Tender plants will not survive cold winters, though they may be perennials. By overwintering them, a gardener keeps the plant protected and alive to replant it outside the following spring. Clearly, this is easiest done with potted plants. But plants can also be transplanted from the garden into pots each fall before the first frost. Some plants can be left in the ground if a cold frame --or (in more temperate climates) a cloche or plastic grow tunnel-- is placed over them before cold weather sets in.

the phenomenon of SPB larvae remaining in the tree through the winter months.

Overwintering (also called hibernation) is a condition in which an animal is dormant for period of time. Some butterflies and moths overwinter during cold weather.