I tried starting some pak choy (bok choy) from seed, and it sprouted just great, but then after a couple days stopped growing, slowly then turned brown at the stem where it (the stem) meets the planting medium, and then died.
The planting medium is Burpees' Seed Starting mix. This stuff retains moisture incredibly well.** Maybe I in effect over-watered? The mix stayed awfully damp after initially watering in the seeds, which has worked great for tomatoes and (so far) Opo. I added no other fertilizer, etc.
**I don't know if Burpees' Seed Starting mix incorporates such, but there are hydrogels out there now that can be added to soil to pull moisture from the air not unlike the dew harvesters discussed above. I can't find the most pertinent link now (just taking a break), but will post it if I find it again later.
Or, could something else have gone wrong?
That is called ‘Damping Off’ and it happens when the soil is too wet for the seedlings, or pots and soil are not sufficiently sanitized between uses.
Common mistake. We’ve all been there, done that! :)
This is kind of technical, but you’ll get the gist:
https://extension.umn.edu/solve-problem/how-prevent-seedling-damping