Lisianthus

Lisianthus (Eustoma grandiflorum), also called prairie gentian, is a showy flower with large bell-shaped blooms in pink, white, and lavender. It is native to the central United States, from Nebraska south to Texas.

The plant is more typically grown as an annual, though it is described as a biennial as well. Standard cultivars grow about 18 to 30 inches (46–76 cm) tall, while some dwarf varieties reach only 6 to 8 inches (15–20 cm). Flowers open from summer until the first frost.

Sowing. Start seeds indoors 10 to 12 weeks before the last spring frost. Seeds are very small, and the trade seed grower recommends transplanting, sowing into a 288-cell or deep-cell seedling tray 12 to 13 weeks before planting out.

Germination. Seeds need light to germinate, so cover them with only a thin layer of fine vermiculite to help limit algae. Germination takes 10 to 15 days at 68–72 °F (20–22 °C). Under glass, sow seed at 13–16 °C (55–61 °F) in autumn or late winter.

Timing to bloom. Plants can take about 5 months from planting to first bloom, so seed-grown plants need a long season. Pinching back the plant encourages branching.

Light. Lisianthus does best with full morning sun and afternoon shade. Under glass, give it full light, with bright filtered light while it is in bloom.

Soil. It grows best in average, moist, well-drained soil. The seed grower notes that well-drained soil high in organic matter suits it.

Watering and feeding. When growing, water freely and feed with a balanced liquid fertilizer every 2 to 3 weeks; water sparingly in winter. The plant is noted for good drought tolerance. Support the stems as they grow.

Lisianthus has no serious insect or disease problems, but watch for viruses and stem cankers, and note that it is susceptible to a number of fungal diseases. It is generally pest-free, though it may be susceptible to grey moulds.

Seed-grown plants are also known for being difficult. The seed grower says lisianthus can be quite difficult to grow, and many gardeners buy plugs or transplants instead.

Lisianthus is an excellent cut flower.