I have been trying to grow tomatoes in pots since I was a kid. They just never do as well as in the ground for me. On the seedlings, it has been hit or miss. I have been doing it since I was about 12 and I have only had one year where they did super from seedling. I keep a good routine of care, but some years they are doing well and in the matter of a few days I will lose almost every one. Not sure what it is unless it is because I do not use a warming pad under them.
Lose them to what? Fungus? Just failure to thrive?
I never use any kind of warming pad. I just make sure they get enough water, re-pot into bigger containers as they need, and fertilize them. Tomato Tone is a good product. They seem to like fish emulsion too.
No clue. They just start keeling over.
No black rot spots?
Are they getting enough water? They drink a lot you know.
Tomatoes really aren't that hard -- they almost grow themselves as long as they have enough to drink. The only problems I've had here has been when it rained incessantly several days in a row and they got fungus. But that's easy to see happening.
They need all the sun you can give 'em too. I don't have a lot of sun here but I moved them around to follow the sun through the day when I was home and had them potted. They lived well into November.
What about your seed source? Have you tried another source?
I'm very particular about seeds but it's mostly to avoid any chance of Frankenseeds (GMO).
You can give tomato plants tobacco mosaic if you smoke around plants or handle them after smoking...
I buy one Husky Red Cherry and one Grape Tomato early.
I put them under a 24 hour grow light, and take cuttings.
I had nine plants last year, and made tens of thousands of tiny, tasty tomatoes.
90% of what I grow goes to critters.
Crows love me, and there is always one watching over me.
If I put out tablescraps, they are on them in 2 minutes.
They even find brown eggs out in the brown grass.
I'd worry about the food I buy and then throw away, if it didn't keep the critters so happy.
Crows love them some eggs!!!