Jen, the undersides of my plant leaves were purple because they were propagated in a pretty cold environment (25-50 degrees). Once the sun hits them for a few days, the dis-coloration will be gone. My brassicas did the same thing, no biggie....

EG

My tomato plants also turned purple when I put them into my cold frame. (I contributed it to colder temps.)

The colder temps did what I wanted, which was to slow the growth and make the plants much stocky and hardy. Now that the weather has warmed up considerably, my tomatoes have greened up nicely. With the next few days being very warm and very sunny, I can't wait to see what kind of growth they put on in the next week!

Thanks guys. I'm not really worried about it, and I'm sure cold temps in the basement is a factor. I just wanted to find out if everything had righted itself in the end. I'll hit them with the same diluted fish/seaweed fertilizer that I'm using for my peppers anyway.