Dietes bicolor aka Fortnight Lily

Dietes bicolor is native to South Africa, specifically from the Southern Cape Province to Southern KwaZulu-Natal. It occurs naturally in the Bathurst region of Eastern Cape and is typically found near streams and in marshy places. The genus Dietes contains five species total, with four native to Africa and one to Lord Howe Island (between Australia and New Zealand). Molecular analysis suggests D. bicolor is the most primitive species in the genus.

Dietes bicolor thrives in temperatures between 50°F to 85°F (10°C to 29°C) but tolerates a wide range. The plant is frost-tolerant and can handle mild frosts, surviving temperatures down to 15-25°F (-9°C to -4°C). However, temperatures below 25°F will cause foliage and bloom damage. In colder climates, bring potted plants indoors or dig up rhizomes for winter storage. Cold-damaged brown leaves can be removed in spring for aesthetic cleanup.

Dietes bicolor tolerates mild to moderate humidity levels and can handle dry air quite well, making it adaptable to various environments. The plant is not demanding about humidity and will grow successfully in typical outdoor or indoor conditions. However, avoid excessively high humidity as this can promote crown rot and fungal issues like gray mold on leaves. Good air circulation is important to prevent disease, especially in humid environments.

Dietes bicolor produces flat, pale yellow flowers about 2-3 inches (60mm) in diameter with distinctive dark brown to purple blotches at the base of the outer tepals, often surrounded by an orange outline. Each flower lasts only one day, but plants bloom continuously from spring through fall, with approximately two weeks of rest between flowering periods (hence the name 'Fortnight Lily'). The flowers rise above the foliage on branched stalks and resemble small Japanese irises. After flowering, club-shaped seed capsules develop containing dark brown seeds.

Yes, Dietes bicolor is primarily an outdoor plant thriving in USDA hardiness zones 8-11. In these zones, it's a reliable evergreen perennial that can be planted year-round. The plant tolerates coastal conditions but has poor salt tolerance. In colder climates (zones 7 and below), grow it as an annual or in containers that can be moved indoors for winter.

Prune brown or yellow leaves by cutting them cleanly at the base near the crown. After flowers finish blooming, cut flower stalks down to the rhizome level to discourage rot and encourage new blooms. Remove seed pods if you want to reduce self-seeding. If the plant has been neglected and has more brown leaves than green, you can cut the entire plant back to ground level in early spring—it will regrow vigorously. Never cut green leaves or stems until they've fully dried, as this affects future blooming.

Divide and repot Dietes bicolor every three years or when the clump becomes overcrowded and flowering decreases. The best time is after flowering ends or in autumn. Dig up the entire clump and use a sharp, sterilized knife or shovel to separate the rhizomes into sections, ensuring each division has several leaves and healthy roots. Plant divisions 12-24 inches apart, with rhizomes about 1 inch deep. The plant transplants easily and establishes quickly in its new location.

Dietes bicolor propagates easily through division or seeds. Division is the quickest method—separate rhizome clumps in autumn or after flowering, ensuring each section has leaves and roots. For seeds, sow in spring or autumn in moist seedling mix at 59-68°F (15-20°C). Seeds have a hard coating, so soak for 12 hours or scarify before sowing. Barely cover with soil as light aids germination. Seeds typically germinate in 18-20 days but can be variable. Note that seed-grown plants take 2-3 years to flower and may show less uniformity than divisions.

The main pest problems are nematodes and scale insects, which can cover foliage and cause severe damage. The plant may also attract Narcissus Bulb Fly and Potato Aphid. Disease issues include crown rot (leaves turn red, yellow, or purplish), root rot, rust, and leaf spot (irregular brown or yellow spots on leaves). Good drainage prevents most root problems. High humidity can cause gray fungal growth on leaves. Despite these potential issues, Dietes bicolor is generally pest and disease resistant with no serious problems when given proper growing conditions.

Yellow leaves on Dietes bicolor typically indicate water issues, disease, or natural leaf aging. Inconsistent watering—either too much or too little—is the most common cause. Ensure the plant receives about 1 inch of water per week during dry periods. Crown rot can cause leaves to turn yellow, red, or purplish. Leaf spot disease creates irregular yellow or brown spots. Some leaf yellowing is normal as older outer leaves die back naturally. Remove yellow leaves at the base with clean cuts and ensure good drainage to prevent fungal issues.

Brown leaves on Dietes bicolor are commonly caused by frost damage, water stress, or disease. Temperatures below 25°F cause leaf browning—remove damaged foliage in spring. Irregular watering leads to brown tips and edges. Leaf spot disease causes irregular brown spots. Cut off brown flower stalks at the rhizome to prevent rot. If most of the plant has brown leaves due to neglect, cut everything to ground level in spring and provide fertilizer and water—the plant will regenerate fresh green growth. Always make clean cuts at the leaf base when removing damaged foliage.

Dietes bicolor is pollinated by insects, primarily bees. The flowers provide nectar at the base of the outer tepals. When a bee pushes between the outer tepal and style branch to access nectar, pollen is deposited on its back. This pollen is then transferred to the next flower the bee visits. The presence of flowering Dietes bicolor plants attracts various pollinators to gardens, and the flowers subsequently draw insectivorous birds that feed on the visiting insects.

In traditional South African culture, the roots of Dietes bicolor were used as a charm to protect and strengthen the wearer. Beyond this folkloric use, the plant has primarily ornamental value in modern landscapes. It's widely used for beautification in public gardens, commercial premises, and roadsides due to its attractive evergreen foliage and long flowering season.

Fortnight Lily is a low-maintenance plant that requires minimal attention, making it an excellent choice for beginners.

New growth will sprout from the top of the plant as it grows upwards.

Fortnight Lily should be watered regularly, allowing the soil to dry out between waterings.

Fortnight Lily loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

Fortnight Lily requires abundant, bright and direct light. Placing it less than one foot from a window is the best way to make sure the plant receives enough light to survive and thrive. Depending on your region, however, the current weather can affect the placement of the plant in your home. For example, in some areas the sun may be too direct and intense, so it's best to place it farther away from the window. You may also need to adjust your placement according to the season as the sunlight can change intensity over the course of the year. If you live in a region with significant temperature fluctuations, such as a desert, you may need to place the plant a bit farther away from the window to avoid extreme heat or cold. With some care and attention, your Fortnight Lily will be sure to bring you many years of beauty and enjoyment.

The Fortnight Lily should be transferred to a new pot once it has increased in size two-fold, or on an annual basis, whichever occurs earlier. Replacing the soil with fresh potting soil containing all the necessary nutrients, is sufficient enough to support the growth of the plant, thus avoiding the need to use fertilizer. It's important to note that plants derive their energy from the sun and not fertilizer.

Ploi does not possess verified information regarding the toxicity of this particular plant. In the event that you, a member of your family, or a pet ingests plant material with an unclear toxicity level, it is highly recommended to seek the advice of a medical professional.

During the cold period, it is common for Fortnight Lily to go dormant and their growth may slow down, so waterings should be spaced out more during this period.