Leaves in Our Vegetable Garden are Turning Yellow

I planted my garden two weeks ago, and the plants looked fine. Now all of them have turned yellow around the edges of the leaves, vegetables, and flowers. I carefully covered everything up the nights the frost were predicted. Any help would be greatly appreciated. The plants are still standing erect. I don't have to replant everything do I?

Hardiness Zone: 5a

Mary from Charlotte, MI