Finally Mother Nature has given us a couple storms of fresh soft snow, something we always look forward to, for a couple of reasons. One is that as long as it is cold and officially winter, it is nice to have the snow for recreation and the absolute beauty of it. The other is that it insulates the ground and prevents or at least minimizes the amount of freeze thaw that takes place. As a nursery we depend on the snow to cover the plants we have stored outside in pots. Being in containers, the temperature fluctuations are much harder on the plants since their roots are near the sides of the pots. It can be deadly. The same plants in the ground however do not experience such drastic conditions. The roots are in the ground and are not subjected to such highs and lows. Any temperature change in the soil around the roots and crowns is apt to be more gradual. The snow gives us a little more peace of mind.
We do not mulch our plants in the display beds for winter protection. It is a policy of ours not to grow and sell plants that require any extra winter protection. In some cases, using a winter mulch, such as straw or boughs, has actually done more harm by encouraging voles to winter there and eat the plants we were trying to protect. We do however mulch our beds for weed control, natural fertilization, and moisture conservation. This involves adding shredded leaves and partially composted matter to the surface of the beds, to a depth of about 3”, especially the newer ones. This does not cover the foliage of the plants. Over time, leaves that fall naturally into the beds will do that job for us. We do not remove the leaves from our beds and let them become the mulch and fertilizer nature would provide had they been in a wild situation. Eventually the leaves settle in and rot, feeding the plants slowly throughout the season.
While this mulch is not intended for winter protection, it is interesting to see how it moderates and influences the freeze thaw cycle of the soil. When the first hard freezes of the fall/winter come before snowfall, the bare areas of the property are experiencing hoar frost and heaving up to a few inches high. The areas with natural mulch are not. This is very beneficial, especially for the shallow rooted plants that would be heaved out of the ground and have their roots freeze dried. A walk through any wooded parcel at this time of year will show how the forest floor is not heaving much, if at all, and the soil may not even be frozen.
So we do recommend you mulch your plants and beds for weed control and natural feeding, but not so much for winter protection. Choosing the right plants for the site reduces or eliminates the need for it, and frees you from the worry of what should or should not have been covered that really cold night.