Growing Vines Successfully

Vines are a diverse group of plants. Most are easy to grow and require little care; however, a basic knowledge of their cultural needs is important for success in your garden.

If you're unfamiliar with the USDA Plant Hardiness Zone system, find out your zone from a local nursery. While you should take the USDA zone recommendations seriously, remember that location, like politics, is local. Within each USDA zone there are always microclimates that are warmer than the surrounding, larger region. But don't forget that a microclimate, especially one that is shady or exposed to wind, can also be colder than the encircling area.

Some of the most spectacular vines, such as bougainvillea and passion flower, are also tender—unable to tolerate cold temperatures. Because of their height, even hardy vines can't take full advantage of snow cover, as perennial flowers can. Attempting to sustain marginally hardy species of vines is an endless

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Make sure your vine gets all the sun or shade it needs. Full sun means at least 6 hours of direct sunlight daily. [Photo: Robert Hyland]

In addition to matching a vine to its region, you must match it to its site. Light is a crucial element. Sun-demanding climbers, such as coral vine and roses, may survive in partial shade, but they won't thrive—and won't produce many flowers or fruits.

Make sure that your vine gets all the sun or shade it needs. When gardeners talk about full sun, they mean more than six hours of direct sunlight each day. A site in light shade gets some direct sun and some shade during the day, or bright, filtered light throughout the day. Full shade means no direct sunlight. Don't forget that some vines—silver lace vine is one—prefer full sun in northern regions but may want partial shade in hot parts of the country.

As a group, vines are vigorous growers and do best in organically rich soil. That doesn't mean heavily amending the planting hole: Recent research indicates that over-enriching a planting hole discourages roots from growing beyond the hole, slowing the plant's growth. Instead, turn over a shovelful of soil. If you find earthworms, the soil is in good shape. But if your soil contains a lot of sand or clay—or is seriously lacking in nutrients—you should improve it. In all cases, the solution is to add compost, composted manure, or other organic matter.

The great majority of vines aren't particular about soil pH. There are exceptions, however. Plant a wisteria in highly alkaline soil and its leaves turn yellow. If you have reason to think your planting site is extremely acidic or alkaline, do a pH test before you plant, and select a vine suited to the site.

Planting Vines

When to plant vines depends on where you live, what species of vine you've chosen, and whether your plant is container grown, bare-root, balled-and-burlapped (B&B), a small, tender transplant, or if you're beginning with seeds. The goal is to make sure that a good root system develops before the vine is stressed—by low temperatures in the North, or by high ones in the South. Bare-root vines should be planted at the same time as perennial flowers, shrubs, and trees—typically in spring in cold regions, or in autumn in warmer climates. Container-grown climbers can be set in the garden throughout the growing season, as long as you water them regularly (and provide shade, if necessary).

Dig a hole that is at least twice as wide as the root ball, but only one or two inches deeper. Gently remove a container plant from its pot (once out of the container, handle the vine by the root ball), untangle any girdled roots, and place it in the hole. It should sit at the same level or very slightly higher than it was growing in the container (an exception is clematis). Water the root ball generously, allow the water to drain, and then fill the hole with the soil you removed, tamping it firmly around the root ball. Cut back the plant to encourage branching, and finish the job by mulching with 1 or 2 inches of compost or other organic matter.

Handle B&B vines the same way. The traditional advice is to leave the burlap in place—removing any wires, cords, or other ties—but there is some evidence that roots develop more quickly if the cover is removed. Moreover, today's burlap may contain plastic threads, which will prevent the vine's roots from expanding. If removing the burlap is difficult, consider loosening it or slicing it several times with a knife after the root ball is in place.

Hardy bareroot vines should be planted as early in spring as the ground can be worked. Cut away any dead or broken roots, then soak the roots in water for 8 hours. Leave several inches of loosened soil in the bottom of the planting hole. Set the vine at the same level it was growing (the stem will be discolored, giving you a guideline), refill the hole with the soil you removed, and mulch.

Gardeners often start annual vines from seed indoors, then transplant them outside once the danger of frost has passed. If you've begun other annual plants, you know the regimen. Use a soilless mix to avoid "damping-off," a fungus that attacks seedlings. To speed germination, provide heat: Either place the planting container—a 3-inch pot is ideal—in a warm location, or set it on a heat mat or heat cables.

As soon as the seeds germinate, move their containers to a bright, airy, cool location. Water as needed, keeping the soil moist but not soggy, and feed every 10 days with a liquid organic fertilizer applied at half strength. If you've sown several seeds in one container, thin to one plant by cutting (not pulling) the ones you don't want.

