Rodale's Ultimate Encyclopedia of Organic Gardening: The Indispensable Green Resource for Every Gardener
Editors: Fern Marshall Bradley, Barbara Ellis, Ellen Phillips
Paperback, 720 pages
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Ivy: Evergreen woody vines.
Description: Hedera helix, English ivy, is a vigorous evergreen vine with shiny 3- to 5-lobed leaves, 2 to 5 inches long. Although this vine is very well known, it should be planted with caution because it is a nonnative species that can become invasive in some regions. It easily spreads beyond gardens, where it blankets woodlands, outcompetes native wild flowers, and overwhelms trees. Plants spread by stems that twine and attach by rootlets. Zones 5–9; some cultivars are hardy to Zone 4.
H. canariensis, Algerian or Canary ivy, is similar to English ivy but more tolerant of heat. Zones 9–10 and the milder parts of Zone 8. H. colchica, Persian ivy, displays large leaves and coarse growth. Zones 6–9. Both of these species also show invasive potential in warmer regions.
How to grow: If you choose to grow ivies, plant them on sites where buildings, paved walkways, or other structures will keep them contained. Start with rooted cuttings or transplants in spring or fall. Plants prefer moist, humus-rich, well-drained soils and tolerate acid or alkaline conditions. Give them partial or dense shade — they won't tolerate full sun or hot sites. Ivies are relatively free of pest and disease problems. Prune regularly to keep them from spreading.
Landscape uses: Ivies serve well as groundcovers or climbing vines and are valued as low maintenance plants. They are especially useful in dense shade, where little else will grow. Site them very carefully and keep them away from sites where they can spread to wooded areas. The vines have holdfasts on aerial rootlets that allow them to cling to brick and masonry walls. However, be aware that rootlets can work their way into cracks in the wall and eventually dislodge pieces of brick or stone. Use small-leaved or variegated ivies to grow over topiary forms, plant them in containers or hanging baskets, or grow them as houseplants.
Reprinted from Rodale's Ultimate Encyclopedia of Organic Gardening © 2009 by Rodale Inc. Permission granted by Rodale Inc., Emmaus, PA 18098.