Hostas: Ultimate Shade Perennials
For three years in a row, hostas have been the best-selling perennial in North America, and they aren't likely to relinquish their number-one status any time soon. The main reason for their rapid rise to the top is that many American gardens are getting shadier, as street and yard trees mature. And there is no better way to put bright colors in a shady spot season after season than by planting hostas. The bold leaves come in a striking range of both solid hues and bicolors ("variegated" is the preferred term). In summer come the tall spikes of white or lavender flowers, but with hostas it's the season-long show of leaves that counts most.
It takes more than good looks, however, to make a plant a world-class winner. Very few perennials are carefree plants, but hostas come close. They never need dividing. Once established, they shade the ground so thoroughly that they reliably crowd out most weeds. Their only problem is slugs, a pest that can usually be controlled with diligent cleanup. Hostas are not fussy about soils and many cultivars even do quite well with considerable sun. It's no wonder that gardeners are planting them in record numbers.
Early to midsummer is the ideal time to shop for hostas. In midsummer, container-grown plants in local nurseries will be in full leaf so you can get a good idea of what the different varieties will look like. Liberated from the pot, however, and growing in good garden soils, the leaves will get up to twice as large.
Hosta leaves come in a broad range of solid colors, from blue-gray to deep green to light green or gold. Blue hostas often have a soft, waxy bloom, especially early in the season. Some green leaves are very shiny. Variegation can be white, cream or yellow and can occur on the edges of the leaves, in the centers of others or else be streaked throughout the leaf. The most common leaf shape is heartlike, but some cultivars have narrow, straplike leaves. The largest hostas are three to four feet tall; the smallest are under eight inches. Mix all these factors together and you get an idea of why plant breeders are having such fun with this group of plants.
Today, nurseries grow and sell selections from about 10 different species and their hybrids. There are about 400 cultivars in the trade and the number is growing rapidly. You can plant container-grown hostas from early spring to fall. If you want to buy hostas by mail, you should order right away. Some mail-order nurseries will ship your hostas within weeks; others will wait until autumn. Plants may be shipped in containers or bare root. Either way will be fine for your garden; hostas are very tough plants. Spring planting is fine, too.
Typically, the plant you buy is a one- or two-eye division. The eye is a piece of a stubby underground stem or "rhizome" containing a single squat, conical bud from which the leaves arise. The many roots that grow from the rhizome are about as thick as heavy twine, something like the roots of daylilies. New rhizomes form slowly, and a clump may take four or five seasons to begin looking its best.
When spacing hostas in the garden, a good rule of thumb is that the plants will spread about 50 percent wider than they are tall: A 24-inch hosta will spread to cover a circle about 36 inches across when the plant is mature. That can be in four to six years, depending on the vigor of the variety. Experts advise against planting hostas closer in an attempt to get a full effect sooner. Instead, fill in with daffodils, Virginia bluebells or annuals. Established hosta plantings have been in place for 30 years and longer with no need for dividing.
Where Hostas Grow
Hostas are among the most adaptable perennials. They do well in USDA hardiness zone 3 (-40? F minimum) southward as far as zone 9 (20? F minimum). Hostas need a period of cold weather, at the onset of which they turn a pleasing yellow and then go dormant. Insufficient winter chill and dry air, such as in western deserts, are the chief limiting factors.
Some hostas are native to woodlands and others grow in moist meadows where tall grasses provide some shade. In the garden, one-third shade is ideal. If soil moisture is ample, most hostas can take direct sun, especially in cooler climates and at the northern limit of their range. Gold varieties must have some direct sun for their full color to develop; in shade they become chartreuse. When hostas get too much sun or not enough water, the leaf edges become papery and brown. At the southern edge of their range, more shade is beneficial. Blue varieties develop best color in shade. When you grow any hostas in the shade of large trees, fertilize them with a two-inch mulch of compost or leaf mold each year to help the plants compete with the tree roots.
To learn more about hostas, join the American Hosta Society at 7802 N.E. Sixty-third St., Vancouver, WA 98662 for a $19 annual membership fee. At 133 pages, The Hosta Book by Paul Aden (Timber Press, Portland, Oregon, 1990; $17.95) is a thorough reference. In addition to local nurseries, hostas are available from several mail-order nurseries.
Classified by height, hostas fall into four groups: small (8 and less), medium small (up to 12), medium large (up to 24) and large (25 and up). Hostas of any size can make a weed-proof ground cover if grown thickly enough, but in most situations, plants from the two taller groups serve best, hence their popularity. Varieties from the two smaller groups are best as edging, in rock gardens or among mixed plantings of other smaller perennials. The best-selling hostas have variegated leaves on medium- to large-sized plants, and the nine pictured here reflect this preference.
Jack Ruttle is a former senior editor at National Gardening.
Photography by National Gardening Association