Hedera helix, English ivy, is a well-known, evergreen, woody vine that is either well-loved or well-hated (depending on the type of garden) for the species' indomitable ability to rampage across the southeastern landscape regardless of the challenges of a given site. There are hundreds of cultivars of English ivy that have been selected for differing leaf size and shape and a lovely range of variegations including creams, whites, golds and even pinks. Many of these named forms are significantly less rampant growers and far better behaved choices for small gardens where they are excellent choices as both groundcovers and climbers. There are few things as readily able to lighten up the dark corners of a wooded garden as well as a white or gold variegated ivy slipping up the tree trunks.
If you have had the pleasure of training English ivy up a tall wall, tree trunk, post or fence, you may have noticed an interesting transformation that occurs as the vine grows into the upper reaches of the vertical. The characteristic pronounced, sharply three-lobed shape of the leaf begins to blend into a narrow heart-like shape. You may have also noticed the emergence of small, starry flower clusters late in the summer that punctuate the upper reaches of the vine with lacy haloes of gold, eventually maturing into handsome, (but poisonous!) inky black fruit. What you have seen is the rather amazing transformation of the vine from its juvenile to its adult physiological state. This fascinating change in character is triggered in Hedera by the vine growing a certain vertical distance from its roots (although a romantic friend of mine prefers to think of it as the vine falling in love with the tree and thus proclaiming its state of ardor with heart-shaped foliage and humble presentations of little bouquets...).
Adult English ivy offers different landscape character than its youthful form. The adult leaf shape is less bold and more refined than the juvenile leaves. The flowers and fruit are subtly handsome in late summer, and are especially striking against the leaves of variegated forms as the blue-black fruit sprinkle a marvelous contrast against white-splashed foliage.
Gardeners can purchase adult ivy from specialty nurseries without waiting for a planted vine to achieve this form in the canopy of a tree. Once a vine attains the adult form, it can be propagated and grown so that the propagated plants start out as adult form plants. Adult forms tend to develop an attractive, shrubby type habit but they must be given the opportunity to remain upright in order to retain their adult habit. If planted at ground level with no vertical surface nearby, and allowed to sprawl downwards, they will quickly revert to the juvenile form with sharply lobed foliage and no flower or fruit production. Adult form plants are beautiful in the corners of walled gardens and other small spaces. In the Victoria era in England, many cultivars of adult ivy were produced and available commercially but they are rarely available today. Old specimens of globose shrubs 6-10 in diameter exist as well as true hedges of adult ivy (one can be seen in the herb garden at the US National Arboretum).
One of the advantages of adult ivy is that it is generally slower and more manageable than juvenile forms while remaining tough and adaptable in a range of sites. Although it prefers moist, high organic matter soils, it will thrive in most soils, from wet clay to light sand, and is quite salt tolerant. Both adult and juvenile English ivy will also perform well in an amazing range of light conditions from full sun to dense shade with variegated forms retaining best foliage quality in at least part shade in the intense sun of the southeast. In the southeastern US, English ivy is completely hardy from the coast to the mountains but needs to be in a protected site in the mountains to avoid winter damage. It can be propagated from cuttings almost any time of the year that will root best if treated with rooting promoters and rooted under mist.
One can often find adult forms of English ivy perched in large oaks around older, established gardens of the southeast, but there are many other ways that adult English ivy can add elegant lustre and refined beauty to difficult, tight urban gardens. Gardners with a special interest in ivies of all types may want to contact the American Ivy Society, c/o Mr. Bill Redding, PO Box 520, West Carrollton, OH 45449-0520. Even if English ivy is not on your top ten list in general, adult English ivy is well worth hunting for in specialty nurseries, and certainly a very good reason to climb the walls.