In this video, I pull out some of the transplants that are too weak to survive and replace them with celery transplants.
Celery is hard to grow in Houston because celery prefers 4.5 months at 60-70 degrees. Nevertheless, ordinary celery planted in mid-November will usually produce a large crop of fair celery in spring, but all at the same time. Without protection, they will be killed by freezes below 20 degrees (info from Dr. Bob Randall, "Year Round Vegetables, Fruits and Flowers for Metro Houston).
The store I mentioned in the video is Mid County Farm and Seed store. Betty was incredibly helpful and knowledgeable about gardening. Here is their Facebook page: https://www.facebook.com/midcountyfeed