Q. We use a white, breathable fabric for some of our tender desert plants when there’s a chance of freezing temperatures.  We’re at a 3000 foot elevation on the eastern slope of the Spring Mountain Range and temperatures can be 8° F more or less than those reported at McCarren International Airport. We go by the plant description temperatures and for 30 degree forecasts we cover those that could be damaged down to 20 F degrees. Can the fabric be left on continuously for long periods of time even though nighttime temps are higher than 32 degrees if it’s anticipated that in a week or two or more temperatures will drop again below freezing?  Some folks who sell this product say it can be left on all winter but I thought I had better check with you. Row crop cover used for cold protection for vegetable row crops  A. Yes you can leave it on! This is a major advantage with these types of products specifically made for protecting plants from light freezes. They are called by several different names including crop covers, floating row covers, frost blankets and floating row crop covers. Some background on these products will help you understand them. These covers are flexible, nearly transparent, extremely lightweight and made from fabrics that are typically spun or woven. They “breathe” allowing light, rain and air movement through them but still capture heat coming from the ground. They transmit so much light that there shading effect on plants is only somewhere around 15 to 20%. They gained fame primarily in commercial vegetable production about 30 years ago for two distinct reasons; protection of vegetables from light frosts and earlier production. When left on permanently during cool weather, they can raise air temperatures under the fabric about 5 to 6° F which causes vegetables to grow faster which in turn means they can be harvested earlier. Besides protecting young tender plants from freezing temperatures and growing faster, they also provide another valuable advantage; insect protection. In organic production they are a valuable asset to leafy greens that can be damaged from wind, intense sunlight or chewing insects.             Row crop covers are placed over new seedlings or transplants and kept from blowing away with metal staples and a soil covering the edges. They are also used as a covering for low tunnels used in vegetable production.