Diatomaceous Earth as a seed starting medium

[Jaysan]

I was wondering the same thing. What the local autozone had here up front was not DE.

I had to look around to find that.

[JamesL]

I got a 15lb bag of Ultrasorb at Autozone.
25lb bag of Optisorb at Fastenal.

[Delerium]

Item #8834. I am sorry i mislabeled the weight. 25 lb bag for 6 bucks. Still a bargain and works the best for me. I really didn't like the finer DE. I tried Ultrasorb a few times and stuck to the cheaper brand ever since.

[RayR]

Originally Posted by Delerium

Item #8834. I am sorry i mislabeled the weight. 25 lb bag for 6 bucks. Still a bargain and works the best for me. I really didn't like the finer DE. I tried Ultrasorb a few times and stuck to the cheaper brand ever since.

You're right, Moltan 8834 is coarse DE. Must be the same thing as OptiSorb. Autozone's website says it's unavailable and they also have the wrong MSDS for it that says it's clay.
That's a lucky find at your local store, especially at that price for a 25lb bag which is like half price.

[RootLoops]

nice find! i just ran out of mine it'll be at least a week before i can get more i'll look for that

[ChrisK]

Interesting because this has not been my experience. In fact, I have a pot of seedlings in pure DE that damping off is racing through right now. It has been the bane of my seed starting this year regardless of what I try.

About the only thing I haven't tried is a pre-sow soak in bleach to eliminate any seed borne inoculum.

Originally Posted by b54red

I now plant seed with little doubt that I will get great germination and will have little or no problem with damping off anymore.

Bill

RayR, the kitty litter I get from Dollar Tree is 100% DE- states it on the bag- I have used it for years as an addition to my garden soil & container soil for aeration improvement.

[JamesL]

Originally Posted by ChrisK

Interesting because this has not been my experience. In fact, I have a pot of seedlings in pure DE that damping off is racing through right now. It has been the bane of my seed starting this year regardless of what I try.

About the only thing I haven't tried is a pre-sow soak in bleach to eliminate any seed borne inoculum.

Chris,
Have your tried hydrogen peroxide?

[ChrisK]

No, might give it a shot. First is a bleach soak plus a bit of detergent which will surface sterilize the seed.

For those interested, here is the progression of the disease caused by any number of fungi. You can clearly see the necrotic lesion starting in the middle seedling and the rotten stem on the right as the disease progresses.

Originally Posted by JamesL

Chris,
Have your tried hydrogen peroxide?

[RayR]

Originally Posted by ChrisK

Interesting because this has not been my experience. In fact, I have a pot of seedlings in pure DE that damping off is racing through right now. It has been the bane of my seed starting this year regardless of what I try.

About the only thing I haven't tried is a pre-sow soak in bleach to eliminate any seed borne inoculum.

Can you post some pictures of the damping off? I think we would all be interested in seeing it since there have been no other serious reports of damping off in DE. Oh, I see you already did before I posted.
Did it happen on any specific varieties or just random?

Originally Posted by JoParrott

RayR, the kitty litter I get from Dollar Tree is 100% DE- states it on the bag- I have used it for years as an addition to my garden soil & container soil for aeration improvement.

So I've heard from a few folks that their local Dollar Tree has Blue Ribbon DE. I've never seen it in any Dollar Tree store up here ever, all they carry is Soft Paws, cheap clay stuff.

[b54red]

Originally Posted by ChrisK

Interesting because this has not been my experience. In fact, I have a pot of seedlings in pure DE that damping off is racing through right now. It has been the bane of my seed starting this year regardless of what I try.

About the only thing I haven't tried is a pre-sow soak in bleach to eliminate any seed borne inoculum.

I can induce damping off in seedlings started in DE by keeping it too wet; but that is the only time I have had a problem with damping off with DE. I always use just straight tap water and bottom water my small containers (egg carton cells) then plant the seed and cover with a very light layer of DE and then remove them from the water. I don't give them water again until the DE starts turning white and then only bottom water for just long enough to dampen the DE again. Whatever you do, don't leave your planting containers in the watering tray any longer than necessary.

The few cases of damping off I had were due to me getting distracted and leaving planting containers in the watering tray and leaving it for hours or longer. The only other thing that will bring on some damping off is to water them when they don't need it. I plant in egg cartons because they give me the perfect size container to work with the DE. I only use the UltraSorb brand from Auto Zone for seed starting. The DE dries out in the egg cartons in a few days so the DE doesn't remain too wet for very long. Are you using deep containers or large containers to start your seed? A large or deep container may keep the DE too wet for too long encouraging damping off. Are you using UltraSorb brand?

