i only use worm castings as fertilizer until my seedings are well established. has worked well so far. 
You just put the worm castings at the top of the media, or do you mix it in? Or are you using pure worm castings?
I think the temps are getting too cold at night, when your not there and the lights are off. Which makes mildews much worse and doesn’t help, maybe you can make a tarp or some plastic and divide the basement up and put a fan on in the lighted up side and open a vent or leave a door open to the house. I have had to resort to space heaters or bringing heat from the house for seedlings before but definitely air movement is a must.
For seedlings grind up the pure castings into fine dust and apply over the top. If you get some on the plants shake or spray it off.
Definitely no osmocote for a seedling mix, id toss to the side for trees and remake your media. Worm castings and some other organics are different and don’t cause issues
The reason I’ve shied away from organics for containers is because I’ve read that the necessary microorganisms to release the nutrients in organic materials don’t exist in an indoor environment.
I think its almost impossible to be entirely sterile unless your in a enclosed environment and even then its easier to let the good guys populate the area and crowd out the bad guys. Worm castings usually contain a pretty diverse microbiome and i view beneficial fungi and bacteria as neccessary for container gardening to provide the huge missing links that are outside. I feel possibly why people finding the stuff doesn’t work are just possibly buying dead microorganisms? Local live worm castings are a great way to get a diverse innoculation and they work great on seedlings. I always have had good luck with mycorrhizal and beneficial innoculants and you should definitely see them work (Fungal webs, improvement in the soil and beneficial bacterias usually just make plants happier by reduced nutrient deficiencies and leaves aiming up). I feel you definitely have bad fungi or bacteria around and you should crowd them out when you start seedlings and right now you probably need a Trichoderma or bacillus subtilis / pumulis product to attack that rot if the seedlings are salvageable.
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Good info. Thank you!
i mix a handful into my potting mix. i prefer to use pure coir , perlite and a little castings but any well draining mix will work. put the seeds on the surface and crumble just enough castings to just cover them. water lightly. i only mist the surface with a water bottle until they are about a 1/2in. high then i give a 1/2 dose diluted kelp/ fish emulsion fertilizer every other watering. i water deeply every 3 days or when the surface is completely dry. i also take them off the heat mat now. i find a fan oscillating in there helps keep molds and fungus at bay. don’t have it blowing directly on them. just above them on low. learned this trick from a friend that grows medical cannabis.
I am positive your soil medium is to anaerobic, even with proper drainage your just not able to air where it counts. The solution it to let the soil dry out and rehydrate with 3% hydrogen peroxide. (from the dollar store). Yes it will bubble, no it will not hurt your plants.
You can also buy it by the gallon but if you need that much then I suggest buying 35% and diluting it 1:11 peroxide to water. Wear latex gloves it burns.
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Peroxide? Really? Never heard of that!
Good old simple H2O2 its used as a topical disinfectant at the 3% level. You will find it rite between the bottles of rubbing alcohol and which hazel.
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To clarify - I know what hydrogen peroxide is. Never heard of using it for plants!
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well other people read the replies too.
https://airneeds.com/how-to-sterilize-soil-with-the-hydrogen-peroxide/
hydrogen peroxide has many uses pertaining to gardening as i mentioned in post#2 one of the best uses for seedlings is helping to fix overwatering by adding oxygen to the soil. when overwatering occurs it displaces all oxygen in the soil. i buy it buy the case and have been using it more years than i can remember. it also helps to eliminate fungus on the tops of pots that have been overwatered.
it helps with 02 but won’t it also kill off beneficial bacteria and fungi? i can see its usefulness in starting seeds but on larger plants, i would think it would cause more issues.
One treatment wont kill everything. Right now the issue is everything is dying cant get much worse.
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So you are suggesting using straight 3% - but the links posted suggest diluting even the 3% quite a bit…so I’m not sure the best way to go.
1/2 cup per gal sometimes more is what i use when i need to. i do not use it on large potted plants just seedlings.
if you are going to use it you need to use it when your media has dried out quite a bit from the pic above.
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The original source I used said 3% but you would only want to do that once. otherwise you will overkill the microbe population.
you still have to dilute 3% h202 and never ever worried about using more than once. i would use it as much as i needed to fix the problem.
It seemed to work. I did the H2O2 and it seems to have stopped the decline.
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