Shoveling in single-digit temperatures after the colossal winter storm this weekend, I dumped mounds of snow onto my garden beds, knowing it would protect my trees, shrubs and dormant perennials. Snow protects your garden beds like winter mulch. Trees might need some help though When the ground repeatedly freezes and thaws, as it does over winter in cold climates, that can squeeze roots, seeds, bulbs, tubers and rhizomes right out of the earth. Once exposed, they can be killed off by cold, drying winds. But snow cover provides a heavy blanket of winter mulch that insulates the soil, prevents heat from escaping and keeps soil temperatures from seesawing. And as it melts, snow will not only water your garden but fertilize it with plant-boosting nitrogen absorbed from the air on its way to earth. It’s a perfect display of nature taking care of itself. On the downside, the same heavy blanket that keeps plants warmly tucked in can spell disaster for evergreen trees like arborvitae and Leyland cypress. When wet snow accumulates on trees, its …