DECEMBER
Plants of the Month
Hedera helix ‘Glacier’
Hedera helix ‘Parsley Crested’
Hedera colchica ‘Sulphur Heart’
Myths about ivy abound, particularly in regard to the supposed threat it presents to trees and buildings. Ivy is not parasitic: when it climbs trees the rootlets do not penetrate the bark, although when the plant reaches the top of a tree it may become dense and act like a sail in high winds. Dead or diseased trees may break or fall as a result, which is perhaps nature’s way of culling the old to make way for the new. On damaged buildings, ivy makes things worse, but is otherwise beneficial: research shows that it keeps walls 15 per cent warmer in winter and 36 per cent cooler in summer, protecting masonry from frost and pollution. Of the myriad cultivars of H. helix, variegated ‘Glacier’ is one of the best.
Not all ivy leaves are ivy shaped – there are lots of interesting forms to seek out, and ‘Parsley Crested’ boasts beautiful crinkled edges to its glossy foliage. ‘Tripod’ has very narrow three-lobed leaves making it look just as its name suggests, while ‘White Ripple’ has finely pointed leaves in grey-green edged with white. Interestingly, ivy produces two distinct forms of growth, juvenile and adult, which are often present on the same plant. The juvenile form has threeto five-lobed leaves, grows in a twining fashion and clings to its support. After a couple of years, the plant enters adulthood. Leaves lose their distinctive shape, stems thicken and the plant becomes more shrubby and produces flowers and berries.
This species is also known as Persian ivy and tends to have bigger, more leathery leaves with less finely defined lobes. It makes a vigorous and quick-growing climber, ideal for covering a wall fast if you have an eyesore to hide, but, like all ivies, it’s more than happy kept trimmed to size. ‘Sulphur Heart’ is one of the most readily available cultivars, its leaves broadly splashed with lime green and gold. H. colchica ‘Dentata Variegata’ is similar, except its variegation is creamy-white. Like H. helix, when it reaches adulthood Hedera colchica produces flowers that are a very valuable late source of nectar for pollinating insects, and are followed by inky-black berries that are loved by birds.
128 A YEAR IN THE ENGLISH GARDEN
IMAGES SHUTTERSTOCK; ALAMY
With its fantastic wildlife benefits, diverse shapes and forms and cunning growth tactics, ivy is in a league of its own
