There are a couple reasons this might be happening.
The most likely culprit is heat. If plants are too close to light sources they will become droopy. The same can be said for plants that are too cold. The ideal temperature range for most crops is 65 to 85°F.
It could also be a result of overwatering. If plant roots are starved of oxygen the leaves will begin to droop and wilt. Allow the growing medium to dry out before watering.
A more serious problem could be bacterial wilt, fusarium wilt or verticillium wilt—these are fungal and bacterial diseases. The symptoms of each include wilting leaves and stems. There are other symptoms involved such as yellowing leaves. There is no cure for these diseases. One can only remove the infected plants.
I hope this helps clear things up.
Sincerely,
Matt LeBannister
