The boundary hedge of the property I have just bought is badly overgrown. It seems to be a mixture of hawthorn, sloe, nut bushes, and some other plants. Can I cut it back hard without harming it, and, if so, when?
Yes—a hedge made up of a mixture of deciduous plants like this can be cut back by at least half its height, provided it is healthy and vigorous. The time to do this is between October and March, and it will result in new growth appearing from lower down and from the base, thus helping to fill up gaps, as well as making the hedge a more manageable height.
Can I cut down hard a conifer hedge which has gradually got too tall over the years?
Conifer (and other evergreen) hedges have to be treated gently when it comes to renovative cutting. It is not wise to cut hard, as this may kill them; this is specially true of the cypress family. Instead, it would be better to cut a little extra off each year when you do the routine clipping until it is down to the height you want.
I have cut down hard my rather neglected hedge, which had grown too tall. What should I do now to help it grow well again and fill in the gaps?
Starting at one end, work along both sides of the hedge, removing long side-shoots and any which are broken, dead, or diseased. Then thoroughly clear the base of all rubbish and remove any weeds completely, by hand if possible, but chemically if necessary. Fork the soil along both sides, and apply a dressing of well-rotted organic matter; add a general fertiliser dressing the following spring. Cutting it down hard will encourage new growth from the base to fill in the gaps.