Diatomaceous Earth as a seed starting medium

[tnkrer]

Planning to use DE as seed starting medium this year. A few questions.

1. I usually let the seeds sprout in a wet paper towel in plastic bag before putting them in starters. Would that be unnecessary? or problematic with DE?
2. I understand that we need to bottom water, however, Do I need to wet the DE in the cells at the beginning? Or is that also done by wicking bottom water? If I wet the DE in the cells when I put seeds in there, How much water to use?
3. What should be the planting depth for the seeds?
4. After the seedlings emerge, I plan to add fert to the water tray. miracle-gro liquid fert - they say 1 teaspoon per gallon for plants. what should be the ratio for this use?

Thanks
(I am still reading the long thread and if/when I find answers, I will answer my own questions in the post, but if you know the answers, please let me know. I am sure that fert question has been answered before. )

ETA: #1 Asked and answered in posts 255 and 256. pre-sprouting should not cause any problems
#2 asked and sorta answered in 285, 286 and 287
#4 discussed in posts 300 and 301, but not answered there

[dipchip2000]

Tnkrer

My experience only and just tomatoes. Peppers have not sprouted yet.

#1 pre sprouting totally unnecessary

#2 I bottom water the DE till it wicks up water and changes from white to wet grey. After planting seeds I mist each cell to smooth it out from seed planting

#3 I planted about the depth of a pencil eraser

#4 I used and am still using 1/4 teaspoon per gallon till potting up when I switch to one teaspoon per gallon

I am far from an expert but my plants look very good now

we will see

ron

[RayR]

1.) Forget the paper, save a tree, pre-sprout your seeds in DE. Hmm..sort of poetic, ain't it? Posts 508 and 545

I usually don't pre-sprout tomato seed unless I think they may be iffy because they are old or untested saved seed. Pepper seed, I will always pre-sprout from now on.
I pre-sprouted onion seed last month, that worked well.
I pre-sprouted some lettuce seeds on DE last week, some from saved seed in 2010, got great germination on those. Some from a seed packet bought in 2010, got low germination, but still got 6 good ones out of 25 seeds.

2.) Yes, pre-wet the DE like Ron said

3.) I plant most tomato & pepper seed at 1/8" - 1/4" Ya, around pencil eraser depth.

4.) I haven't used synthetic ferts with DE, but 1/4 strength seems safe enough for seedlings with any medium.

[peebee]

I happened upon this post recently and bought DE last weekend. It's fabulous! I tried a side by side test on basil, one pot in Pro-Mix, one in DE, on a heating pad. The DE seedlings came up a day earlier. I also did the same basil seeds in DE w/out a heating pad, and it came up on the same day as the Pro-mix(so a day later than DE w/ heat pad).
Have one question and I tried to read thru as many posts as possible, but with over 600 postings it will be a long time till I find my answer, so I will ask:
What are some of your methods of potting DE so that the fine grains do not spill out the drainage holes? I use small pots inserted in small baggies so that I can bottom water and move the pots around. But I am not satisfied with this method. I know screens will likely work, I'll just have to hunt down my screens and begin cutting them to fit again. Any better ideas?
Thanks!

[tnkrer]

Ron, Ray - Thank you very much!
I need to find bunch of small lidded containers now to sprout the seeds. That is not a very scalable solution though. I will need as many containers as many varieties I am planting!
question about how much water to use and how often to rewet the sprouting layer .. It was not very clear from the pictures in the post. Do you water to thoroughly wet the DE? and then not water it again at all? (The lid would make sure that nothing evaporates)

[RayR]

Originally Posted by tnkrer

Ron, Ray - Thank you very much!
I need to find bunch of small lidded containers now to sprout the seeds. That is not a very scalable solution though. I will need as many containers as many varieties I am planting!
question about how much water to use and how often to rewet the sprouting layer .. It was not very clear from the pictures in the post. Do you water to thoroughly wet the DE? and then not water it again at all? (The lid would make sure that nothing evaporates)

Just saturate the DE layer, if it's a little more than saturated that's fine since the seeds will absorb a bit of water themselves. With it covered most of the time your're not going to lose much moisture just like the paper towel/coffee filter method in a plastic bag. I usually don't have to add any additional water before they sprout, but if looks like it needs a little additional moisture just give it a squirt with a spray bottle.

[Father'sDaughter]

Originally Posted by peebee

What are some of your methods of potting DE so that the fine grains do not spill out the drainage holes? I use small pots inserted in small baggies so that I can bottom water and move the pots around. But I am not satisfied with this method. I know screens will likely work, I'll just have to hunt down my screens and begin cutting them to fit again. Any better ideas?
Thanks!

While there are several solutions, I personally use coffee filters. I cut them into squares then dip them in water and press them into the bottom of the pots before filling them with DE.

[peebee]

Father's Daughter, that is a GREAT idea! I never would've thought of coffee filters, and since I have those Aeropress ones, they are the perfect size and round, so voila--no cutting necessary! Thank you!!!

[Virtex]

Paper towels work great as well.

