hedge archwayThis week’s Gardeners’ Question Time looks at how and when to trim hedges. The question comes from Anne Elk who lives in West Devon:

‘I never seem to be able to get an even, level cut on my hedge when I give it its annual trim. How can I achieve a really neat appearance?’

Well Anne, first you need to check on whether in fact your hedge is of a variety that does just need only one clip, or whether it should have several (see below). If it’s the latter, it will be difficult with only one cut to keep it smooth and sharp as so much material will have to be removed, so you should perhaps be trimming it more frequently.

In general though, to get a sharp, level shape when cutting, stretch a string line tightly between two posts along the top, at the height you want the hedge to be, and clip exactly to this level – however, be prepared to repair any accidental cutting of the string! For the sides, put in canes vertically at intervals along the hedge, and sight along these as you cut. Alternatively some people can do this by eye and achieve a satisfactory result, especially if the hedge is fairly low.

Lowish hedges can eb trimmed by eye as long as a good original line has been established

Lowish hedges can be trimmed by eye as long as a good original line has been established

So how and when should you cut different types of hedge?

Established deciduous hedges that are moderately fast growing (e.g. Beech, Hornbeam, Hazel and Tamarisk) should be trimmed once in August – however, if they are growing particularly well, they might need two trims – one in late July the other (lighter trim) in early October.

Deciduous hedges which tend to be fast growing (e.g. Blackthorn, Myrobalan Plum, Hawthorn) will need about three clippings at about six weekly intervals during the summer- this also applies to some fast growing evergreen hedges such as Lonicera and Gorse.

Some slower growing evergeen hedges such as the various Laurels, Elaegnus and Sweet Bay require just one cut in early autumn, though faster growing evergreens such as confiers are best trimmed once in August – or possibly twice if particularly vigourous (once in July and then again in early October). For Yew, trim once a year in the summer.

For slow growing, smaller – leaved evergreen hedges such as Box, you should be cutting in early summer (June- July) and again in late summer/early autumn (including topiarised shapes).  Box hedges should be cut in overcast weather as if they are cut in the hot and dry their half cut leaves will desiccate and turn brown. For Privet (Ligustrum) you will need at least two and possibly more cuts in a season to maintain its shape.

Mazes are often created from Yew hedging - usually an annual cut will keep it looking trim

Mazes are often created from Yew hedging – usually an annual cut will keep it looking trim

If you have an informal flowering hedge, in general this should be pruned rather than generally cut over. This is best done in spring if it flowers in between mid summer and autumn and in mid summer if it flowers in the spring or early summer. In both cases take off the shoots which have flowered, thin out the growth if it is crowded and remove completely any old growth which is straggly and flowering badly.

For most hedges try to establish sloping sides with a taper inwards towards the top (known as a ‘batter’) – this encourages growth lower down the hedge which if the sides were vertical (or even worse sloping inwards towards the bottom), would result in thin growth at the base where less light reaches the leaves.

Not all hedges are meant to be level and straight- 'cloud pruned' forms such as this are more a work of art than a geometric challenge!

Not all hedges are meant to be level and straight- ‘cloud pruned’ forms such as this are more a work of art than a geometric challenge!

I hope that you find this of help, and if you have any gardening questions that you think I might help with, then please email me at nbold@btinternet.com

Old School Gardener

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