My tomatoe plants have been growing indoors for 4-5 weeks. Their leaves are green and purple as I would expect. However their stem stalks are strong thick with hairs BUT where they meet the dirt are very thin and look withered. Some of them are starting to droop. What did i do wrong? I will past some pictures soon.
Yes, both of those things are conducive to the fungus problem.
Unfortunately damping off can be prevented, with good air circulation, being very careful with water, and putting a bit of cinnamon and/or chamomile (natural anti-fungals) in the water you water with. It can't that I know of be cured. Once the stems are pinched in like that, those plants are probably goners.
do we need to replace the dirt? I assume we cannot reuse the dirt which caused this? Also Can you break off the stem above the pinched color and replant? I have done that with healthy plants before. I think I will try it and report back.