Ok, so I started my okra inside about 4 weeks ago. They did great! My seedlings transplanted well with very little stress. But now...

1. They're stuck at 4" tall.
2. The leaves are yellow during the day (new growth leaves) but bright green at night.

I have them in a well draining container that is fairly large (5 gallons) and they're not crowded. I used 50% compost and 50% potting soil. Its in a sunny and hot part of my yard so I don't know what gives. Please help. any ideas?