicker and fibrous. It was a lot easier to separate the seedlings in the DE than in the Jiffy Mix. It took a lot of massaging of the Jiffy Mix roots to minimize damage so I could get a fair comparison.
I think next time I do this, bigger cells would work better. I didn't expect the roots of the plants in the DE to get this huge. Anyway they are all looking much happier now that they are separated and potted up with lots of room to stretch.

As an aside, we have a small section of our backyard tomato garden which borders our fairly large pool filter/heater. Every six months or so (when cleaning the filter itself) we fold in some of the used DE - along w/ all the organic nutrients included in the mix and have found it truly beneficial to the plants.

They seem to do considerably better than the section which hasn't received the mix and the neighbors garden who doesn't have a pool.

Will in So. Cal.

Several years ago, I used diatomaceous earth product as a portion of starter mix, along with peat making up the majority of the remainder. The DE was an oil absorb product I bought at Rural King in a large bag, I believe was about 50 lbs., and much cheaper than what Ray indicates today's price may be. But then there's the immense increase in mining, drying, processing and shipping costs over the past few years to consider. The material was baked, and was much whiter than what Ray shows in his pictures.

The only problem I had was algae growing on the DE, but Ray's photos don't seem to show the same problem.

I think I'll try DE again next year, but go 100% DE as Ray did, water solely from the bottom, and see how it works for me. I'd really like to use something besides peat, vermiculite, perlite, and coir, all of which have posed various problems for me either with regard to cost, function, or sustainability.

The color of DE does vary, it's not always pure white. There are impurities that will account for the color—minerals and volcanic clay particles. The UltraSorb is much whiter when it is dry, but when you add water the earthen tones really come out. The UltraSorb is baked too at about 600°F from what I've read, to dry and sterilize it, but that doesn't alter the color, and it doesn't alter the amorphous structure of the silica. Calcined DE like what is used for pool filers is heated to a much higher temperature near the melting point which changes the structure of the DE and creates a lot of unhealthy crystalline silica. Never us that stuff.
My main concern was choosing a natural amorphous fresh water DE that had the proper PH for a seed starting medium.

Travis, I have had algae growth on the surface of the DE, but only when I used rain water. It didn't occur when using distilled water. It didn't show up much with the Tomato's though. Luckily the algae is harmless. Fungus won't grow on DE since fungus needs dead plant matter to grow on, which is probably another advantage of the DE—no chance of damping off.

This is all very interesting.

First of all, originally I was only familiar with diatomaceous earth (DE) as a water filtering medium.

Secondly, I was under the impression that all DE was calcareous, fossilized, single cell skeletons of some ancient diatoms (hard shelled algae thingies).

I did not know they are siliceous. I was worried that using too much DE would raise the pH of my mix. So, I should be looking for what in particular info on the package to indicate pH below the 7.0 neutral point?

DE is not calcareous at all, at least not the [URL="http://www.moltan.com/msds/MSDS%20pdf/MSDS_DE_UltraSorb.pdf"]UltraSorb[/URL], there may be trace amounts of calcium Carbonate in there but [URL="http://en.wikipedia.org/wiki/Diatom"]Diatoms[/URL] make their shell out of silicon dioxide. I think the closer you get to a pure DE deposit, the closer to a neutral PH you will get. I don't think you are going to find the PH specified on bags of DE sold as absorbent products, I only verified the PH of the UltraSorb by testing it with my PH meter.
You could use a horticultural grade DE which naturally would require it to be around a neutral PH, but at least around this area you are only going to find it sold at a hydro store in a granule size about like Perlite.

I'll just get the auto oil absorb product and go for it! Thanks for the info, Ray.

