Fortnight Lily is a rhizomatous evergreen perennial producing clumps of long, upright narrow leaves that reach 2 to 4 feet tall. The flowers rise above the foliage and look like small Japanese irises. Fortnight Lily produces many flowers from spring to late summer, with a fortnight (two weeks) of rest between each flowering period, thus the common name. It freely self-seeds, but you can prune the blossoms to reduce seed production.This plant looks amazing as a groundcover, in a potted container, or in a rock or woodland garden. It has grass-like features and dainty flowers that allow it to stand its own in any garden. Plus, it is low maintenance which can be a plus for any busy gardener. There are five species of Dietes , four from Africa and one species from Lord Howe Island east of Australia. The genus name comes from dis meaning double. Best flowering occurs in full sun, but the plant does best with some part light afternoon shade. Fortnight Lily tolerates drought and some soil dryness, but you should provide regular moisture. The plant is winter hardy in USDA zones 9 through 11, but can be injured when temperatures drop below 50 degrees F. (10 degrees C). In cooler climates it can be grown as an annual or you can dig up the rhizomes and store them indoors for winter. Potted plants can be brought indoors. In the garden, the plants do best in moist, moderately fertile, well-drained soils in full sun to part shade. When planting, place the woody rhizomes 12 inches apart, 1 per square foot, and bury to a depth of 1 inch (2.5 cm). Diseases, Insect Pests, and Other Plant Problems: Nematodes are the main pest problem. Scales can cover the foliage and cause a severe problem.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Fills a similar nicheBuddleja Lo & Behold® 'Blue Chip Jr.'Phlox INTENSIA® GroupStokesia laevis
Full plant profile
Growing Conditions
Plant type
Bulb; Ground Cover
Life cycle
Bulb
USDA zones
9a, 9b, 10a, 10b, 11a, 11b
Light
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand
Soil pH
Neutral (6.0-8.0)
Soil drainage
Good Drainage
Available space
12 inches-3 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 4 ft. 0 in. | Width: 1 ft. 0 in. - 1 ft. 0 in.
Growth rate
Medium
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Arching; Erect
Texture
Medium
Foliage
Broadleaf Evergreen
Leaf color
Green
Leaf type
Simple
Leaf shape
Linear
Leaf margin
Entire
Leaf value
Long-lasting
Hairs present
No
Leaf detail
Narrow, sword-shaped, basal, evergreen iris-like leaves in fan-shaped clumps.
Flower color
Blue; Gold/Yellow; Purple/Lavender; White
Flower value
Long Bloom Season; Showy
Flower form
Head
Flower shape
Star
Flower size
1-3 inches
Flower detail
Three inch wide flowers are white with yellow and blue markings resembling a small Japanese Iris. Flowers appear on branched stalks from spring to fall and intermittently throughout winter. Flowers last one day, but are quickly replaced. Each flower stalk carries a large supply of buds. Flowering occurs in bloom bursts that often occur at 2 week intervals.
Bloom time
Fall; Spring; Summer
Fruit color
Green
Fruit type
Capsule
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
Half to 1 inch obovoid capsule with several seeds.
Wildlife & Ecology
Native status
Non-native
Origin
Ethiopia to South Africa
Distribution
Hawaii, Australia, parts of the Caribbean and Mexico.
Food & Medicine
Fruit type
Capsule
Uses (ethnobotany)
Used in traditional medicine to treat cold, flu, headache, toothache, malaria, bruise and various infections.