Some Veggies in my Grow-Boxes look pale

Q.  Some veggies in my Grow-Boxes look pale. These were transplanted on 4/15/ and fertilized with 21-0-0 three days later. Other than that I have been doing the weekly fertilizing. Can you let me know how to help them. One of the cucumbers died already, the rest look pale and wilted.

A.  Cucumbers and other melons and squash should not be planted until the weather is warmer – after May 15, in Salt Lake City. They do not do well in early spring.  Nitrogen should be applied immediately at the time of transplanting, and three days later Weekly Feed should be applied.  21-0-0 is not nearly as good as 34-0-0, especially in cool weather, because of the composition (NH4 vs NH3). NO3 is immediately available to the plants, while NH4 must be changed to NO3 in the soil before the plant can use it.  Did you put the proper Pre-Plant fertilizers in the soil before planting?  Fertilizing should begin after the plants come through the soil, however you must be careful not to get the fertilizer on the plant stems or leaves.  Fertilizers are salts, and will burn any plant if applied directly.  Apply four inches from the stems and then water in thoroughly.