While it may be hard to have a passion for anything outside during the heat and humidity of late summer in Iowa, I think fondly of the colors in my landscape. As I look out of my air-conditioned window, I watch the curtain close on some of the summer blooming perennials and note that the beauty of fall blooming plants has not yet arrived. In this lull, we look to plants with colorful foliage to provide interest. While there are a number of colorful possibilities, one of my gardening passions is for reddish-purple foliage. Purple leafed plants are not limited by size. There are 60-foot trees and 6-inch herbaceous perennials, and everything in between.
Commonly grown woody plants with purple foliage include 'Crimson King' Norway Maple, 'Schubert' Cherry, Sandcherry, and Barberry. Common, however, is not always a negative. 'Crimson King' or 'Royal Red' Norway Maples (Acer platanoides) are beautiful large shade trees with deep reddish-purple leaves that resist fading. Cold hardiness is not a problem in Iowa for these trees. However, sunscald and slow growth are common problems with the purple leafed Norway Maples. Trees can attain a height of 50 feet, but will take their time in their lofty pursuits. For best performance, plant young trees in fertile, moist, well-drained soils in full sun.
Other purple foliage plants are the 'Schubert' or 'Canada Red' Chokecherry (Prunus virginiana) and Sandcherry (Prunus x cistena). While the Chokecherry may grow 15 to 20 feet tall, the Sandcherry is about half that size. Both are often over-used in the landscape due to their fast growth, durability, and tolerance of poor sites. Their only site requirements are plenty of sun and a well-drained soil. Unfortunately, they are also short-lived landscape plants. One advantage the Sandcherry has over the Chokecherry is its ability to retain its dark reddish purple foliage throughout the plant for the entire growing season. The green new growth on Chokecherries gives the plant the appearance of a bad dye job at the salon with their purple roots showing up in spring.
Barberry (Berberis thunbergii var. atropurpurea) is another readily available shrub with purple foliage. Cultivars like 'Crimson Pygmy' and 'Rosy Glow' add color (and thorns) to the landscape. 'Crimson Pygmy' is a rounded, dwarf form reaching 2 to 3 feet tall, while 'Rosy Glow' is more upright at 5 feet. 'Rosy Glow' has pink-streaked new growth that contrasts with the darker purple areas of the leaves.
For a couple of uncommon and unusual purple woody plants, there are Smokebush (Continus coggygria), and a few Crabapples (Malus hybrids) varieties. Smokebush is a 10 to 15 foot multi-stemmed shrub with feathery, smoke-like flowers in summer. Cultivars like 'Royal Purple' and 'Velvet Cloak' command attention in and out of bloom. For northern Iowa, the cultivar 'Nordine' may be more reliably cold hardy. However, the foliage of 'Nordine' is more bronze-purple rather than the deep red-purple of the other cultivars. There are several varieties of Crabapples with purplish new growth, like 'Robinson', 'Prairiefire', and 'Purple Prince'. These vary in habit and range in mature height from 12 to 25 feet, but all are relatively disease resistant and provide attractive flowers in spring.
Purple Beech (Fagus sylvatica), Purple-leaf Japanese Maples (Acer palmatum), and 'Forest Pansy' Redbud (Cercis canadensis) complete the list of woody plants with purple foliage. All of these are exceptional, slow-growing trees in the landscape. They are more site-specific than the other woody plants mentioned, requiring a protected site in partial shade and moist, fertile soils that are well drained. They are also expensive and not reliably hardy for many parts of Iowa.
For something smaller in size, there are several herbaceous perennials with purple foliage. 'Palace Purple' Coral Bells (Heuchera hybrids) leads the pack for carpeting the understory of trees and lining sidewalks. There are several other purple foliage varieties of Coral Bells available on the market today and many more in the pipeline for garden centers in the future. 'Chocolate Ruffles', 'Pewter Veil', 'Amethyst Mist', and 'Plum Pudding' are just a few with variations of purple, silver, and undulating leaf edges available. These plants prefer partial shade and well-drained soils and range in heights from 6 to 20 inches.
Another common purple leafed perennial is 'Husker Red' Penstemon (Penstemon digitalis). The new growth is a distinct burgundy-red color on upright 2 to 3 feet tall plants. White flowers in late spring complement the foliage. The foliage fades to green as the season progresses.
'Chocolate' Joe-Pye Weed (Eupatorium), Burgundy-leafed Snakeroot (Cimicifuga ramosa), and 'Chameleon' Spurge (Euphorbia dulcis) may sound like strange plants for the landscape, but they are wonderful purple foliage perennials. 'Chocolate' Joe-Pye Weed and the burgundy snakeroot have white blooms in late summer and fall. Both the prefer partial shade and moist soils. 'Chocolate' Joe-Pye Weed grows 3 feet tall. 'Brunette', 'Atropurpurea', and 'Hillside Black Beauty' are three prized and expensive purple leafed cultivars of Snakeroot that reach 3 to 6 feet tall. 'Chameleon' Spurge is a rounded plant that reaches 12 to 18 inches tall and performs best in sun. It produces yellow-green flowers in spring.
The purple foliage plant list doesn't end with these plants. There are also many annual plants with purple foliage, like the Purple Fountain Grass and Purple Ruffles Basil. Plant a few of these colorful foliage plants in your yard and add a little passion to your landscape.
This article originally appeared in the August 10, 2001 issue, p. 100.
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