Diatomaceous Earth as a seed starting medium

[Greatgardens]

I've tried DE with fairly fine particle size from an auto parts store. (Think sizing similar to coarse sand.) Does OK, but I have one issue with it. Keeping it damp, the particles seem to "weld" themselves to each other after awhile. I don't get any better results than with Burpee's (coir) seed starting mix that is topped with about a 1/4" of vermiculite. Has anyone else noticed the DE particles sticking to each other?

[T0mat0stevek]

Has anyone started leeks in DE? If yes, what were your results?
Thanks, Steve

[RayR]

Originally Posted by T0mat0stevek

Has anyone started leeks in DE? If yes, what were your results?
Thanks, Steve

I've started onions and leeks in DE, it worked well.
The only seeds that may not perform as well are those that don't tolerate the naturally higher PH of the DE as well as the seedlings grows, but I haven't run into any that won't germinate in DE.
At the least I pre-sprout all larger seeds or those that can at least be handled by hand or tweezers (Tomato, Pepper, Eggplant, Lettuce, Brassicas etc..) on a bed of moist DE, much like you would use the paper towel method.

In the last number of years, I've learned to create my own seed starting mix of primarily the large granule Optisorb DE with Coco Coir and Worm Castings. That involves acidifying the DE with regular white vinegar, flushing it thoroughly with fresh water, then combining it with the organic ingredients and letting it sit and cook for a few days to stabilize the PH to around 6.50 more or less. Having a good PH meter is important for this so you can check the results. All my tomato seedlings will be raised this way until the potting up stage. I've already got lettuce and endive transplants ready to transplant now grown in the mix.

[T0mat0stevek]

This year I started my leeks, onions, and tomatoes in 100% DE with great success.

[paradajky]

Three questions for laughs:
1. Does calcined DE exist any more for the retail customer
2. Is it important to use calcined in this application given the short time seedlings are kept in it before up-potting
3. Why does it seem that seedlings have better performance in DE vs. something like Turface (or other calcined clays)

I went down the rabbit hole a couple years ago into the 1-1-1 gritty mix, and one option included subbing DE in the mix for turface and/or perlite. What I learned was the products listed 5-10 years ago have all changed, and it doesn't seem like we necessarily get the same things you all used to get then vs. now.

Here's some of what I learned. "100% natural" DE found in the automotive absorbent products was not calcined, and therefore, would breakdown into mush sooner. Calcined means baked at high temps (i.e. a kiln), which improves the longevity and absorption of the product.

Before EP minerals acquired Moltan, products such as Napa #8822, Floor-Dry, and ultrasorb were calcined. Unfortunately, it seems like all of them now are no longer as such. You can confirm this by looking at the packaging and SDS sheets for the various products - if it says "100% natural", or ingredients/SDS exclude "calcined" or use the word "natural", then this is the regular DE. Napa actually includes two SDS sheets, one is calcined, other is natural. I think that's to make up for any old stock left out there. Autozone uses the the old Moltan sds from 2007, which simply lists it as diatomaceous earth.

EP Minerals' description on their website lists Floor-Dry as being baked in a kiln, which complicates things but their other *sorb products are natural.

Somehow I suspect this isn't a problem for seedlings from a longevity standpoint, however, this may be why there are differences in pH and different levels of success people here have with the method.

I have a bunch of screened turface in my garage that I'd like to find a use for, and was considering using it to start next season's seedlings vs. purchasing yet another product to take up space in my garage like DE :p

Thanks for your time!

[DK2021]

Working my way through this very long thread and decided to jump to the end to ask if anyone has used this specific product: EP Minerals "Floor Dry"


https://www.grainger.com/product/EP-...sorbent-191W88


The tech sheet (link on above page) states that the pH is 6.5. I had seen a few earlier posts mentioning pH being too high but this is slightly acidic so I think (?) it could work for seed starting.


Any advise would be welcome. I usually just use commercial germinating medium for starting seed. Would love to try a DE medium if it reduces damping off/fungus but I also don't want to waste precious seed.



BTW Grainger lists 3 DE-based sorbents (not counting one that is "scented"):
https://www.grainger.com/category/sa...&filters=attrs

[KarenO]

I have never really understood the concept of planting seeds in this personally.

KarenO

[kurt]

https://buglord.com/how-to-use-diato...-to-kill-bugs/

[DK2021]

I've used DE as an insecticide but that is a totally different form--it's very fine powder, almost fluffy, and you use it as a dust.
The DE that I'm asking about is granular. I'm curious about trying it out as it may help with reducing damping off and/or algal growth.

[biscuitridge]

I use it for grafting medium, it works very well, but would never use it to start plants in.

[DK2021]

Originally Posted by biscuitridge

I use it for grafting medium, it works very well, but would never use it to start plants in.

Why not? I would like to try it out, but if there are real negatives to DE for germination I'd like to hear about them.

[T0mat0stevek]

In 836 posts almost all the negatives are from people who haven't tried it. For the past four years I have started all my tomato seeds in DE. All my onion seeds last year. All very successful.

[biscuitridge]

Originally Posted by DK2021

Why not? I would like to try it out, but if there are real negatives to DE for germination I'd like to hear about them.

It's more about seedling growth than germination, since there is no nutritional value in DE you have to supply everything that is needed for a healthy plant, also when you go to transplant them into the garden there can be issues with root disturbances. I find it works good for grafting because in the healing chamber it's very humid and you can have more problems with fungi,diseases etc.with soil but with DE you mitigate those issues to a great extent, I can usually get about 95 to 100% success using DE but not so with soil.

[biscuitridge]

And since I'm growing for world records I can't have anything to be detrimental at any phase of growth.

[DK2021]

Originally Posted by biscuitridge

It's more about seedling growth than germination, since there is no nutritional value in DE you have to supply everything that is needed for a healthy plant, also when you go to transplant them into the garden there can be issues with root disturbances. I find it works good for grafting because in the healing chamber it's very humid and you can have more problems with fungi,diseases etc.with soil but with DE you mitigate those issues to a great extent, I can usually get about 95 to 100% success using DE but not so with soil.

Yes I would plan to have to feed the seedlings of course, which I would do regardless of the medium composition.