Before offering tips on how to prune hedges, a word is in order concerning trees that are used in hedges. No, not all hedge plants are shrubs, such as those discussed on Page 1.
Arborvitae trees have a dense growth habit that makes them popular privacy screens or windbreak trees (arborvitaes are also found in shrub-form, if you're seeking a shorter hedge). In Europe, European Beech Trees have been used for centuries as privacy screens and windbreak trees. As noted on Page 1, windbreak trees are commonly allowed to grow naturally, rather than trimmed to a particular size and shape, unless you wish to combine decorative and practical functions.
Canadian hemlocks (Tsuga canadensis) are among the easiest trees to prune into hedges. MacPhailWoods.org states, "Prune hemlock lightly but often during the first few growing seasons (two to three times from late June to late August for two to three years). After three years prune once, in late June, as with white spruce. Do not cut the leader until the desired height is reached."
How to Prune Hedges
Do not prune hedge plants so as to form a wall straight-up-and-down. Rather, prune hedges so that the base is wider than the top (a shape sometimes referred to as an "inverted keystone"). This will allow sufficient sunlight to reach the growth at the bottom, keeping it healthy. To aid you in the task of pruning hedge plants, you'll probably want to invest in a hedge trimmer. And as I relate below, you'll also need a tape measure.
How do you prune hedges so that they come out straight? And how do you get the tops level? The key is to lay out a foolproof network of guides before cutting, using stakes and string. Pruning hedges is truly a case of, "You get what you put into it." If you measure carefully with a tape measure and place your guides exactly where they should be, then you'll get a precisely trimmed hedge. But if you just try to "eyeball it," then the end-result will reflect your haste. It's that simple. Hedges are not for homeowners who desire low-maintenance landscaping.
Thus to prune hedges with precision, there's a lot of preparation involved. Essentially, the preparatory work entails framing the area (the "inverted keystone" shape mentioned above) that you want the finished product to occupy. This preparation will probably take you longer than the trimming itself. That's the bad news. But the good news is that, with the guide-strings in place, you can proceed to prune hedges with total confidence that your cuts will be unerring.
