The first post shows the cotyledon being affected and the same with the last photo - but these are the seeds itself and its suppose to drop off. If the true leaves are affected then you have a problem. The pea plant = looks like it's been affected because there was a period it didn't get any water and then suddenly watered. A case of inconsistent watering. Was that the case? The one thing you should watch for is a fungus called DAMP. It kills suddenly. the entire plant just dies out. Once a plant is afected, throw it out before it infects the others.there's some anti damp treatments available at garden centres. However once this thing takes hold, it's very difficult to manage. Best to throw out affected plants and to treat unaffected plants. Do not over water the plants. Also keep your plants well ventilated using a fan (gentle cycle). I usually add a little layer of sand on top to prevent these things from happening.

But...but...but... it's only baking soda! Is it bad for seedlings? I read somewhere that they use baking soda spray for gnats and other tiny insects. Re the black fungus, my camera can't show it very well but in the last photo, the tiny leaf is black on one side. I'm thinking of separating them from the rest of the healthy seedlings. I hardened them the past few days although yesterday, we had a lot of rain so I wasn't able to take them out. Maybe it wasn't as gradual as I thought? Because I left them out the whole day today. The medium is compost with dried rice husks. The cups have holes on the bottom and drain fairly well.

Thanks for your input! I potted the 3" seedlings (with one or two sets of true leaves) into Solo cups (and a few yogurt containers) with soil up to the leaves. So the stems were buried deeper when I transplanted. I put the roots right at the bottom of the cup (with a little soil under) and then filled up to the leaves. Some have room left to add more soil as they grow (most are maybe 1/2 to 2/3 full of soil). They are not touching the cold windows - they are in a sunny south window, a few inches from the glass. I have some other ones that are at least 12-18" away from the window and they have same symptoms. It's at least a month before they can go outside. I have been plucking off the dead foliage and am definitely hoping they'll grow out of it (and that it's not disease that's going to spread!). The top soil looks dry, but they are watered regularly from the bottom. I water when the cups feel light, usually every 2nd day or so. I've added a couple more pics showing the whole plants.

Hey ZM I'm hoping that you get this...I'm going on the assumption that you are... OK, I've become what you warned me not to...a Mad Scientist! Balancing the Miracle Grow with the Neptunes Harvest (my community garden is organic so I'm smuggling in the Miracle Grow) with my Physon 20., has become a whirlwind of measurements and applications. I use the teaspoon of Physon 20 with a gallon of water when I do the whole garden but I use A TBL when watering diseased plants. I'm still a little nervous about mixing the P 20 with fertilizer. Im using MG on some and NH on some and am experimenting with ratios. My little munchkins still refuse to grow. They're healthy and some even have buds but they're no taller than 6 or 7 inches. I fertilize them daily but...nothin' That's not entirely true. My Zinnia Envy has grown...not as tall as they should be but I think they will keep growing. Do you think I should keep going with the little guys a or chalk them up to an experiment with indoor seed starting and try to do better next year. Also, you said you used Silicone for plant strength (at east I think that's what you said). My Zinnia stems are bending. Do you think that the Silicone could help them stay upright Anyway...just checking in Thanks ! Dale