[JamesL]

I am jumping on the DE train this year, primarily to experiment with some of Delerium's grafting methods. Picked up some Ultrasorb from Autozone this morning. I believe I am going to pick up some Optisorb as well and use it to pot up after grafting until plant out.
I am going to pre-germinate my seed and as usual and then drop them in an egg carton setup once the radicles emerge.
I usually pre-germinate and them move into potting blocks with a seed starting mix and upon potting up hit them with a 1/4 strength dose of SeaStart (-0-4-4).

Question - Any thoughts on "pre-charging" the egg carton DE with a very weak dose of the SeaStart?
Is this a bad idea in general, or if it is an OK idea, should I be using something with N in it instead?
I was thinking a pre-charge of 1/8 to 1/10 strength and then waiting a week before adding any more fertilizer.
Thoughts?

[RayR]

Originally Posted by JamesL

Question - Any thoughts on "pre-charging" the egg carton DE with a very weak dose of the SeaStart?
Is this a bad idea in general, or if it is an OK idea, should I be using something with N in it instead?
I was thinking a pre-charge of 1/8 to 1/10 strength and then waiting a week before adding any more fertilizer.
Thoughts?

It's not a bad idea to pre-charge with a light dose of liquid kelp like SeaStart, the hormones in it may encourage root development.

Technically the seedling can't utilize nutrient cations until it has developed an actual root system which is about the same time true leaves appear, until then it is feeding off the stored nutrients from the seed. I have been pre-charging the DE though with a liquid organic fertilizer at half strength and a biological inoculant from the beginning with no problems. The way I look at it is, DE is like any other good soil-less medium, it has good cation exchange capacity but it doesn’t naturally contain many nutrient cations. When you add a liquid organic fertilizer, some available cations will populate the cation exchange points in the DE and the rest of the organic nutrients will be sequestered by the bacteria and fungi as food to get their life cycles going and producing beneficial metabolites that are going to help the seedling. The seedling will grab what it needs when it’s ready.

With synthetic fertilizers it’s a different story, either pre-charge with an extremely light dose or just wait until true leaves to appear to lightly fertilize.

[b54red]

Originally Posted by peebee

I happened upon this post recently and bought DE last weekend. It's fabulous! I tried a side by side test on basil, one pot in Pro-Mix, one in DE, on a heating pad. The DE seedlings came up a day earlier. I also did the same basil seeds in DE w/out a heating pad, and it came up on the same day as the Pro-mix(so a day later than DE w/ heat pad).
Have one question and I tried to read thru as many posts as possible, but with over 600 postings it will be a long time till I find my answer, so I will ask:
What are some of your methods of potting DE so that the fine grains do not spill out the drainage holes? I use small pots inserted in small baggies so that I can bottom water and move the pots around. But I am not satisfied with this method. I know screens will likely work, I'll just have to hunt down my screens and begin cutting them to fit again. Any better ideas?
Thanks!

If your drainage holes are not too large then you can use some of the Optisorb which is just a much larger form of diatomaceous earth on the bottom of the pot. I just use egg cartons and use smaller holes and tape up the lids with duck tape to use as watering trays. I write the variety on the flap. If I am doing more than a couple of varieties in one egg carton then I fold a piece of duck tape over the flap from one end to the other to give me a better writing surface.

I never do any pre-sprouting of any type of seeds nor do I cover the DE with anything. I just make sure it stays moist until they germinate then start watering with a mild fertilizer solution then pot up into larger cups filled with potting soil when they are big enough to handle. I don't pot up lettuce because it will do fine in just the small egg cell filled with DE. I leave onions in the DE until I plant them but I use a fairly large pot at least 5 or 6 inches deep filled with DE.

Bill

[tnkrer]

Originally Posted by tnkrer

Ron, Ray - Thank you very much!
I need to find bunch of small lidded containers now to sprout the seeds. That is not a very scalable solution though.

Found a scalable solution. 50 cups for $2.19 at Walmart

Those should work fine for sprouting .. right?

[RayR]

Originally Posted by tnkrer

Found a scalable solution. 50 cups for $2.19 at Walmart

Those should work fine for sprouting .. right?

Good idea, those should work great.

[JamesL]

Originally Posted by RayR

It's not a bad idea to pre-charge with a light dose of liquid kelp like SeaStart, the hormones in it may encourage root development.

Technically the seedling can't utilize nutrient cations until it has developed an actual root system which is about the same time true leaves appear, until then it is feeding off the stored nutrients from the seed. I have been pre-charging the DE though with a liquid organic fertilizer at half strength and a biological inoculant from the beginning with no problems. The way I look at it is, DE is like any other good soil-less medium, it has good cation exchange capacity but it doesn’t naturally contain many nutrient cations. When you add a liquid organic fertilizer, some available cations will populate the cation exchange points in the DE and the rest of the organic nutrients will be sequestered by the bacteria and fungi as food to get their life cycles going and producing beneficial metabolites that are going to help the seedling. The seedling will grab what it needs when it’s ready.

With synthetic fertilizers it’s a different story, either pre-charge with an extremely light dose or just wait until true leaves to appear to lightly fertilize.

Ray,
Thank you. I think I will do some with a pre charge and some without to see if it has an appreciable effect.