Winter Protection for Delicate Plants
Whether a plant is new to your garden and in need of some additional attention to ensure that it makes it through its first winter or you are pushing the zone limits and growing a variety that is only marginally hardy here in the USA, winter protection is something that you should be thinking about in the next few weeks.
Wrapping, mulching and mounding are the three most common techniques for protecting Delicate Plants.
The first thing to consider when planning on wrapping a plant for the winter is what the plant needs to be protected from. In most cases, we are trying to protect needles, flower buds or evergreen leaves from drying winds.
Road and sidewalk salt that blows or splashes onto plants will accelerate drying and otherwise hardy plants which can be damaged may need to have a barrier between them and the source of the spray.
Another common reason for wrapping plants is to support branches that may be damaged or broken from snow and ice load over the course of the winter.
To protect plants from wind and sun you can either wrap the entire plant or you can erect a temporary fence on the exposed sides of the plant. Fencing can be particularly effective if part of the plant is protected by structures or other plants or if there is a particular direction that the wind generally blows from. The easiest approach I have found for erecting a fence is to pound pointed 1×2 stakes into the ground before it freezes, then to go back out after the cold weather is really here, usually not until November or even early December, and staple burlap to the posts.
To wrap an entire plant I still recommend installing stakes, since wrapping directly on the plant’s foliage can result in mould problems if we have a warm winter. For upright plants, you can install tall bamboo stakes, at least 3 and more if required, and tie them together at the top to form a rough teepee structure. After the ground freezes in the late fall go back and wrap the structure in burlap starting at the bottom and spiralling up to the top.
To hold the burlap in place while you are working with it you can quickly catch it with clothes pegs or any other type of clip. I then tie some twine around the top of the stakes and burlap and spiral back down to the bottom, tieing the twine off at one of the stakes.
If you are wrapping evergreens to support their branches in case of heavy snow or ice load you can simply tie a piece of twine or cord to the base of the trunk and spiral your way up the plant, gently drawing the branches closer to the trunk as you go.
You don’t need to draw them in tight to the centre of the plant, just to bring them in far enough to reduce the area available for snow loading and to support them if snow does begin to collect. You can either tie off the twine at the top or you can spiral back down the plant and tie it at the base again. This is also particularly effective for globe cedars which can split open under snow load.
Use Clothes Pegs to secure the burlap to the stakes while you are wrapping it to keep it in place until the twine is tied on.
Mulching is an effective way to protect the roots of plants that are either only marginally hardy here in Ottawa or have been planted or transplanted after the start of September and are vulnerable to frost heave. Frost heave is caused by repeated freezing and thawing pushing the crown of a plant out of the ground and can potentially kill even hardy plants.
A loose layer of shredded bark mulch is quite effective for winter protection. Lay it down at least 4” and as much as 6” deep, ideally after the ground has frozen. If aesthetics are less of a concern straw is also a good insulator if piled up about 8” deep, but avoid hay because hay is full of seeds which will be more than happy to germinate in your garden come spring.
Mounding plants up for the winter is a technique that many of us are familiar with for protecting tender roses which can be used for a range of delicate plants. The purpose is to protect the bottom 8-12” of the rose canes so that if the winter proves to be colder than the canes can tolerate there will still be healthy stems and buds for the plant to grow back from.
You can cut the roses back to a couple of feet tall before doing this to make it easier to get to the crown to add the soil, but I generally just pile a bucket or so of soil or finished compost over the centre of the plant and leave the canes.
If the winter proves to be moderate then I simply remove any damaged or weak wood in the spring and have a larger shrub, and often more blooms, than I would have had if I had cut the entire plant back. This technique is also effective for Big Leaf Hydrangeas, Rose of Sharon and Butterfly Bushes.