I spent years trying everything to prevent damping off down here and nothing worked until Ray posted about the DE. I used hydrogen peroxide, bleach, and various fungicides to little avail. One of the biggest problems I have now with damping off is when I am grafting. Trying to get my grafts to stay in a healing chamber long enough to heal without getting damping off is nearly impossible. No matter how sterile I make the environment it isn't enough because the stuff just seems to be in the air down here and give it too much moisture and it will flourish. By using fresh DE when I pot the grafts to go into the healing chamber I have reduced the problem but that damp environment is just asking for it.

Try not to bury your seeds too deep because they only need the slightest layer of UltraSorb. Make sure to only water when necessary and for as short a time as it takes to wet the DE and your damping off problems should get much better.

Bill

[ChrisK]

It seems to come and go here for me and I can't correlate it to anything I'm doing. Some rounds were perfect in my normal peat:perlite mix, some rounds absolutely everything died just after I saw the hypocotyl peaking through!

Usually I have more than I know what to do with and I have to put them out with a "free" sign and this year it was a struggle to get what I wanted. Never had this problem in my many years of propagation. Most frustrating is I went through a lot of my F2 seed from crosses.

Originally Posted by b54red

I can induce damping off in seedlings started in DE by keeping it too wet; but that is the only time I have had a problem with damping off with DE. I always use just straight tap water and bottom water my small containers (egg carton cells) then plant the seed and cover with a very light layer of DE and then remove them from the water. I don't give them water again until the DE starts turning white and then only bottom water for just long enough to dampen the DE again. Whatever you do, don't leave your planting containers in the watering tray any longer than necessary.

The few cases of damping off I had were due to me getting distracted and leaving planting containers in the watering tray and leaving it for hours or longer. The only other thing that will bring on some damping off is to water them when they don't need it. I plant in egg cartons because they give me the perfect size container to work with the DE. I only use the UltraSorb brand from Auto Zone for seed starting. The DE dries out in the egg cartons in a few days so the DE doesn't remain too wet for very long. Are you using deep containers or large containers to start your seed? A large or deep container may keep the DE too wet for too long encouraging damping off. Are you using UltraSorb brand?

I spent years trying everything to prevent damping off down here and nothing worked until Ray posted about the DE. I used hydrogen peroxide, bleach, and various fungicides to little avail. One of the biggest problems I have now with damping off is when I am grafting. Trying to get my grafts to stay in a healing chamber long enough to heal without getting damping off is nearly impossible. No matter how sterile I make the environment it isn't enough because the stuff just seems to be in the air down here and give it too much moisture and it will flourish. By using fresh DE when I pot the grafts to go into the healing chamber I have reduced the problem but that damp environment is just asking for it.

Try not to bury your seeds too deep because they only need the slightest layer of UltraSorb. Make sure to only water when necessary and for as short a time as it takes to wet the DE and your damping off problems should get much better.

Bill

[b54red]

Chris I can understand your frustration. I dealt with it for years and years but it all boils down to moisture levels. Peat and other seed starting mediums would just soak moisture out of the super humid air here and no amount of fans or fungicides would prevent damping off except during those very rare times when the humidity would be lower. I used to plant whole trays of just one variety in order to get one seedling and sometimes that didn't even work. I knew I was in trouble if after a few days the surface wasn't dry in my containers. I ended up setting them outside if possible just as soon as they started sprouting to get the drying benefit of more sunshine and wind but even that wouldn't work when the humidity stayed around 100% or it was rainy.

The first time I used UltraSorb I was very skeptical and over planted as usual and lost almost no seedlings to damping off. I was still not sure of it until I had planted numerous times when conditions were ideal for damping off and yet I still rarely saw it except in the cases I mentioned in the above post. Another thing I noticed was far higher percentages of germination especially with difficult to germinate seed like spinach and cilantro.

Bill

[ChrisK]

Adding another anecdote to this thread. The pic below is a comparison of my peat:perlite blend vs Ultrasorb. It's obviously way too small for any kind of statistical comparison. The same genotype from the same packet of seed was sown on the same day. Egg carton was then placed on my seedling heat mat until emergence was noted.

The ultrasorb plants emerged 3-4 days later and are clearly behind their siblings in the peat mix at this point.

[JamesL]

Chris,
Do you have any fertilizer in the DE?
I have a similar observation with respect to growth and I made sure to put it in my notes for next year. I didn't really notice a difference with germination, but I do pre-germinate all my seed.
Growth was definitely slower without the "spurts" you typically see. Slower growth was beneficial to me with respect to grafting though, enabled me to get better matches.

PS - I did do a side by side of DE pre-charged with SeaStart 0-4-4 and without. No differential in growth to true leaf stage.