Dig it – December Tips from the Secret Gardener

Holly

Holly Ilex aquifolium is one of the plants most strongly associated with Christmas but this well-known evergreen with its glossy, spiky leaves is also a useful resource for butterflies and moths.

Holly branches have long been used to decorate homes in winter but it is considered bad luck to cut down a whole tree. Holly was seen as a symbol of protection and everlasting life due to the evergreen flourishing when other plants seemed dead or dormant. In Christian custom Holly stands for the crown of thorns and the berries for Christ’s blood.

Holly is a native tree or shrub that can grow up to 23m. Many cultivars exist with leaves that are spineless or variegated yellow and green, or with yellow berries.

Holly is dioecious, meaning that male and female flowers occur on different trees, so if you want to have berries then you will need to have one of each. The white flowers, in late spring and early summer, contain nectar which attracts pollinating insects. Once pollinated, female flowers develop into scarlet berries that can remain on the tree throughout winter or until they are eaten by birds such as Blackbird, Redwing and Fieldfare.

Holly Blue on HollyAs the name implies, some Holly Blue butterflies will chose Holly bushes in sheltered, sunny positions to lay their eggs. There are actually two emergences of Holly Blue each year – the first from mid-April to June and the second in late July and August. The tiny, white, disc-shaped eggs are laid singly at the base of flowerbuds or the very young fruit of various shrubs and hatch after about two weeks. The plain green caterpillars from the spring generation feed predominantly on the flower buds, berries and terminal leaves of Holly and can complete their development entirely on leaves of male Holly bushes, although female bushes are preferred. The summer generation mainly feeds on Ivy Hedera helix.

There are several moths which could also use Holly in your garden, depending on where you live.

Yellow-barred Brindle caterpillars feed on the leaves flowers and buds of Holly, Ivy and other plants. Double-striped Pug caterpillars feed on the flowers of many plants including Holly and Ivy.

The micro-moth Holly Tortrix Rhopobota naevana feeds on many trees and shrubs including Holly and at the opposite end of the size spectrum Privet Hawk-moth caterpillars have occasionally been reported to consume it too.

Holly is a versatile plant which can be used as a specimen plant or in a hedge. It can cope with cold and drought and most soil types except when waterlogged. It is easy to care for, needing little attention and responding well to hard pruning so you could happily take a few branches to make a Christmas wreath.

Happy Christmas!

The Secret Gardener