BY LAUREN SPRINGER OGDEN / Fort Collins, Colorado, USDA Zone 5
PLACES TO GO
Denver Botanic Gardens
Even in the firm grip of a Colorado winter, there’s still much to see at the Denver Botanic Gardens. Evergreen foliage of dwarf conifers, succulents, subshrubs, and mat-forming perennials grace the stonework of the Rock Alpine Garden. Woody lilies are well represented there, yet take on a higher profile in Yuccarama, a bold planting at the building’s entrance; in Dryland Mesa, a naturalistic outcrop artfully designed with solely western and southwestern native plants; and in the Watersmart Garden, where drought-tolerant plants of cosmopolitan provenance intermingle with the strong sculptural forms of these plants.
The woody lilies, also known as fiber plants, include yuccas, agaves, nolinas, hesper-aloes, and sotols. Gardeners either love or despise them. Be that as it may, these plants offer an architectural evergreen presence that anchors the formless, fine-textured floral fare that fills many a dryland garden, giving the much-needed oomph most of these gardens lack. They also hark from some of the most beautiful natural landscapes in the United States and Mexico, so for those of us who wish to reflect the wild in our gardens, the woody lilies connect us directly with that beauty.
But what about the colder parts of the West? Most of the following have survived –15°F in my garden. First, no more sneering at our lovely native soapweed, Yucca glauca. Come late spring and early summer, creamy flower spikes glow like waxy tapers on hills, prairies, and mesas from northern Texas and Oklahoma well into Canada. Some populations have maroon brushstrokes on the outer petals. Banana yucca (Y. baccata; pictured) has broad, concave foliage ranging from olive green to powder blue with curled filaments along the margins. Southeastern, moisture-tolerant natives Y. filamentosa and Y. flaccida offer variegated forms that are popular across much of the country. For long bloom, Hesperaloe parviflora, the red yucca, is unsurpassed. Coral, red, or soft yellow tubular blossoms attract hummingbirds for months. The rolled, narrow, dark green foliage turns plum in winter.
Dollhouse yucca, Y. harrimaniae, is ideal for smaller-scale plantings with its pert, filamented, 6- to 12-inch rosettes. Other compact plants include the sensual blue-gray foliage rosettes of Agave parryi, and A. utahensis, with narrower green foliage. I am also enamored of shade-tolerant Texan natives Yucca pallida and Y. rupicola. The former is pale blue and tolerates heavy, moist soils. The latter has deep olive-green foliage with a bright yellow margin, and leaves that undulate in a most seductive way.
For sun or light shade, beargrasses offer a graceful, arching green effect. Nolina microcarpa is the coarsest; smaller N. lindheimeriana and N. texana have narrower foliage. The dramatic but wickedly toothed sotols (Dasylirion spp.) have been the touchiest for me, but a high-elevation form of blue D. wheeleri, as well as green D. leiophyllum and D. texanum, are alive after –10°F, with varying amounts of foliage burn, the latter with the least. As with all the woody lilies, the drier they are grown, the hardier they are.
Successful trunked yuccas include high-elevation forms of the elegant Y. elata and the famous bristle-topped Joshua tree of the Mojave desert, Y. brevifolia, as well as stiff blue, slow-growing Y. schottii and finer-textured, gold-edged, green or blue Y. thompsoniana. Similar but with more pliable foliage is blue Y. rostrata, whose leaves wave and rustle in the wind.
For living garden sculpture, there’s nothing like Agave neomexicana, A. scabra, and A. havardiana. Their two-foot rosettes vary from gray green to blue gray. Agave scabra is the least hardy, but has tolerated –10°F. Agave havardiana is my favorite: a curvy, symmetrical, wide-leaved number. It impales me regularly, but as I lick the blood off my hand I have nothing but respect for the power of this ferociously beautiful plant. H
Agaves, Yuccas, and Related Plants
by Mary and Gary Irish (Timber Press, 2000; $34.95)
This is a must-read for lovers of these spectacular plants. Whether choosing species to grow in the ground or adding to an ever-expanding collection of containerized specimens, the reader can find a wealth of botanical, cultural, and aesthetic knowledge, presented in a well-organized, friendly, inviting manner. The photographs are botanical equivalents to the Sports Illustrated swimsuit issue—never did plants look so shapely. (For more by Mary Irish, see “Agaves,” November/December 2003.)