This week, in between a lot of other work, I have been planting 210 ivies and still have 40 more to go.... So now that I have got ivies on my brain, let us have a look at this versatile and easy going plant.
Ivies (Hedera spp.) are an exciting group of vining plants that are gaining more attention these days. This genus contains about 15 evergreen species from Europe, Asia, and northern Africa, and is a member of the family Araliaceae. Accomplished climbers, ivies can tackle almost any surface using their aerial roots to cling on as they make their ascent. Not only can they be used to cover vertical surfaces and grow up trees, they also make efficient ground covers. While these fast-growing plants can provide quick coverage of unsightly walls and surfaces, they need to be pruned and controlled or they have the potential to become invasive.
The English ivy, Hedera helix, is perhaps best known for its evergreen foliage that is often used as a groundcover year-round. In addition to the English ivy there are a number of other species of true ivy. The best known are: Hedera colchica, also known as Persian ivy, Hedera hibernica, also known as Irish ivy (this is one of the fastest growing varieties and is great if you want quick results), Hedera rhombea, the Japanese ivy, Hedera nepalensis, the Nepal ivy, and Hedera pastuchovii, the Russian Ivy.
But some plants called ivy are really not ivies at all. The Boston ivy, which is used in northern climates to cover buildings, belongs to the genus Parthenocissus, turns red in the fall and loses its leaves. It is not evergreen. Most of the other plants labeled as ivies are plants of tropical origin and are commonly used as houseplants. This group of so-called ivies includes: grape-ivy (Cissus rhombifolia), German-ivy (Senecio mikanioides), Swedish-ivy (Plectranthus oertendahlii), and Kenilworth-ivy (Cymbalaria muralis). Poison-ivy (Rhus toxicodendron) is also not a true ivy.
Ivy foliage usually takes on its adult shape when it can no longer grow any taller, and cuttings taken from this wood will produce a shrubby form. The thick leathery leaves can be unlobed, 3-lobed, or 5-lobed and variegated or dark green. Borne in clusters, the flowers are small, and of little interest to all but their fly pollinators. The berries that follow are usually black or dark blue, looking a bit like blue berries.
Traditionally, ivy is also used indoors in winter to create attractive Christmas decorations and festive wreaths. Gold and silver-leaved ivy can be draped over Christmas trees to make attractive and natural alternatives to tinsel.
As a rule, ivies are not fussy about climate or soil type. However, ivy prefers well-drained, slightly alkaline soil. If your soil is acidic, add lime. They will grow in almost any soil that is not waterlogged, and in any aspect from heavy shade to full sun. Light, pale yellow and silver leaved varieties prefer partial or full sun. Dark, green-leaved varieties are ideal for growing up north-facing walls. Ivies also make excellent indoor pot plants. Propagate from cuttings, which strike easily at almost any time of the year.
Watering: Water thoroughly but infrequently. When the soil feels dry, gently add water to the soil until the surface is totally wet. Then do not water again until the soil is almost dry. If grown in pots - do not allow pots to stand continually in water.
Fertilizing: Since foliage is the main feature of ivies, use fertilizers high in nitrogen (the first number in the fertilizer formulation) to provide good green growth. Do not use fertilizer when plants stop growing either in the heat of summer, or when temperatures are cool.
Pruning: Prune in spring or early summer to check and control the plant's vigorous growth.
Problem solver: Ivy is not usually susceptible to pest or disease problems. But on the other hand, vigorous ivy can cause structural damage to houses and wall surfaces with its aerial roots. It can also damage gutters and paintwork, attack house foundations and smother and kill trees.
To kill over-vigorous ivy, cut through the growing stems and apply ammonium sulphamate to the trunk. Owing to the glossy nature of ivy leaves, herbicides applied to foliage are not usually successful. Remove remaining aerial roots in brickwork with a wire brush. Wear gloves when pruning ivy, as the sap can irritate skin.
Marc Vijverberg Photos: Forest & Kim Starr, Hawaii