Diatomaceous Earth as a seed starting medium

[MrsJustice]

Originally Posted by RayR

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.

Going back and reading this forum from the beginning, it is good to learn that DE can be used by people that enjoy DE. Yes, it can be used for people's survival methods if we were in a war or a natural disaster. I still would not trade in my Miracle-Gro Planting Soil. I am trying Pitt-Mott for the first time this year on Shepard Mallory Muscadine GrapeVine requested by a Local Pastor following his Growing Methods he wants me to use.
But I still want my Miracle-Gro, Amen!!. I guess it's easy to use for Female Farmers like me, and a Safe product for the Native Americans who mix this product with their own yard dirt.

[MeWhee]

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.

[travis]

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.

[RayR]

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.

[travis]

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?

[RayR]

DE is not calcareous at all, at least not the UltraSorb, there may be trace amounts of calcium Carbonate in there but Diatoms 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.

[travis]

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

[RayR]

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.

[rsrb]

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....

[RayR]

Originally Posted by rsrb

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....

"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. 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)

[Mark0820]

Originally Posted by RayR

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)

Ray, thanks for starting this thread. I never would have thought of using DE for starting seeds. The pictures of the root growth on the seedlings are impressive. I've enjoyed reading and learning from this thread. I think I will try this method in 2015.

I don't want to get off topic, but I saw your onion seedlings, and wondered if you could give me a few tips on growing onions. I have never had much success growing them. All I ever get are a few small onions. Would you mind using one post to give me a few tips for growing large onions?

[RayR]

Originally Posted by Mark0820

Ray, thanks for starting this thread. I never would have thought of using DE for starting seeds. The pictures of the root growth on the seedlings are impressive. I've enjoyed reading and learning from this thread. I think I will try this method in 2015.

I don't want to get off topic, but I saw your onion seedlings, and wondered if you could give me a few tips on growing onions. I have never had much success growing them. All I ever get are a few small onions. Would you mind using one post to give me a few tips for growing large onions?

For onions make sure you are growing a variety that is suited for your area. Since you are in the North, only grow long day or day neutral varieties. Short day varieties for the South won't make large bulbs up North. If you are growing from seed, start them early, they grow much slower as seedling indoors under lights. I typically start as early as the beginning of January. Consistent moisture and fertilize them well. Don't crowd the seedlings, separate the strongest seedlings into separate cells for faster growth. Plant out in early spring when you can work the soil and fertilize, onions are hungry plants. Plant in a area that get lots of direct sunlight, that's critical. Watch the weeds, onions don't like the competition. That's pretty much it, they'll grow pretty fast when in the ground outdoors and you should get some good size bulbs in summer.

[janezee]

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

j

[Tracydr]

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.

[RayR]

Originally Posted by Tracydr

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.

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.