With containment, English ivy, Hedera helix, is a dense and evergreen groundcover. As it matures, it eventually excludes weeds. Containment is very important, though. It grows fast into trees and shrubbery, and clings to buildings. On buildings, it promotes decay of wood siding and ruins paint. As a vine, it is safe only on concrete and cinder block walls.
Juvenile growth of English ivy is mostly rather compact. Ideally, it is less than six inches deep. It gets a bit deeper where shaded. Leaves are as wide as three and a half inches. Stems develop roots where they touch the soil. Adult growth is shrubby, though, and can protrude several feet higher than its support. It blooms and produces small black berries.
‘Hahn’s’ is probably the most popular cultivar of English ivy because it branches so well. ‘Needlepoint’ has elegantly narrow foliar lobes. Cultivars with yellow or white variegation grow notably slower. They are popular as foliar components in big pots of mixed annuals and perennials. Some of the hundreds of cultivars are more popular as houseplants than outside.
Nature is competitive. Competition is natural. In the wild, vegetation competes for limited resources. Where sunlight is a limited resource within forest ecosystems, competition for it is fierce. Understory vegetation does what it can in the shade of taller trees. Taller trees strive to be the tallest for more sunlight. Vines are the most aggressive competitors of all.
Vines are blatantly exploitative. They rely on trees to do the work of growing to the top of the forest canopy. Then, they climb into and over such trees to grow even higher than the trees do. Some can overwhelm and even shade out and kill the trees that they rely on for support. Strangler fig literally strangles its hosts as it develops its own supportive trunks.
Vines climb with clinging roots, twining stems, tendrils, twining leaves or hooked thorns. Some are perennials or even annuals. Some sprawl over the ground while juvenile, and then climb as they encounter support. As they reach the top of their supports, such vines generate shrubbier adult growth. Then, such adult growth can bloom and generate seed.
English ivy, for example, is a practical groundcover plant in its juvenile form. However, it becomes a clinging vine when it finds support. It quite often climbs shrubbery, trees and buildings. If left unattended, it develops into shrubbier growth that blooms and produces seed. Such shrubby growth shades desirable vegetation, and on buildings, promotes rot.
Carolina jessamine, lilac vine, mandevilla and wisteria climb by twining stems. They are generally not as potentially destructive as clinging vines. However, they can crush lattice or small trellises. Wisteria can crush substantial trellises. Like English ivy, star jasmine is likely more popular as a ground cover. It performs double duty, though, as a twining vine.
Bougainvillea neither clings nor twines. It merely produces vigorously tall canes that flop over on top of their support. Long thorns help to anchor them into place. Therefore, such canes need a bit of help to climb trellises or other support. They must be tied in place or woven into their trellises. Various other vines exhibit various and distinct characteristics.
Abundant lush foliage is actually the main asset of blood-red trumpet vine, Distictis buccinatoria, with the sporadic clusters of three inch long tubular flowers blooming as an added benefit during warm weather. Bloom can certainly be impressive when least expected though; and has a sneaky way of getting a late blast of color out during Indian summer weather patterns, when the weather gets warm after a cool phase in autumn. Contrary to the name, the flowers are more ruddy orange with yellow throats than blood red. The rich green leaves are compound, with a pair of three inch long leaflets and a three fingered tendril reaching out from between.
The vines are somewhat aggressive and can climb more than twenty feet, so need adequate support. They should not be allowed to overwhelm smaller or slower plants, or escape out of reach into adjacent trees. The tendrils can grab onto and damage shingles and light fences, but are an advantage for covering chain link fences. Given the opportunity, blood-red trumpet vine can even climb rough cinder block or stucco walls.
My niece knows the weird flowers of passion vine as ‘flying saucers’ because they look like something from another planet. The most common species, Passiflora X alatocaerulea, has fragrant, four inch wide flowers with slightly pinkish or lavender shaded white outer petals (and sepals) around deep blue or purple halos that surround the alien looking central flower parts. The three inch long leaves have three blunt lobes, and can sometimes be rather yellowish. The rampant vines can climb more than twenty feet, and become shabby and invasive, but may die to the ground when winter gets cold. Other specie have different flower colors. Some produce interesting fruit. Passiflora edule is actually grown more for its small but richly sweet fruit than for flowers.
It is certainly a star within many gardens, but it is technically not a jasmine. Star jasmine, Trachelospermum jasminoides, is actually closely related to Plumeria. Its floral fragrance can be comparably rich with copious bloom, but is distinctly vanillish. Bloom is abundant for late spring and early summer. Sporadic bloom can start early and continue to autumn.
Without bloom, the distinctly glossy foliage is handsome alone. Individual leaves are not much longer than two inches, and not much wider than one. Their deep green foliar color and lustrous sheen almost seem artificial. Pruning or any disturbance of foliage or stems releases caustic and toxic sap. Twining vines ascend by wrapping around their supports.
Star jasmine can get two feet deep as a ground cover without support. It requires pruning to prevent it from overwhelming shrubbery or climbing into trees. It also requires frequent pruning around its edges. As a climbing vine, it grows fast to ten feet high, and can grow much higher a bit slower. It can become a neatly shorn faux hedge on a chain link fence.
Bloom should be most abundant during late spring and summer. Within this mild climate though, it often continues sporadically through autumn. Japanese honeysuckle, Lonicera japonica, is presently blooming nicely in some areas. Its trusses of ribbony creamy white flowers fade to pale yellow. Although unimpressively colorful, they are alluringly fragrant.
