Manage root weevils on rhododendrons, hydrangeas, azaleas, primulas, camellias, and strawberries with Cold Shots. Cold Shots is a non-toxic biological control, effective down to 5℃. It covers 10-20 medium to large shrubs (or 130 square feet) and contains six million predatory nematodes. The application window is in April when soil temperatures are greater than 5℃.