How to trim your hedge
On side shoots only, cut back new growth by two thirds. Leave main stems to grow until the hedge reaches the desired height. The only way to rejuvenate an irregular, patchy or misshapen hedge is with radical hard trimming and then reshaping. Take care with conifers here though, as they will not put out new growth if you cut them all the way back to the wood. The only exception to this rule is the yew, which can withstand even brutal pruning.
Do be aware that some plants, such as thuja and yew, can trigger allergic skin reactions, so you should always wear gloves when trimming these hedges.
The ideal weather for hedge trimming
Do not trim your hedge when it is too hot or sunny, as there is a danger that the freshly cut surfaces will dry out and die. The same applies if it is too cold, so if when spring comes you are still regularly experiencing sub-zero temperatures, do not trim your hedge: the cuts will take a long time to heal and the cold will weaken thinner branches.
How to trim your hedge straight
For a good straight cut, it’s helpful to have a guide edge to follow that runs parallel to the hedge. This could be the edge of the lawn or a kerbstone – or alternatively, you could put up a taut string between two stakes to keep you in line. Hold the hedge trimmer level as you work. You should step back every so often to check from a distance how the hedge is shaping up – this makes it easier to see if you are actually trimming straight or not.
A wedge for your hedge
For a lush look from top to bottom, go for a slightly wedged shape when trimming your hedge: wide at the bottom and narrow at the top. This is to ensure that light reaches the lower branches, otherwise they will lose their leaves for good. In any case, always ensure that the hedge is not wider at the top than the bottom, as if the bottom is too narrow it will suffer from being constantly in shade.
Trimming and pruning young hedging plants
When you plant a new hedge, it doesn’t need trimming initially. In its second year after planting, you can trim the hedge back to the shape you want. Leave the main stem alone until the hedge has reached its intended height, and cut all other stems back by up to half.
Filling gaps in your hedge
The solution for improving fullness in the appearance of a hedge is generally simple: plenty of light. Small gaps will quickly close up if they get enough light – so remove some surrounding branches or other growth that is shading the gap. For a larger space, fix a bamboo cane or other support across the gap and tie a nearby branch into it. The trained stem will follow the cane and grow in place.
Collect green waste
After hedge trimming, remember to dispose of the clippings. If leftovers remain on the lawn, they will obstruct its growth and may result in bald spots. It is best to sweep the green clippings together with a fan broom or remove them with a cordless blower, such as the STIHL BGA 56. Alternatively, before trimming the hedge you can spread out a textile underlay such as an old bed sheet to collect the green clippings. This saves a lot of work, especially in hedges with very small leaves such as boxwood, because the cuttings can be collected and disposed of so easily.