When it comes to gardening in the Southwest, selecting the right flower bulbs is crucial to creating a vibrant landscape. The region’s arid climate and unique soil makeup require plants that can thrive in hot, dry conditions. But the best options still provide those familiar bursts of color that most gardeners are accustomed to seeing when the word “bulb” is mentioned. The following are some of my favorite ornamental flowering bulbs for the Southwest, with varieties that not only survive our regional conditions, but bring unsurpassed beauty to even the most challenging spots.
Knysna Lily
(Cyrtanthus obliquus)
Zones: 9b–10
Conditions: Full sun to partial shade; well-drained soil
The genus Cyrtanthus is a colorful group with wide variation in habit and flower form. Knysna lily, the largest one, might be named the queen of the bunch, if I had a say in it. A plant from South Africa’s southeastern grasslands, its onion-like bulbs sit partially exposed above ground, while white fleshy roots anchor it securely below. Three to five thick evergreen leaves stand upright with a slight twist, to about 14 inches. Once mature, the flower spikes emerge in mid-spring, rising above the leaves and crowned with five to twelve pendulous orange flowers, shading yellow and green at the tips. Tolerant of heat and drought, Knysna lily has survived best for me in the Sonoran Desert when provided dappled sun through midday. It does well when kept on the drier side through the cool winter months, although it does not mind summer rain if the drainage is good. I grow my Knysna lilies in the ground in Tucson, where they emerge through a soft bed of silver dichondra (Dichondra cv., Zones 10–11). I have only seen occasional minimal frost damage to some leaves in their sheltered location, but protection from harder freezes would be advised. This is a stunning specimen when grown in containers as well.
Fire Lily
(Cyrtanthus sanguineus)
Zones: 9b–10
Conditions: Full sun to partial shade; well-drained soil (drier in winter)
A second favorite from the same genus Cyrtanthus, this variety also hails from eastern South Africa. Several subspecies exist with variable flower colors from hot red to pink. Fire lily forms small colonies over time, its bulbs at—or partially buried below—the soil surface. The strap-shaped leaves are upright to lax, reaching about 12 inches long. Clustered blooms appear reliably in midsummer, rising slightly above the leaves, with each fiery red-orange flower lasting about a week. It’s a brilliant and welcoming display when planted among rocks with minimal competition. Fire lily is sensitive to hard frost if not sheltered but also a superb container plant that can be protected more easily.
Fan-Leaved Boophone
(Boophone disticha)
Zones: 9b–10
Conditions: Full sun to partial shade; well-drained soil
Many of the other common names for this plant reflect the fact that the bulbs are poisonous, such as “Cape poison bulb.” Whatever you choose to call it, boophone has a wide range across South Africa, spanning both the summer rainfall and the winter rainfall regions, and the gradations in between. Always keep it on the drier side, and when the leaves start to wither, you’ll know the plant wants to go dormant. Withhold water for at least a month once leaves have fully faded. Then growth will resume, and you will be rewarded with an otherworldly fan of wavy blue-green leaves about 10 to 12 inches tall. These emerge from the papery ring of old leaf bases where the neck of the bulb emerges 2 inches or more from the ground. Bulbs can reach 6 or more inches in diameter. Light frost will not harm them during their leafless dormant phase, but protection is recommended at other times. Boophone makes a striking container specimen, especially when a large mature bulb surprises you with its volleyball-sized head of pink flowers!
Splendid Sword Lily
(Gladiolus splendens)
Zones: 8b–10
Conditions: Full sun to partial shade; well-drained soil (drier during dormant period)
This plant came to me by accident, after few dormant bulbs had apparently self-sown into another plant that was given to me. After watching the tall slender leaves appear spontaneously for a couple seasons, I was happy to finally see a flower spike emerging one early spring. By the time it had reached nearly 3 feet tall, I could see that it was indeed a member of the Gladiolus genus, but not the top heavy “funeral arrangement” type. With its slender habit and refined features, a quick search assured me of its identity. This bulb grows in rocky slopes and grasslands in the West Cape of South Africa, so it responds to winter rains with fresh foliage and tantalizingly slow flower spikes that produce two alternating rows of exotic scarlet flowers. Splendid sword lily is one of the first flowers each spring to get the attention of local hummingbirds in Tucson. Seeds are formed freely, and seedlings do appear to ensure future displays, but once summer heat arrives, the plants go dormant and disappear completely until the next winter rains.
 |
 |
Surprise Lilies
(Lycoris spp. and cvs.)
Zones: 4b–10
Conditions: Full sun to partial shade; well-drained soil
Commonly known as surprise lilies or spider lilies, Lycoris have a long history as garden plants. Many of the familiar red ones have been passed along for decades as heirloom plants. But today, there is a wealth of forms and flower colors to choose from. Hybrids abound, ranging from rose pink with blue tips, to gold, white, and salmon orange. Hardiness varies, and most older varieties were restricted to Zone 7 and above. Today’s hybrids are stretching that range, reportedly surviving zones as low as 4b, so choose your plants accordingly. What all surprise lilies have in common is a period of leaf growth (either in fall or spring), followed by dormancy in early to midsummer, followed by the emergence of flowers in late summer. The 1- to 2-foot flowering stems usually appear out of bare ground long after the leaves have faded, hence the “surprise” in the name. Best to mark their location in some way so as not to disturb them. They are tolerant of regular watering, but less is acceptable while dormant.
Cape Buttercup
(Sparaxis elegans)
Zones: 9–11
Conditions: Full sun; well-drained, clay loam soil
These small corms resemble those of common Crocus species, but their spring display is anything but common. Cape buttercup bulbs respond to winter rains as they would in their native West Cape of South Africa, producing a small fan of leaves just 6 inches tall over the winter. Spring flowers are typically a warm coral-tangerine color with occasional white or other iterations. Their centers are exquisitely patterned in black, yellow, and purple kaleidoscopic markings. These plants can bloom in their second year from seed. Bulb colonies will also expand on their own under good conditions. A dry summer rest is essential for these spring gems, so allow them to dry out well after flowering. Cape buttercup is also well suited to a container that can be ignored all summer, resuming water and sun through the winter months for a beautiful spring display.
Discuss this and any other gardening topic in our Southwest gardening forum.
Dan Johnson lives and gardens in Denver, Colorado, and in Tucson, Arizona. He is an associate director of horticulture for the Denver Botanic Gardens.
Photos: Dan Johnson