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Niagara-on-the-Lake
Wednesday, September 28, 2022
Growing Together: ‘Tis the season to be pruning your evergreens and shrubs
Make individual cuts to keep a natural form.
Make individual cuts to keep a natural form. Joanne Young

Early to mid-June is the best time to be pruning your evergreens.

Pruning seems to be one of the most frustrating and the most misunderstood areas of gardening. The longevity of a plant is determined by how well it has been pruned over the years.

It is always best to prune your conifers yearly to stay within the size and scale of most landscapes.

The biggest mistake people make is they wait until the shrub has overgrown its space and then they try to hack it back to keep it smaller. Let it be said that “hacking” is never a proper pruning technique.

Evergreens come in all different shapes and sizes – spreading, rounded, upright, pyramidal and weeping. The natural branching pattern of the plant dictates its shape.

By respecting this inherent form when pruning, it is possible to limit the size of the plant without changing its form. Not only does this preserve the plant’s true beauty, but it saves the expense of replacing overgrown plants.

Do not buy a pyramidal-shaped plant thinking that you can keep it pruned into a globe shape. You will just have a very unhappy looking globe. You need to work with its natural shape.

Here are some things that you need to understand before you start pruning your evergreens:

  1. Evergreens retain their foliage year around. They compensate for this by losing their oldest growth every year. That is why you will always see brown needles or foliage in the centre of your trees and shrubs. This also applies to broadleaf evergreens such as rhododendrons, hollies and euonymus. Most evergreens will hang on to their needles or leaves for three to five seasons.
  2. Unlike deciduous trees and shrubs, most evergreens will not rejuvenate themselves if cut back to old, bare wood. Yews are the main exception. Most evergreens grow primarily from buds set the previous year and have few, if any, latent buds. It is generally safe to prune back only to one- or two-year-old growth, which still has existing buds. Do not prune back into branches where there is no growth.
  3. It is almost impossible to rejuvenate an old, overgrown evergreen. Therefore, it is important to prune yearly and not wait until the shrub or tree has become too large. This way you can slow down its growth so it does not overgrow its space quickly.
  4. Most evergreens push out new growth only once or twice a year – late spring and possibly again in late summer. Best time to prune most evergreens is after the new growth has emerged in late spring to early summer.  On most evergreens, the new growth emerges a lighter colour. Once the colour has faded to the same colour as the older growth that is the best time to prune. You could do a second pruning at the latter time, but not too late into the fall because it will stimulate new growth that will not have time to harden off before winter.

There are two main goals when pruning evergreens:

Control Size of the Plant

We usually choose the plants we do because we are attracted to the natural shape of it.

When it comes to pruning them, though, we will take our shears and cut the tips of each branch to the same length. If this is how you are pruning, you will find that in a couple years all your plants have the same dense blob-like form.

You will have lost that character of the plant that first attracted you to it.

To keep a more natural look, make individual cuts with the secateurs and not with the shears. This is called natural pruning.

That means you are making selective cuts to thin or reduce the overall size of the plant. This cannot be done with shears, but with secateurs or loppers.

It means cutting one stem at a time and not just shearing off the tips. When pruning is completed, it should look like no cuts have been made; It should still have its natural form.

Maintain a Certain Shape

The other goal of pruning evergreens is to maintain a shape such as a hedge, pyramid, globe form or specialty shapes like spirals and pompons.

This is best achieved by shearing. With shearing you are just removing new tip growth, creating a full dense look. Even though electric shears make the job easier, hand shears make a much nicer job of things.

Electric shears just tear the plant tissue while hand shears make a cleaner cut. When the plant tissue is torn there is more die back at the tips, giving the sheared shrub a brownish cast.

To prevent this from happening, always make sure any pruning tool is sharp and clean. To achieve a more formal, sheared, geometric look shear up to three-quarters of the newest growth each year.

This way you are only allowing it to grow, say, an inch per year instead of four inches per year.

Happy pruning.

Joanne Young is a Niagara-on-the-Lake garden expert and coach. See her website at joanneyoung.ca