Garden doctor

Shares tips on rejuvenating and caring for different types of hedges

How to give tired hedges a revamp

Whether we plant them ourselves or inherit them, hedges have a greater longevity than many other elements of the garden. They do a fine job of defining boundaries, dividing spaces, casting shade, providing wildlife habitats and setting the tone of our gardens. However, left unmaintained they can run wild, turning back into the large trees or shrubs nature intended; and in the process become thin, holey and bare at the base. To avoid this, regular maintenance, trimming and selection of appropriate species is paramount. Broadly, hedge cutting should be carried out at the following times: Leyland cypress, Lawson cypress, yew and Thuja (white or western red cedar) – late spring and again in late summer/ autumn. Privet and box – two or three times during the growing season, and beech and hornbeam once in late summer. Keeping up with this routine will ensure dense hedges, clothed to the ground so long as you aim for an ‘A’ shape in profile rather than a ‘V’. But, if your hedge is overgrown there are a number of solutions. Yew, Thuja, hornbeam, privet, Prunus and beech can all be rejuvenated over a two- to three-year period. The bulk of one side of the hedge can be cut back to within 20-30cm of the trunk in year one. In year two, the cut side will begin to rejuvenate. In year three, the uncut side can be reduced back in a similar manner to the other side. And in a further year’s time you’ll have a slim dense hedge. Leyland and Lawson cypress are not quite as amenable – unlike the other hedges they don’t have ‘dormant buds’ in their old wood so a hard cut back will disfigure or kill them. The only option is replacement. I’ve never planted a Leyland cypress hedge, simply because Thuja is a superior hedging plant, albeit a little slower to grow. It, like other suitable hedge species, such as holly, pittosporum and Elaeagnus × ebbingei, work well because they produce vigorous side shoots once their growing tips are cut off. This is because hormones produced in the tips inhibit the growth of lower shoots so their removal leads to more stems, more foliage and a thicker hedge. I avoid species with lanky growth, bare bases, large internodes and slow growth, along with those that won’t rejuvenate from cutbacks. Keep your hedge healthy Annual feeding of both deciduous and evergreen species will keep them energised while their growth is being regularly cut. Choose a fertiliser high in nitrogen and phosphate to encourage strong roots and foliage. Products containing bone meal and seaweed work well, along with a good mulch. Also watch out for pests and disease. Many can be avoided with good feeding and watering but the most common pests – scale, aphids and thrips – can be controlled with organic insecticides from garden centres. In terms of diseases, powdery mildew may occur in very dry soil but can be remedied with regular watering. Box blight is perhaps the most significant fungal disease. Affected parts can be removed and burned but recovery is never guaranteed. Whichever hedge you choose to grow, keeping up those regular trims will ensure dense ‘living walls’ furnished with foliage.