Don’t end up like this. . .

Hedges have a long life, but sooner or later they can reach the end of that life, and become just too big. Disease may strike, or a severe storm, but the biggest problem is usually that they become too broad. No matter how tightly we trim, we end up adding a little width each year, until eventually the hedge encroaches on our garden, neighbors’ property, or public spaces such as sidewalks. Some novice gardeners try to control this by cutting back hard, leaving bare branches, but for almost all hedges this simply doesn’t work. The main problem is that all the commonly-used plants, like cedar and arborvitae, cannot sprout new growth from bare wood. They can only regenerate from wood with some foliage still on it, and hard cutting back usually means the end of your hedge. To prevent this, and keep your hedge healthy and functional for decades, it is vital to control the width before that point of no return is reached. Otherwise, you are looking at significant labor and costs removing an old hedge and re-planting, as well as several years waiting for the new hedge to grow.

Tips on Extending the Life of Your Hedge

  • Trim right from the start – to build a dense structure
  • Keep an inward sloping face – to maintain growth to the ground
  • Keep the top narrow – to reduce the risk of ice and snow damage
  • Maintain good health –fertilize regularly at the right times
  • Protect from drought – especially in the early years

If you do have to remove an old hedge, then growing a speedy replacement is usually high on the list, and that is where Thuja Green Giant steps up – the fastest thing on roots, this reliable evergreen is the number-one choice among knowledgeable gardeners to replace a hedge that has been removed. Forward planning is important, so let’s consider some ways we can extend the life of an existing hedge, one newly planted, or an older one that you have been tending for some time.

Build a Dense Structure

The biggest mistake, and the most common one too, of inexperienced hedge-growers, is to leave trimming until the hedge is as tall as you want it. If you do this the internal structure of your hedge will be weak, with a small number of very tall, straight branches reaching upwards. These tall branches are vulnerable in several ways, chiefly to bending outwards and snapping if the upper part is weighed down with snow or ice, or if fierce winds dislodge them from the hedge. Once these branches go, big spaces are left open, and the visual effect of your hedge is lost. It is hard to fill in these large gaps once they develop, and it can mean the end of your hedge.

The solution is to lightly trim the top of your hedge, beginning as soon as it is planted, and continuing throughout the growing phase of its development. This encourages lots of internal branching, so that no part of your hedge is vulnerable to opening out and creating a big gap. Any pieces that could become dislodged will be small, and smaller spaces fill in quickly from lateral growth by the surrounding parts of the hedge.

Create the Right Profile

This is the best way to extend the life of your hedge, and it is something to pay attention to from the moment you plant your hedge. The correct profile for a hedge should be a tall narrow pyramid. The base should be wider than the top, and the top should be kept as thin as possible. There are several ways to achieve this, either by free-hand trimming or using a wooden guide you can assemble at home. Even just holding up a long spirit level will show you if you are leaning inwards or not. Whatever way you choose to check it, keeping that inward lean will serve several purposes. Most importantly, it will let light reach the lowest branches, and so keep them vigorous and healthy for decades. Once the top growth widens, it will draw up water and nutrients, starving and shading the lower parts, as your plant aspires to become a full-sized tree. When you are trimming, you should expect to remove considerably more growth from the top, which is more vigorous, than from the bottom. If you aren’t, that is probably a warning that you are not trimming enough from the upper parts.

Go for a Narrow Top

The biggest danger to any hedge, especially a tall one, is breakage from snow and ice. If this builds up on the top, then it can split the growth and pull down branches.  They may in turn break, or if that doesn’t happen, be forever after prone to falling outwards and ruining the look of your hedge. Building internal structure will reduce this risk, but in addition it is important to maintain as narrow a top as possible. A lot of people pay attention to cutting the top rounded, rather than flat. This is important too, but not as much as keeping a narrow top. Rounded or square, a width of less than a foot, even on a very tall hedge, will help it survive the worst storm.

A Healthy Hedge is a Durable Hedge

A good fertilizer program throughout the life of your hedge is the best insurance against an early death. Sturdy growth, resistant to pests and diseases, and able to grow vigorously, is important not just in the years of development, but for the mature hedge too. Just as our own diet, or that of our pets, should change as we grow older, so for your hedge that high-nitrogen diet of youth should be shifter to something with more potash (potassium) in it as they age. Hedge fertilizers sold for fall use have extra potassium, and they can be used all season on a hedge that has reached its full size. You will get less extension growth, which means less trimming, and the growth you do get will be denser and more compact – better able to resist harsh weather, drought, pests and diseases too.

Don’t Forget the Water

During the establishment phase of your hedge, periods of drought mean periods without growth, so they add time to that needed for your hedge to reach the size you want. Drought also weakens the plants, and in severe cases can lead to death, even in a hedge that has been in place for several years. Although watering in fall, winter or spring will almost certainly be unnecessary after the first few years, a few deep soakings during summer dry periods will really make a difference, not just to the appearance of your hedge, but to its health and longevity too.


These are some simple, concrete steps you can take to keep your hedge growing well, and keep it healthy and trim for decades. That big job of hedge replacement can be something only other people have to think about, because you grew yours the right way.