Ilex is the botanical name for holly, the evergreen forms being very useful for hedging and screening, especially as they are tolerant of quite hardand trimming. I. X altaclarensis is hardy and evergreen, and will in time attain a height of 9m (30 ft). It is particularly useful in seaside areas, owing to its ability to stand up to salt-laden gales. I. Aquzfolium is our native English holly. It does not grow quite so tall – 7.6m (25 ft) – but has the advantage of yielding the familiar red berries for Christmas decorations.
Male and femaleare borne on separate plants and the berries appear only on the female plants, but some male plants must be grown nearby to fertilize the females, although there are one or two ‘feminist’ varieties of I. aquifolium that can produce berries without male intervention. There are a large number of named varieties of both these species of holly, with variegated and different colours of berries, but for a number of reasons they are not entirely satisfactory for screening or hedging. They are slower growing, and do not grow so tall, need sun for their leaves to variegate, tend to revert to all-green, and are generally more difficult. I. Crenata is a Japanese holly sometimes used for low hedging – it grows to about 1.2m (4 ft). It does not have the typical prickly holly leaves, and bears black berries.
General care: Holly will tolerate any aspect and soil, although it prefers some moisture at its. Plant in May, about 60cm (2 ft) apart for hedging and at least 1.2 m (4 ft) for screening. Make sure you plant some males to fertilize the females if you want berries. If you are planting on an exposed site, erect small screens of polythene sheeting or hessian to protect against the prevailing wind until the young plants are established. Trimming and pruning should be done in April.
Propagation: Take small heeledin September from that year’s growth and strike in a 50-50 mixture of peat and sand. Alternatively, layer some shoots in October or November. In either case, wait two years before putting the young plants into their permanent positions.
Pests and diseases: Birds take the berries, and are difficult to stop. Small spots on the leaves can be caused by fungi, and if troublesome should be sprayed with a fungicide.