Polyester Row Covers – When to cover plants

Q: On a recent radio show, you mentioned using polyester row cover to overcome squash vine borer. I purchased some but when do I cover the plants?

A: The lightweight cover prevents squash vine borer moths from laying eggs on the stem of a squash plant. Insert a two-foot tall stick beside each plant when it is four inches tall to make a “tent pole” support. Drape the row cover on top and seal the edges to the earth with clods of dirt. Sunshine and rainfall will come through the polyester but vine borer moths can’t penetrate. Keep the plant covered until you see the very first female flowers (remember that male flowers occur before female flowers). At that point remove the cover to allow visits by pollinating insects. The squash plants are large enough at this stage to resist borer infestation.