Answer: The snow will serve as a mulch of sorts. The times to worry are in spring and fall when the soil freezes and thaws and as a result may cause plants to be heaved up out of the ground. A mulch can help the soil stay at a more even temperature. The mulch would be applied around the plants and over the root zones but not over top of the crowns. If you want to apply it later this spring, wait until the snow is melted and you can see what you are doing.
A clean layer of mulch such as fresh straw beneath the plants can also help keep soil from splashing up onto the berries. An organic mulch is also very useful during the summer because it smothers weed seeds and helps keep the soil cool and moist.
You are correct in that in spring, when the plants are blooming, it is important to protect the blooms from frost or freeze damage as this will ruin the berry crop. Some gardeners will keep a light mulch such as straw available to cover the plants on cold nights, another option is to use a synthetic frost blanket made specifically for that purpose. The blankets are easier to put on and off and lighter weight types can be left in place during the day as well.
Q&A Library Searching Tips