Winter mulching differs from spring mulching in that you’re attempting to protect your plants from harsh winter 
conditions – freezing, thaws and winds – by actually shielding it from the warmth of the sun. Steady temperatures help to keep your plants in dormancy and prevent them from triggering new growth during brief warm-ups.
So what can you use to winterize your beds? Try sticking with loose, insulating materials, like straw, pine needles or shredded leaves, so you can easily rake it aside and remove it come spring. If your beds don’t freeze until after the holidays, consider using cut pine boughs from your Christmas tree. Snow cover is also a great protector; and even better, requires no effort on your part!
Mulching should take place after the soil has started to harden, which is typically after the first hard frost when temperatures drop below 25°F. At this point, spread 2-4 inches of mulch around the base of your plants. Most people don’t make time for this step in the fall. However, if you’ve recently planted new shrubs, roses, etc. in your beds, consider taking this step until those plantings are more established.
The mulch needs to be removed once all threats of a hard frost are past. This can be difficult to judge, as we’ve all witnessed an occasional winter storm in April! Once thawing takes place and you can smell spring in the air (or mud), start raking and removing the mulch so the ground can begin to warm and new growth won’t be inhibited.
