Strawberry plants are hardy perennials that will reward you with lots of sweet fruit for up to four or five years when properly cared for. Winter is very important to strawberry plants for fruit formation, but temperatures that drop below about -8 degrees C (17F) can kill the plants. Protect strawberry plants from harsh winter cold to keep them healthy.
Watch for weather forecasts of frost beginning in late autumn. As long as the temperatures are not forecast to fall below -8 degrees C (17F), several exposures to light frost will benefit your strawberry plants. They will "harden off," or gradually become more able to survive cold weather. Once frost threatens, stop watering your strawberry plants until the following spring.
Prepare to mulch before the need actually arises. Spread a generous layer of hay in the furrows between the strawberry plants. Use enough straw to mulch the rows of plants 10 to 15 cm (4 to 6 inches) deep.
Fork or rake the straw mulch onto the strawberry plants when lower temperatures are predicted and the plants have undergone two or three hardening-off frosts. Cover the plants completely, but shake the straw as you apply it to eliminate heavy chunks that could smother them. Don't remove any snow that falls on the mulched plants, as snow is actually a natural mulch that will further help to insulate them.
Fork or rake the winter mulch into the aisles between the rows of plants when new leaves begin to develop in the spring. Don't remove the mulch from the aisles until all danger of frost has gone.
Repeat mulching onto the plants and into the furrows between them when dangerous spring frosts threaten, particularly if the strawberry plants have begun to flower.