Unlike planting anew, mulching is a genuine act of faith. Spring requires the effort of consistency on behalf of the waterer, but, barring any dramatic circumstances, vigorous growth is all but inevitable. Ensuring the survival of even hardy shrubs during a harsh and uneven winter, however, is a passive exercise. The sole intervention is an early enough mulching.

The act—heaping dry, shredded material around the base of a plant—is satisfying. It seems an act of protection, like tucking a lofty blanket in around a child on the precipice of sleep. But mulching works in reverse. That the plant’s root ball is going to freeze is inevitable; the layer of mulch is there to ensure it stays deeply dormant for the entirety of the season. Shrubs that wake during a mid-winter warm spell expose themselves to peril once the temperature once more plummets. I have seen accidental new growth in early January that has frozen from its branches by February and killed the shrub by March. Rather than a blanket to stave off the cold, mulch is a sedative, making the pain of inconsistency, if not tolerant, survivable.

Depending on the region, mulch takes a variety of forms, although the principle remains the same. The standard is shredded wood fiber and chips. Premium versions are natural cedar, but the majority of widely available mulch is the heavily dyed byproduct of the wood industry. Dedicated gardeners make their own with mulching equipment from accumulated prunings and clippings. My own technique has three stages, each a further barrier as the season worsens. I begin with a generous layer of cedar mulch before the first freeze, usually at the end of October. I plant decorative grass each year, but once dead, I tie-off and cut several bundles, adding those to the base of my shrubs for further loft. Finally, after the Christmas tree has served its purpose, I clip off the branches and weave those too in and around the shrubs. Thus protected from themselves, they often survive.

Grass bundles, ready for insulating shrubs.

Other tactics exist. If the shrubs are in containers, moving them nearer a shelter is effective. This is especially true of a west-facing brick wall, which absorbs daytime heat and disperses it at night. Like mulching, this is a technique to even-out inconstant temperature rather than prevent freezing. Some people drive stakes in around their shrubs, tying stout hopsacking between them to shield foliage from the bitterest winds. It is supposed to prevent leaves from bronzing, but I’d rather look out on those dreariest winter days and see some sign of life rather than bedraggled potato sacks.

But hopsacking and mulch, and not even radiating brick walls can prevent the loss of the occasional shrub. I have several planters of boxwood totaling sixteen plants in total. A winter doesn’t pass without losing at least one. I can usually say which; they are the ones that grow with less vigor in spring and fail to fill out so well through summer. They are, one might say, invisibly marked from the start. I might put faith in mulch, but the matter is obviously out of my hands.