Why do we wrap trees and shrubs in winter? It seems to be a northern tradition. Every fall we go out and wrap plants in burlap to keep them protected from winter weather. All the books and all the web sites tell us to do this, so it must be right? Let’s have a closer look.
Why Cover Trees and Shrubs in Winter?
There are several stated reasons;
1) Keeps plants warmer
2) Reduces moisture loss
3) Keeps deer away
4) Protects from ice damage
5) Reduces salt damage
6) Looks good
7) Protects from sun
Let’s have a more detailed look at each of these reasons and then decide what approach we should use.
Keep Plants Warmer:
This topic has been dealt with in a previous post. See Are Wrapped Trees Warmer in Winter for more details. Wrapping plants in winter does not keep them warmer.
Reduces Moisture Loss:
This topic was discussed in Keep Plants Warm in Winter . Reducing moisture loss is important for some plants and a wrap can reduce moisture loss.
Keeps Deer Away:
This is certainly true. Deer eat just about anything when they are hungry. They leave my Yew alone all summer and early winter. By late winter they come and have a meal. A wrap of burlap keeps them from eating the new growth from the previous year. I also cover some small shrubs with chicken wire if I suspect they will eat them (eg sumacs) until these plants get big enough to fend for themselves.
The wrapping in the picture above looks silly–only the bottom of plants are wrapped. But it is a good way to reduce deer damage provided the wrapping goes as high as a deer.
Protects From Ice Damage:
People who live in the north understand the damage an ice storm can cause. In a few hours branches of trees and shrubs can be covered with a very heavy layer of ice. The weight of the ice can break branches or bend them dramatically. Most deciduous plants will recover and fill in the broken spaces. Some evergreens, especially upright evergreens like junipers can be so severely deformed that they never look good again.
Wrapping with burlap can prevent ice damage. It keeps the branches close together so that the ice can’t bend them over.
Salt spray from the road can be damaging to some evergreens. Covering them can help.
In most cases, the covered plants do not look good. The above picture is an extreme example. To be honest most coverings make your front lawn look terrible.
Protect From Sun
Most shrubs and trees do not need to be protected from sun in winter, but there is at least one group of plants that will benefit from such treatment. Some of the newer yellow-leafed evergreens, brown very easily in winter from drying and sun damage. This is mostly an issue for 2-3 years after planting. Once the plant is well established it is less sensitive to sun and drying. So if you plant such evergreens it is a good idea to wrap them, in winter, for 3 years.
Issues With Plant Covers
There are clearly some good reasons for covering your trees and shrubs, but there are also reasons for not covering them.
1) Moisture issues
2) Rodent problems
3) Sun scald
Plant covers reduce wind and therefore reduce loss of moisture from the plant. The same covering however can also cause problems with too much moisture. Many plants that are native to cold regions of the world like to stay dry in winter. This includes most deciduous trees and shrubs, as well as all perennials. Excess moisture can cause them to rot.
You have made a nice cozy spot for your plant and rodents think that is just marvelous. A nice place to spend the winter, and plant food to eat – better than the Holiday Inn.
Some coverings, like clear plastic, act like a greenhouse. When the sun shines the temperature increases significantly, and this can damage the plant. If the temperature gets too warm it can scald the plant. Lower warm temperatures make the plant think it is spring and they start to grow. A few days later it gets very cold again and the plant dies. Once a plant has cooled down for the winter it is best to keep it cold until spring.
Should You Cover or Not?
If plants are covered correctly, none of the above mentioned issues should be a problem. Covering plants does provide some benefit, however, I would suggest that except for the deer issue and the yellow leafed evergreens, very few plants need to be covered. If you don’t plant upright evergreens with very vertical branches, you really don’t have an issue with ice storms. If you select plants that survive winter in your zone you will not need to protect them. Spend a bit more time selecting your plants rather than spending time covering them each year.
I garden using a fairly simple philosophy. Make gardening easy and fun. Covering your plants is extra work. If you select a plant incorrectly and it gets damaged in winter or even dies, the solution is simple. Plant something else in it’s place. With many thousands of plants to choose from why struggle with a lemon?
1) Photo Source: Buffalo Spree–A Magazine of Western New York