Time to pot up the peppers
 

One week has gone by since my last post on the pepper experiment and tonight was the night to take a closer look and pot them up. All the seedling are healthy and have grown some, the seedlings grown in the DE still outpaced the seedlings in the Jiffy Mix. Besides being a bit taller, the leaves were noticeably larger and the stems thicker and like the tomatoes, the root mass was larger and more fibrous.
I'm still thinking the next time I do this I will start the seeds in 2" or 3" cells instead of the 1.5" cells I used this time. More space with less root competition could yield even better results.:yes:

Would "Fuller's Earth" also work? It's similar, and also marketed as a cat litter product (7 lbs for $1 at the local, um, dollar store) but haven't done enough research to determine whether it might also be suitable for plants. The Moltan products, even at AutoZone, do at least mention planting on the label....

Way to go, Ray! Thanks for the update. I will try this out for sure!

j

[QUOTE=rsrb;274717]Would "Fuller's Earth" also work? It's similar, and also marketed as a cat litter product (7 lbs for $1 at the local, um, dollar store) but haven't done enough research to determine whether it might also be suitable for plants. The Moltan products, even at AutoZone, do at least mention planting on the label....[/QUOTE]

"Fuller's Earth" is a name that is used broadly to include many forms of weathered volcanic clay. You could have 2 different products claiming to be made from "Fuller's Earth" and both can have totally different properties and mineral composition.
If you could find a clay that had similar properties to DE (soft rock-like structure, stable in water and a near neutral PH), then it might work, but I haven't found one like that yet. They all tend to be lower in PH, 6.0 and under.
For instance, Moltan's other cat litter and oil absorbent products that are not DE is made from Montmorillonite Clay that is from their mine in Tennessee. I got some of cat litter version, it is a hard non-swelling clay, stable in water and absorbent but it tested to be a PH, of 4.8.:no: Just for fun I tried a side by side comparison growing onion seeds in it and DE. I was actually surprised that the onion seedlings germinated and grew in such an adverse PH situation, but they didn't do very well compared to the onions in the DE. (See picture, this was at 30 days from seeding)

My husband stopped at Autozone the other day. I was waiting in the car and saw the oil sorb in the front window on sale, nice big bag. I almost went in and bought a bag, since I'm out of seed starting media, except for my Jiffy pots.
I may go back and get some for my fall starts, it's getting close to time to think about things like celery, artichokes and maybe Brussels.

[QUOTE=Tracydr;274871]My husband stopped at Autozone the other day. I was waiting in the car and saw the oil sorb in the front window on sale, nice big bag. I almost went in and bought a bag, since I'm out of seed starting media, except for my Jiffy pots.
I may go back and get some for my fall starts, it's getting close to time to think about things like celery, artichokes and maybe Brussels.[/QUOTE]

The UltraSorb is the DE product, AutoZone sells it in a 15lb bag. AutoZone also sells the Moltan clay absorbents in 8lb and 33lb bags, you don't want those.

It's interesting to see what seedlings work best in DE, I suspect some will do better than others, although my experiments with onions, tomatoes and peppers turned out well, my basil is not working out well in the DE for some reason.

Here are 2 examples of my experiments on germinating seeds in diatomite.
First photo [I]Ocimum gratissimum[/I] 2.4.2011
Second photo[I] Ocimum gratissimum[/I] 26.5.2011
Third photo [I]Solanum abutiloides[/I] 15.4.2012

Looks good Levent. Did you notice any difference in growth with the Basil in DE and in whatever seed starting mix you normally use?
What do you do with the Dwarf Tamarillo anyway?

Hi Ray,
I noticed the difference ten years ago!Since then as germinating medium I have used only diatomite.I grow mainly house plants (Stapeliad and Hoyas) in diatomite using simple hydroponic techniques and also some edibles for fun and consumption.[I]S. abutiloides[/I] is a novelty for me this year.I plan to consume ripe pods (they're edible) I transferred two plantlets to garden, one to pot culture (ıt's under a porch facing south) one to subirrigation pot (it's in greenhouse) all the rest were donated to relatives.The one in pot culture heads for now and has buds on apical shoot.

I have only been involved with DE for getting rid of the fleas that my collies picked after we moved here, and of course keeping the ants out of my house up north. I love when a product has multiple uses.

Thanks so much for sharing your results. I'm gearing up to for seeds next month and I think I'll try some seeds in it.