Japanese honeysuckle here is almost exclusively Hall’s Japanese honeysuckle. It might be recognizable by a cultivar name of either ‘Hall’s Prolific’ or ‘Halliana’. Some botanists consider halliana to be a variety rather than a cultivar. (Variety names are neither quoted nor capitalized like cultivar names.) ‘Purpurea’, with dark but not purplish foliage, is rare.
Japanese honeysuckle, like star jasmine, is a vine that can be a ground cover. As a vine, It can climb more than thirty feet high. Unfortunately, it sometimes overwhelms shrubbery and small trees. Its twining stems can constrict the stems of other vegetation that it wraps around. As ground cover, it can get three feet deep. Leaves are two or three inches long.
During the 1990’s, English ivy, Hedera helix, evolved beyond small scale ground cover and became popular for pseudo-‘topiary’. It is now commonly trained onto wire frames formed into spheres, cones and all sorts of shapes. English ivy is also a nice greenery to fill in between flowering annuals and perennials in mixed urns and planters, especially where it can cascade downward.
There are all sorts of cultivars (cultivated varieties) for all sorts of applications. ‘Hahn’s Self Branching’ English ivy is probably the most practical for ground cover, since it fills in so reliably and is somewhat tolerant of partial shade. ‘Needlepoint’ had darker and more finely textured foliage; but since it does not cover larger areas so efficiently, it is instead more commonly used as greenery with mixed annuals and perennials, or for pseudo-‘topiary’. All sorts of variegated English ivy, whether alone or as a component to mixed plantings, brightens slightly shaded spots. Variegation ranges from greenish white to yellow. Leaves can be lobed, ruffled, elongated, cleft or even nearly compound; but are generally two to three inches wide. Most have three to five ‘corners’.
So many of the vines that we enjoy in our gardens might not be so appealing if we knew how they behave in the wild. Many of their characteristics that are often practical in garden situations are detrimental to neighboring plants in natural settings. If they can get away with it, vines can be just as brutal in our own gardens.
Creeping fig is perhaps the most brutally aggressive of vines. Like many other vines, it exploits trees for support. While it reaches the top of the trees, it wraps the tree trunks with a grafted network of stems that expands as it grows, literally strangling the trees that gave it support. By the time the supporting tree trunks decay, the creeping fig has developed its own self supporting trunk. Algerian and English ivies can do the same.
Fortunately, these vines rarely get such opportunities in garden situations. Nonetheless, they need to be kept out of trees that might otherwise get overwhelmed. Since they attach to the surfaces that they climb by aerial roots, they should not be allowed to climb onto painted surfaces, stucco, or anything else that they can damage.
Boston ivy supports itself by holdfast disks, which it leaves on everything that it gets a hold of. If the vines get removed to paint a wall, the disks remain. Like creeping fig and the ivies, Boston ivy, should therefore only be allowed to climb surfaces that are not likely to be damaged by its climbing techniques. Creeping fig and Boston ivy both happen to be quite practical for freeway infrastructure and sound-walls, but are difficult to accommodate in tame urban landscapes.
Wisteria is another very aggressive vine that can overwhelm small trees and shrubbery, but lacks aerial roots. It instead climbs by twining stems, which are safer for painted surfaces, but can constrict and crush light trellises, wooden shingles, lattice or anything else that that wrap around. It is certainly worth growing, but needs adequate support.
Bougainvillea and climbing roses do not climb on their own, but instead produce ‘scrambling’ canes that shoot upward and then lean onto their surroundings for support. If grown as vines, they need to be fastened to their support. If not pruned back occasionally, they can get quite overgrown and shrubby. Most varieties that are popular now fortunately stay small and manageable.
Honeysuckle, potato vine, blue dawn flower, evergreen clematis, star jasmine and the various trumpet vines are more manageable, but are still moderately aggressive. Carolina Jessamine, lilac vine, mandevilla, and passion vine are among the more docile of vines, only outdone by the annual vines like annual morning glory and climbing nasturtium.
Adult ghost ivy growth is shrubby rather than vining. Also, it blooms and produces seed.
Ghost ivy is actually just a fancy name for variegated Algerian ivy, Hedera canarienses ‘Variegata’. Their glossy six inch wide leaves with three or five ‘corners’, are irregularly blotched with dark green, very pale green and white. Like all ivies, ghost ivy can grow as a ground cover, climb like a vine, and eventually develops self supporting branches that bloom and set seed. It may be somewhat less aggressive than unvariegated Algerian ivy, but can still overwhelm perennials, small shrubs, and even small trees.
Ivy can be allowed to climb tree trunks only if it is not allowed to wrap around and graft onto itself. Otherwise, tree trunks will become constricted as they grow and expand within their ivy wrappers. Because they climb by aerial roots, the various ivies should not be allowed to climb painted or wooden surfaces that can be damaged or succumb to rot. However, some people like the look of ivy cascading down from hefty arbors and porches enough to not mind replacing rotten parts occasionally.
Contrary to the deep green of Algerian ivy, which adds a cooling effect to sunny landscapes, ghost ivy lightens up dark areas. Ghost ivy is only rarely available in ground cover ‘mud’ flats, or in #1 (1 gallon) cans. Larger plants are not practical, since they take too much time to recover from transplant. New plants are very easy to propagate from cuttings made from pruning debris. Cuttings from shrubby adult growth become shrubby plants.
Tony Tomeo 