Harden-off the seedlings two weeks before the expected transplant date by moving them outside to a sheltered location for a portion of each day. Leave them out a little longer each day, exposing them to increasing amounts of sun and wind, until they are fully acclimated to the outdoors. If you choose to purchase annual vines, they, too, should be hardened-off before they are planted in the ground.

Many annual vines, such as morning glories and sweet peas, grow rapidly enough that they can be sown outdoors. Follow the seed-packet directions, and remember that planting, transplanting, and setting-out time is also trellis time. Don't postpone installing any support your vine may need in order to climb—do it when you set out the plant.

Maintaining Vines

Food: Vines that are planted in fertile, organically rich soil and mulched once or twice a year with compost normally do not need to be fertilized (for information on the needs of clematis, see page 41, and roses, page 46). You can boost the growth of annual vines by feeding them twice during the growing season -- once when they are about a foot tall and again when they begin to bud. In contrast, container-grown vines must be fertilized regularly.

Whatever the vine you're growing, be sure to use a balanced organic fertilizer, one in which the proportions of nitrogen, phosphorus, and potassium (the N-P-K numbers on the label) are equal. Avoid high-nitrogen fertilizers, which will produce lush foliage at the ex-pense of flowers.

Water: While vines need good drain-age—an important benefit of adding organic matter to the soil—most also require lots of moisture to support the heavy growth they make each year. Once climbers are well established, how-ever, they rarely need watering unless they are growing in an exceptionally hot, windy location, or in sandy soil in a region that re-ceives little rainfall. Wilting is an obvious sign that your vine needs to be watered—and that the soil in which it's growing needs more organic matter. Mulching will help retain moisture around the roots, as well as add nutrients to the soil.

Pruning: Many vines need selective pruning to keep them healthy and attractive -- and in bounds! Begin the process when plants are small by pinching off stem tips to encourage branching. Always remove damaged, diseased, weak, and dead stems. It is also good to thin dense-growing or tangled vines: Allowing more air and sun to reach the plant discourages pests and disease.

Annual climbers need little cutting back, except for shaping, but gardeners often prune perennial species each year to encourage flowering and to keep them under control (for the special needs of clematis, see page 42, and roses, page 50). Perennial vines should be pruned on the same schedule as flowering shrubs:

• Climbers that bloom in spring on old wood (the buds are formed the previous summer), such as Akebia quinata and jasmines, should be pruned within a week or two after they blossom.
• Silver lace vine and others that bloom in late summer or fall on new growth should be pruned in late winter or early spring, before the flower buds form.
• Perennial climbers that die back completely—in contrast to just losing their leaves—in autumn should be cut off a few inches above the soil line and the dead growth removed.

Perennial vines that have gotten totally out of hand can be pruned severely. Some species, including coral vine, Dutchman's pipe, most honeysuckles, and black-eyed Susan vine, will tolerate being cut to the ground. Others will stand up better to being pruned in stages, over three or four years. Remove a portion of the vine's oldest stems each year, cutting them back to a foot above the ground. Rejuvenation pruning is best done is spring, at the same time new growth begins.

Pests & Diseases: Most vines are not bothered by pests and diseases. Rather than treat a problem, avoid trouble by keeping climbers healthy. Give plants the amount of light they prefer, don't crowd them, and don't over-fertilize. Keep the planting area clean: Pull weeds and remove debris. Don't prune when foliage is wet; use clean shears, loppers, and saws. Immediately remove any leaves, stems, and flowers that appear to be diseased. Encourage beneficial wildlife—such as lady bird beetles and birds—to inhabit your garden.

When problems do occur, begin with the least toxic solution, such as hand-picking pests like Japanese beetles, hosing the vine with a sharp water spray, or treating with a dormant oil. Reserve botanical pesticides for the most serious problems, remembering that although these remedies are organic, they are poisons. (For specific problems and remedies, see "Clematis: The Queen of Vines," "Climbing Roses," and the individual entries in the "Encyclopedia of Flowering Vines.")

Protection: Gardeners in cold regions should protect their marginally hardy vines by mulching their bases. Both soil (bring it in—don't dig around the vine) and organic matter, such as compost, are effective; apply the mulch once the ground begins to freeze. To provide even more protection, wrap the vine's topgrowth with burlap. In hot areas, it may be necessary to provide vines with afternoon shade. A few vines are tolerant of salt air—bougainvillea is one—but most are not. Barriers are rarely successful, so coastal gardeners are better off planting climbers that will succeed in oceanside settings.