The genus Hedera, commonly referred to as ivy, has over 450 varieties according to the American Ivy Society. English ivy, Hedera helix, is the best known and was used extensively as a ground cover because of its attractive evergreen foliage and ability to climb brick or stone walls and fences. Ivies are pest-resistant and water-conservative. They grow well in a wide range of light and soil conditions and can become invasive if allowed to seed.
Hedera helix 'Ritterkreuz'
Selected as the 2010 Ivy of the Year by the AIS, Hedera helix Ritterkreuz's leaf shape is reminiscent of a Maltese cross hence its name meaning 'knight's cross.' This variety originated at the Neuburg Monastery nursery in Heidelberg, Germany, and was registered by Brother Ingobert Heieck in 1981. Ritterkreuz is mid-green with lighter veins when grown indoors; when planted outside, the color becomes dark green with a reddish cast in winter. Ritterkreuz does well as a houseplant and can be used in all types of topiary. It is winter hardy to -10 F. Ritterkreuz is not particularly fast growing.
Hedera helix 'Eva'
The AIS Ivy of the Year for 2009, Hedera helix 'Eva' was discovered in the early 1960s by Tage Melin of Hjallese, Denmark. Eva's variegated cream-to-white margin with a green-gray center makes it a good houseplant or topiary choice. Grow in full sun for the best foliage color. If planted in partial shade, the variegation may fade to a pale green; cool temperatures cause the foliage to take on a pinkish hue. Eva is winter hardy to -10 F.
Hedera helix 'Gold Child'
Hedera helix Gold Child was The AIS 2008 Ivy of the Year. First introduced in 1971 by Thomas Rochford from the House of Rochford in England, Gold Child received the Royal Horticultural Society's Award of Merit. Gold Child's variegated foliage has a bright-gold margin with a green to green-gray center. Foliage brightness is temperature dependent with foliage turning an intense gold in cooler temperatures then fading to butter yellow in warmer weather. If grown in the shade the color is less intense but the variegation is still prominent. Gold Child makes a good houseplant with long runners and is hardy to -20 F outdoors.
Hedera helix 'Shamrock'
The AIS 2007 choice for Ivy of the Year, Hedera helix Shamrock is a miniature bird's-foot ivy discovered in the early 1950s by Louis Hahn & Son Nursery in Pittsburgh, Pennsylvania. Shamrock is dark green with lighter veins and has three lobed leaves that resemble its namesake plant. Easy to grow in all light conditions and hardy to -20 F outdoors, Shamrock makes a good houseplant or topiary plant and grows well when planted outdoors.