Dietes grandiflora
large fortnight lily
Overview
Dietes grandiflora is an evergreen rhizomatous perennial forming upright fans of strap-shaped leaves 24-40 inches (60-100 cm) tall and spreading 24-36 inches (60-90 cm) wide into clumps. The dark green leaves are stiff, sword-shaped, and arranged in flat fans from a creeping rhizome. Iris-like flowers about 3-4 inches (8-10 cm) across open on tall, branched stems; each flower is white with three yellow blotches and three violet inner segments marked with brown. Individual flowers last 1-3 days, but the plant produces flushes of bloom every few weeks through spring and summer, a habit reflected in the common name. The flower stems persist and can rebloom in later seasons. Seed capsules grow heavy enough to bend the stems to the ground, where seeds germinate to form new plants. Growth is moderate, with clumps expanding steadily and tolerating drought, poor soils, and neglect once established. The plant can self-seed widely and is regarded as a weed in some warm regions outside its native range.
Native Range
Native to eastern South Africa, from the Eastern Cape through KwaZulu-Natal, where it grows on forest margins, grassland, and stream banks. It is widely planted elsewhere and has naturalised in parts of Australia and other warm regions.Suggested Uses
Planted in borders, mass plantings, and low-water and coastal gardens, spaced 24-36 inches (60-90 cm) apart. Used along driveways, in median strips, and in containers of at least 5 gallons (19 L). Self-seeding can spread the plant into bushland, so it is kept away from natural areas in regions where it has naturalised.How to Identify
Appearance
Size & Dimensions
Height2' - 3'4"
Width/Spread2' - 3'
Reaches mature size in approximately 2 years
Bloom Information
Detailed Descriptions
Flower Description
White with yellow and violet markingsFoliage Description
Dark greenGrowing Conditions
Sun Requirements
Requires 5-9 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grows in full sun to part shade in most soils, including poor and clay soils, with low to moderate water. Established clumps tolerate extended drought, though flowering is heavier with regular moisture. The plant withstands light frost, with foliage damaged below about 25°F (-4°C). Old flowering stems are left in place to rebloom rather than cut off. Crowded clumps are divided in spring or autumn. Self-sown seedlings appear around established plants and can spread into surrounding areas.Pruning
Old flowering stems are left in place, as they rebloom in later flushes and seasons; removing them stops further flowering from that stem. Spent leaves are trimmed at the base as they brown. Crowded clumps are divided in spring or autumn.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
springfall
Container Growing
✓ Suitable for container growing
Minimum container size: 5 gallons