Border control: how to keep a hedge in good shape
The secret to a good hedge is pruning little, and often, from the get-go.
It’s understandable that anyone growing a new hedge doesn’t want to prune it until it’s reached the desired height – but that’s a big mistake. The secret to a good hedge is pruning little, and often, from the get-go.
The principle of tip pruning applies to all bushy hedging species whether it’s a small, formal box hedge or a tall boundary hedge for screening the apartments next door. Tip pruning means cutting a bit off the ends of each shoot so that instead of having one single stem, you force multiple shoots to develop – usually two or three from each stem cut. As you tip prune those multiplying shoots you develop an increasingly bushy and dense plant. You never prune off much growth, but the early training makes a world of difference to the end result.
It’s easy to spot hedges that were left to grow unchecked. Those early, single shoots grow into long, unbranched stems with little foliage along them, making the hedge open, woody and unattractive. The problem is worse for very fast growing, tall species with large leaves, such as the popular sweet viburnum (V. odoratissimum). It needs frequent discipline to make it well behaved and neat. One of its cultivars ‘Emerald Lustre’ is my nominated worst-ever hedging plant because it grows so fast and so “stretched” that it’s almost impossible to make it bushy. Its huge leaves exacerbate the problem because the smaller the leaves, the tighter a hedge can be and the less obvious pruning cuts will be.
You can tip prune small plants with secateurs, targeting each growing tip, but as the plants grow you’ll move to hedging shears for efficiency. For large hedges, battery-powered hedge trimmers are brilliant as they’re lighter weight, quieter, easier and less smelly than petrol hedgers, yet just as powerful. And, unlike electric hedgers, you won’t accidentally cut the power cable.
Prune the tops and sides of hedges. Pruning off the top or terminal shoots also encourages the growth of side shoots. Keep the sides vertical or even on a slight angle (wider at the bottom) in order to maximise the light reaching the bottom of the hedge. If the lower parts are overshadowed, they’ll lose the foliage there and once gone it’s almost impossible to get back.
The best height for a hedge is only as tall as it needs to be. The taller it is, the harder, more costly or dangerous it is to prune and the bigger the shadow it casts. Along boundary fences, a 2m-tall hedge usually provides enough privacy for neighbours. To prune taller hedges without a ladder, use a battery-powered pole hedge trimmer.
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Send your questions to: helenyoungtwig@gmail.com or Helen Young, PO Box 3098, Willoughby North, NSW 2068. The best question for November wins two copies of Dream Gardens by Michael McCoy (Hardie Grant, $70 each).