Wednesday, July 22, 2009

Jeepers, Creepers! Virginia Creeper and Boston Ivy

Parthenocissus is a genus of woody, creeping plants that, depending upon the species, are native to parts of Asia and of North America. The name comes from the Greek meaning "virgin ivy." Parthenocissus belongs to the grape family.

The plants may grow as ground covers, but will climb if they meet an obstacle. As they ascend, they attach themselves to the surface by small adhesive disks. Mature height may be 40' or more.

The two most common species in cultivation include Virginia Creeper (Parthenocissus quinquefolia) and Boston Ivy (Parthenoscissus tricuspidata).

Virginia Creeper, also known as Woodbine, is native to many parts of the U.S. and Canada. Each leaf is composed of five dark green leaflets. It is a vigorous climber and will cover whatever it grows upon. If allowed to grow over shrubs, its dense foliage can rob the lower plants of sunlight and weaken them. Fall brings bright colors of yellow, orange, red or burgundy. The depth of fall color seems to depend upon available sunlight. Virginia Creeper is widely used as an ornamental ground cover, but its fall color and ability to cover walls, trellises and pergolas makes it popular as well.

Virginia Creeper is cold hardy in USDA climate zones 3 through 9. It prefers average, well-drained soil with pH ranging from 6.1 to 7.8, but is tolerant of poor soils. It will grow in partial shade to full sun, is heat and drought-tolerant. Pests are limited to a few that nibble the leaves. It is disease-resistant. Birds love the fruit, but the berries are toxic to mammals. The plants can cause allergic reactions in sensitive persons.

Boston Ivy, also known as Japanese Ivy or Woodbine, is native to east Japan, Korea and eastern China. Each leaf is composed of three lobes. It is also a vigorous climber. Like Virginia Creeper, fall brings bright colors of yellow, orange, red or burgundy. It is also widely used as an ornamental ground cover, but is used to cover walls, trellises and pergolas. Because it has been very popular in Boston, it bears the name of that city.

Boston Ivy is cold-hardy in USDA climate zones 4 through 8. The foliage colors best in full sun, but it will tolerate partial shade. Plant in well-drained soil with average to poor fertility.

Prepare the planting bed for Parthenocissus by cultivating at least 6" deep, removing all traces of weeds. Compacted soil should be cultivated to 12" deep. Add enough soil to raise the bed at least 4" above the surrounding ground level. This will help to promote good drainage. Composted manure may be incorporated into the soil. Fertilizer may be used. If you choose to do so, incorporate 5-10-15 fertilizer at a rate of no more 2 lbs. per 100 square feet into the top 4" to 6" of soil. Avoid synthetic fertilizers contacting any part of your plants.

Plant Parthenocissus 12" to 36" apart. Dig planting holes into the cultivated soil a little less deep than the depth of the growing container. If you are planting bare root vines, the roots should be spread out in the hole. Do not plant them any deeper than they grew previously. You should be able to see a difference in the plant tissue at the previous soil line. Place the plants into the holes and back-fill, watering as you go. Press soil around the roots. If you are planting container grown stock, do not cover the root balls with soil. The tops should be slightly exposed. Add a top-dressing of mulch around the plants, not on top of them, about 2" deep.

If the plant is stressed during planting, it will usually drop its leaves as a protective measure. While it is unsightly and may be worrisome, maintaining proper soil moisture will encourage new leaves to sprout.

You might wonder whether it can be easily removed from walls, pergolas and such. It depends upon how you go about it. If you just start pulling them off a painted surface, the adhesive pads will probably pull off paint, especially if the paint is flaking. Because they do not attach themselves by means of penetrating roots, they will not damage brick or stone by pulling. The best way I've found to remove them is to sever their vines near the base, or spray foliage within reach with glyphosate herbicide. When the plants die and dry, the vines can be removed more easily.

Both popular species of Parthenocissus cover ground and buildings, and do it well. The fall colors are fantastic, and the plants are basically trouble-free.

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