Research done in Illinois has shown that the straw mulch should be removed from strawberry plants when the soil temperature is about 40 degrees F. Fruit production drops if the mulch remains as the soil temperature increases. If a thermometer is not available, remove the mulch as new growth starts in the spring.
Do not completely remove all the straw as there are likely to be freezing temperatures that can injure or kill blossoms. Keep the mulch between rows to conveniently recover the berries when freezing temperatures are predicted. Also, remove only enough mulch that the leaves peak through. The remaining mulch will help keep berries from rotting due to contact with the soil. (Ward Upham)