Culture
Winter hardy to USDA Zones 7-11 (possibly 6-11). Bulbs are easily grown in moist,
organically rich, fertile soils in full sun to part shade. Large mature bulbs typically tolerate somewhat drier soil conditions than small bulbs. Best growth occurs in full sun, but this plant appreciates some light shade during the heat of the day in hot summer climates.
Winter temperatures often determine the best planting strategy: (A) Where winter hardy, plant bulbs in a moist soil in spring for year round outdoor growth. Plants will often spread over time to form large colonies. (B) Where marginally winter hardy, plant bulbs in a protected location (e.g., southern exposure) in moist soils in spring for year round outdoor growth and mulch with evergreen boughs, hay or dead leaves over winter. (C) Where not winter hardy, plants are usually grown in containers which are planted outdoors in spring after last spring frost date and then dug up and brought indoors prior to the first fall frost date for overwintering in a cool sun room. Plant bulbs in pots or containers that are at least two inches larger in diameter than the bulbs. Bulbs like to be pot-bound. Set bulb in the pot with the neck exposed. Keep soils moist to wet and fertilize regularly during the growing season. Bring containers inside in fall before first frost for overwintering in a frost-free location. Return containers to the garden after last spring frost date.
Although plants can technically be grown directly in the ground (as opposed to in pots) in St. Louis by planting the bulbs in late spring and lifting the bulbs in fall in somewhat the same manner as for dahlias, this is not always considered good practice because crinum roots do not like to be disturbed and once disturbed plants may not bloom for another 2-3 years. It should be noted that some gardeners have been able to successfully grow this crinum hybrid year round in the ground as far north as Zone 6 with a good winter mulch and protected location, however the risk of loss is ever present.
Noteworthy Characteristics
Plants in the genus Crinum are bulbous perennials in the Amaryllis family which produce showy, fragrant funnel-shaped flowers in umbels atop naked scapes rising above a tuft of narrow strap-shaped basal leaves.
Crinum x powellii, commonly called swamp lily or Cape lily, is a hybrid of garden origin resulting from a cross between two South African crinums, namely, C. bulbispermum (orange river lily) and C. moorei (natal lily). This hybrid typically produces a clump of narrow, strap-shaped green leaves to 3-4’ long and to 2-3” wide near the base from which rises a naked flower scape to 4-5’ tall which is topped with umbels of 8-10 showy, fragrant, trumpet-shaped, pink flowers (each to 4” diameter) which bloom in succession from late summer to early autumn. Leaves are evergreen in frost free winter climates, but will die back in freezing temperatures. Long necked bulbs are large (to as much as 7” in diameter) with tapered necks.
All parts of this hybrid lily are toxic if ingested. Direct contact with plant sap may irritate areas of skin.
Genus name comes from the Greek word krinon meaning lily.
Hybrid name honors C. B. Powell (1830-1904), Irish/English businessman and avid gardener who developed and introduced this bulb around 1858.
Problems
No serious insect or disease problems. Slugs and snails are occasional visitors.
Uses
Borders. Foundation areas. Circular drive centers.