Beginner Gardening: New transplants are not doing so well, 0 by skinks

skinks wrote:
I am new to vegetable gardening. I have had success early this season with strawberries, mesclun, and mustard greens. I just put in transplants of tomato, cucumber, zucchini and pepper. I planted these right before a heavy rain. After only 2 days, almost all the leaves on these plants turned yellow or white (see attached picture of tomato plants). The cucumber plants turned completely white, withered and are now dead - just within 4 days. With exception of pepper plants, the others plants look unhealthy and appear to be going the same route. My soil is a water-retaining clay like most in this area. I have improved by applying homemade compost and leaf mold. After putting in the transplants, I put thin layer of glass clippings on as mulch. What am I doing wrong here? Is it too much water? Is my soil the wrong ph (I did check ph today and it appears around 6)? Is there something wrong with my compost? Is it because I put thin layer of glass clippings as mulch on the garden? I don't quite know what to do next. I need some advice.