After the holidays, when the ground is solidly frozen, is the best time to apply winter mulch. As a seasonal bonus, discarded Christmas tree boughs can be used as a terrific insulating layer. The idea here is to create a stable micro-environment around the roots of the plant in order to prevent the soil from heaving during freeze and thaw cycles. Roots do not like to be pulled and pushed, ripped and torn! The micro-environment under the mulch layer buffers against the effects of severe and sudden temperature changes, allowing the plant to ease along through the winter season.
Tops on my list for winter mulching is the "New Dawn" rose. After its run-in with Hurricane Sandy, it's been reduced to a stand of bare canes.
Best of all, this mulch is free and, for a brief period, widely available as folks haul their old trees to the curb for pick-up. Yes, you don't even need to make use of your own Christmas tree! Typically, we celebrate around a table-top tree--this year, a dwarf Alberta spruce--which can spare no branches. So yes, I'm that person who's leaning over her neighbors' discarded trees with a pair of clippers in one hand and an armful of cut boughs in the other. It's all in the holiday sharing spirit, right?