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Plantland Home & Garden

Prince George, BC, Canada

Gardening Tips

What you Need to Know When You Don't Have a Green Thumb

The Importance of Bark

Growing Orchids

This time of year, when deciduous trees and shrubs have no foliage, it is the bark that becomes the focal point. Bark is an essential part of a tree, not only is it attractive, but it also serves a purpose as it protects the tree, and provides the tree with the important nutrients and moisture it needs to grow. This is why it is important to protect a trees bark by using tree guards, especially over the winter months when rodents are hidden under the snow and eat the bark of the tree. If a tree’s bark is deeply eaten in a continuous band (girdled), chances are the tree will not survive.

Bark covers the outside of the tree and its branches, and is made up of several layers. The outer bark (epidermis) protects the inside of the tree. It protects the tree from insects, fungi, moisture, drought, wind and sun, and during the winter months it insulates from the cold and in summer from heat.

The inner bark (phloem) is how the tree gets its nutrition. It is like a pipeline transporting nutrients made by photosynthesis from the leaves of the tree, and carries it to the branches, trunk and down to the roots of the tree. It is short lived and when it dies it turns to cork and becomes part of the outer bark.

The cambium is a thin layer between the inner bark and the xylem. It is the growing layer producing cells that allow the phloem and xylem to grow. This is the layer that produces a new growth ring every season.
The Xylem is the fourth layer and youngest layer. It is responsible for bringing water and nutrients up from the roots of the tree to the leaves and branches.

 

Bark is needed for a tree to grow but it can also add to a winter or year round landscape. There are many hardy deciduous trees and shrubs that have interesting and attractive bark, which is something to keep in mind when choosing trees/shrubs for your yard. Some shrubs such as the red twig dogwood adds bright red colour to a white snowy landscape. For bright red colour, prune out one-third of the older branches each spring to promote new bright coloured growth. Winged Burning Bush has interesting corky ridged branches that catch the snow. Ninebark is a deciduous ornamental shrub that gets its name because it has several layers of exfoliating bark, which is an attractive attribute over the winter months. The Amur Cherry is known for its glowing golden brown to dark red bark with a glistening finish which peels, and Pin cherry has attractive red/brown bark, while Birch trees are known for their white bark. A tree that I enjoy is the Bur Oak which has corky bark and twisted branches.

Bark also has another use in the landscape in the form of bark chips. Bark chips are spread in a thick layer on the ground between plants as a decorative ground cover. Not only do they add to the landscape, but they also help keep weeds down, and keep the soil moist.

As you go out and enjoy the outdoors, take the time to appreciate the beauty of nature and the importance of bark.