Specifically, in the information I read, it said: "be sure that you make sure that you 'harden off' the seeds before transplanting". I live in Phoenix, AZ, and have grown the seedlings on my covered porch since January but would now like to replant them on the porch into containers and grow them on a trellis. Do I need to still "harden them off" since they have already been growing in a 40-90 degree climate? I'm not sure what "hardening off" means.
Transplanting Butternut Squash From Seedlings
Certified GKH Gardening Expert
You mention that you are growing your plants in a covered porch. Hardening off the seedlings involves moving them slowing to the outdoor environment.
They need time to adjust to the sunlight, wind and temperatures.
Move them to a sheltered area a few hours a day and get them used to the change.
Here is an article that explains this important step in the growing process.