That depends somewhat on what is planted underneath the plastic. If the plants are prone to diseases that are favored by moisture on the plant's surfaces, you might want to completely uncover the plants in the morning to allow them to dry. I assume your plants are getting wet from being covered. With some diseases, it only takes a matter of ours of free moisture on the plant to get the disease started.

Plastic isn't the best material for frost protection - any old sheets or blankets will work better if you don't have regular row covers.

Any plastic that comes in direct contact with the plants will freeze those leaves just as if they had no protection at all and as already mentioned trapped humidity and heat, temperature control, proper air circulation, diseases problems, etc. can all be made worse with plastic.

If you have erected hoop houses over the plants then the best bet if you can't switch materials is to remove as much of it as possible as the temperatures allow. Good row cover materials allow for some air exchange so trapped heat and humidity isn't a problem.

Dave

Well we removed the plastic off the plants, they're growing pretty good, going to leave the cover off of them as it is warming up :) The garlic is almost a foot tall. Thanks all for the info