Box hedge care: best practices from pruning to treating diseases
Box hedges are not very high maintenance which makes them very easy to grow. A little fertiliser and some attention go a long way and ensure these plants’ evergreen magnificence.
Generally, common box (Buxus sempervirens) is a very versatile ornamental plant. Nonetheless, there are some box hedge care rules to bear in mind. Despite being a slow grower, box needs plenty of nutrients in order to sustain its evergreen foliage and hard, high-quality wood. It also has specific water requirements and requires regular pruning to promote a dense, compact growth. Lastly, you will also need to be able to recognise and control the shrub’s potential diseases and pests. Read on to find out our top box hedge care tips to help you keep your boxwoods happy and healthy.
Contents
Fertilising box hedge
Generally speaking, fertilising box hedges twice a year is enough. In spring, apply a nitrogen-based fertiliser as soon as the plant’s growing season begins in April. In autumn, use a potassium-based fertiliser to prepare your box for winter temperatures. Organic, slow-release fertilisers are best, such as our Plantura All Purpose Plant Food. Due to its granular structure, you can easily work this fertiliser into the soil to provide your plant with nutrients for a long period of time. Our organic fertiliser is also completely harmless to humans and wildlife.
Watering box hedge
While box plants prefer moist soil, they can handle short dry spells. As the box’s many small leaves collectively form a large surface, it loses a lot of water through transpiration, so it will not tolerate extended droughts. Boxes are also very dense, especially those cut into topiary shapes, so their foliage dries very slowly. For this reason, it is important to avoid getting the aboveground parts of the plant wet when watering, because any moisture on the leaves creates a breeding ground for pests. Since boxes are evergreen plants, you need to water them in winter, too.
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Cutting box hedge
In the wild, boxwoods have a very different growth habit. But we are so used to seeing box topiary meticulously trimmed into geometric shapes that most of us might not even recognise a naturally growing specimen if we saw one. Precisely pruned boxes are probably so popular because, as humans, we delight in seeing order in nature. Our brains are also programmed to identify recurring patterns as this can help us to understand the world around us. Keep reading to get some quick tips on how and when to trim box hedges.
How and when to trim box hedge:
- Prune box during growing season from April to September, ideally on dry and cloudy days
- Use a very sharp tool so you do not squash the leaves and to prevent brown edges. Do the rough work with an electric or manual hedge-trimmer and use special box hedge shears for precision trimming
- There are three types of pruning: maintenance pruning, topiary clipping and trimming
- Carry out maintenance pruning in early spring before new shoots appear by reaching into the woody part to make basic shape corrections and for creating topiary, start clipping anytime from April
- Trim as required every four weeks by cutting new shoots to maintain the desired shape
- When attempting geometric shapes, make your job easier with anything from cardboard frames to plumb bob and line
Overwintering box
Even though box is hardy, it still requires some protection during the cold months. As one of the few truly evergreen native shrubs, box shows off its glossy dark green foliage throughout the year. On the flip side, this means that the plant loses moisture through photosynthesis even in winter. Because of this, box is more at risk of drying out, and the cold months are actually when its roots are supposed to grow the most. As a result, most of the damage the plant suffers in winter is caused by drought and not frost. Therefore, make sure to water box regularly on frost free days.
Garden soil will shield the box’s roots from frost by forming an insulating barrier. Potted box trees, on the other hand, need extra protection. Their roots tend to spread along the pot’s inner edges, making them defenceless against the temperature fluctuations. Wrap a thick layer of fleece or burlap around the pots in winter to minimise the risk of damage. To further insulate potted box plants, cover the soil surface with fir branches and place some wooden planks under the pot to protect against the ground’s biting cold. If you have a second outer pot, consider creating an extra layer of insulation between the two pots using wood wool. Moving your potted box elsewhere in winter can also help to get it through the cold months. Place your potted box in a shady and wind-protected spot outside to help it conserve moisture.
Common box tree diseases and pests
The most serious plights common to box are caused by recently introduced diseases and pests. Discover proper box hedge care for preventing infestations and avoiding pesticides in the next sections.
The box tree moth (Cydalima perspectalis) is arguably the most damaging box pest. Originating from China, box tree moth caterpillars can defoliate entire hedges undetected. Until very recently, they were spared by local predators. Luckily for us, some insects and birds have started to target these small green caterpillars and are containing the invasion to some degree. To prevent an infestation early on, inspect your box plants regularly from mid-March onwards. Keep an eye out for white webbing and caterpillars to interrupt the moths’ fast breeding cycle directly and thwart their attempt to establish themselves. Choose from a variety of biological control products to successfully contain the box tree caterpillar.
Box blight (Calonectria pseudonaviculata and Cylindrocladium buxicola) is an aggressive fungus that has been devastating whole box populations in Central Europe since 2004. Check leaves for orange, brown or black spots and stems for black streaks, which all indicate oncoming dieback. The fungicide tebuconazole may be effective against the fungus, but it harms many beneficial insects in the process. So far there is no effective biological home remedy against box blight besides calcified seaweed, which has been used successfully as a treatment for a while now.
Ultimately, the best thing you can do to minimise the risk of box tree diseases in advance is to choose a robust variety and place it in a well-exposed location. Avoid getting water on the foliage when watering and always remove any dry leaves.
