The tomatoes are too large to cover any longer. I did put the covers back over the lettuce 1/2 of that row and the row without any tomatoes. (It stormed over the weekend.)
(From Mid March)
This garden is in a sheltered area with a fence and a road to the north. It is on a hill top so less affected by cold. . I used a light weight insect barrier which provided enough protection and day time heating to promote growth. There are garden fabrics that provide additional frost protection down to 26-27 degrees. (Search Agribon garden fabric.)