Desert Delights: Dryland Plants

Credit: Andrew Cowen, Jonathan Buckley

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Add an exotic touch to your containers with spiky and succulent desert dwellers, right here in BC

For many years, the central gathering area at VanDusen Botanical Garden featured a “dry bed” collection of spiky and succulent desert dwellers. Each fall the plants were dug, potted and returned to the large service greenhouse to be protected from winter weather, especially rain. Once the danger of frost had passed in spring, the collection returned to the triangular bed that framed it. I once saw a group of Mexican visitors greet this bed with “Aha! Little Mexico!” upon recognizing some compatriots, but the collection actually included species from many parts of the world. The adaptations they have made to survive in drier climes account for their similar appearance – and their appeal. For home gardeners, the only practical way to grow these plants is in containers. In a handsome pot, they create dramatic seasonal accents, especially in a group on a sunny patio. Plus, the portability of pots allows you to move them into frost-free or dry places in winter – essential for winter survival.

Agave americana ‘Marginata’ Echeveria Agave attenuata Aloe aristata

Bold, angular silhouettes are provided by members of the agave family, which include Agave, Dracaena and Yucca. One of the largest species is the century plant or American aloe, Agave americana, which is native to Mexico. Its lance-shaped, spine-tipped, spiny-margined leaves reach to 1.8 metres long, making it a beast to dig each fall. Three striking cultivars of this plant are ‘Variegata,’ ‘Marginata’ (with pale-margined leaves that often become white with age) and ‘Mediopicta’ (which has a broad, pale-yellow band along each leaf). The latter stays the smallest, making it more useful for taking into a greenhouse in winter. A variegated agave in a square terra-cotta pot makes a playful combination. Much gentler is the beautiful soft-tip agave, Agave attenuata, also from Mexico. Its blue-grey leaves are wider in the middle and taper to a soft spine. Plants eventually form a tall slender trunk of dark grey, marked with triangular leaf scars. At the base of the trunk, offsets emerge that can be removed and potted separately. This makes it ideal for containers, as young plants can replace older ones that have become too large. Due to the recent mild winters on the south coast, many otherwise tender plants have survived outdoors for several years. Among them is the agave family member commonly sold as a centrepiece for container plantings, nicknamed “spike” by some gardeners. Cordyline australis, or New Zealand cabbage tree, gains height as it matures. This summer I was surprised to see these older plants in bloom and enjoyed their fragrance. A much smaller succulent, Aloe aristata (torch plant or lace aloe) is easily managed as a houseplant, in a sunny window. One of its prettiest features is the small white spots and marginal spines on its dark-green leaves. Its showy orange-red flower clusters (the “torch”) appear in late summer. It is native to the mountains of South Africa, where winters are dry but can reach –9°C. The trick, if you want to try it outdoors in winter, is to keep it completely dry. Tuck it next to a building or under an overhang where it won’t get any rain. During the growing season, however, keep it well watered. The stonecrop family is entirely succulent, with such familiar garden perennials as Sedum and Sempervivum. Look to two tender genera, Echeveria and Aeonium, for dramatic ornamentals. Echeveria, sometimes erroneously called hens ’n’ chicks (which is Sempervivum), includes about 150 species, and plant breeders have gone wild creating new hybrids. E. elegans (Mexican gem) is a commonly seen species, with neat rosettes of spoon-shaped, silvery-blue leaves and one-sided clusters of yellow-tipped pink flowers held on 25-centimetre stalks. E. pulvinata (plush plant) has leaves covered with white hairs. In recent years, hybrids have appeared that resemble sea creatures rather than plants! Some have large, flattened, wavy leaves that never fail to grab attention. Although most references state that these are only hardy to 7°C, they do tolerate some frosts in their native Mexico. If you plan to leave them out in winter, tuck them in close to a building where they will be sheltered from rain. If the weather turns cold suddenly, you can bring them into a cool garage or shed to wait it out. Alternatively, Echeveria can be grown indoors in a sunny window. Aeonium differs from Echeveria in developing a stem below the rosette of leaves. A popular cultivar is A. arborescens ‘Zwartkop,’ which has dark, almost black leaves, making a striking addition to any containerized succulent collection. The species is native to Morocco and plants should be grown indoors in winter. I hope this gives you a taste for some of the spiky or succulent plants that have found ways to adapt to the drier parts of our planet. Try a few in containers, expanding your garden zone to include some exotic plants from warmer locales. You’ll be hooked! The following plants are hardy to the temperature indicated:

• Aeonium arborescens ‘Zwartkop’ 10°C
• Agave americana 5°C
• Agave attenuata 10°C
• Aloe aristata – 9°C if dry, but reliably hardy to 10°C
• Echeveria elegans 7°C, hardier if soil remains dry during winter
• Echeveria pulvinata 7°C, hardier if soil remains dry during winter

With more than 30 years experience in horticulture in B.C. – in wholesale, retail and at VanDusen Botanical Garden for a decade – Carolyn Jones brings a wealth of knowledge and expertise to GardenWise and www.gardenwiseonline.ca as staff horticulturist.