Gardening with Peter Bowden: Protecting Perennials

Lack of snow during the depths of winter can cause big problems for our hardy perennials. As the soil freezes, ice forms. Water expands as it becomes ice, and this forces the soil apart. Frost heaves are an amazing force of nature. Frost heaves are capable of shattering asphalt roads and buckling concrete as they grow. Repeated thawing and freezing and heaving can push bulbs and shallow rooted perennials out of the soil. This is pretty rough on the plants as you can imagine… tiny roots have no chance against the unstoppable force of ice. 

What we really need right now is a nice blanket of snow to stop this destructive cycle. The term “blanket of snow” is very appropriate. Once the soil is covered with a few inches of snow, the soil stops heaving plants out of the ground, and they can stay safely frozen in place. 

We are about to enter the coldest six weeks of winter. Unless we get some significant snow soon this is going to be a very rough winter for our perennial gardens and shrubs. The only way to help is to cover the soil with something to shade the ground from thawing sun and protect the crowns of our plants from drying arctic winds. Straw would work, but it blows around and is a mess to clean up in spring. Burlap could work as well, but that would be an ugly and expensive solution… there must be something better. Let me think… there must be something… evergreen boughs would be perfect!!! 

Christmas trees to the rescue! With the holidays past, there’s no shortage of evergreen material to scavenge to cover our perennial beds. Abandoned Christmas trees can be gathered from friends and neighbors and provide the perfect mulching material. This seems a more fitting end for an evergreen tree rather than getting kicked to the curb as our attention wanders into the new year.

The first step is to strip the boughs from the tree with your loppers. You can get quite a few boughs from a single tree. Layer them like roof shingles over your beds with the twig end facing into the wind.

Start with the perennials that are the most exposed. Don’t cover the beds too deeply with evergreen boughs; just enough to shade the soil and provide protection from drying winter winds. We’re not covering our beds to keep them from freezing. On the contrary, they need covering to keep the soil frozen over winter and especially during any “false spring” weather in February or March. Our hardy perennials are capable of withstanding freezing. What CAN damage them is repeated thawing and re-freezing. 

The layer of evergreen boughs shades the soil so the beds won’t thaw too early in spring. If this winter provides enough snow to keep the ground covered, my layer of mulch won’t be needed since the snow will protect my beds. But I’ve learned not to trust the weather, and if the winter continues to be lacking in decent snow cover, I’ll be glad I’ve got them covered so I can enjoy the primula and other perennials when the growing season returns. 

Thanks for the read!