Q • Can I keep the seed pods from lisianthus and start plants from seed the following year? If so, how do I go about doing this? A • Harvest seeds when the pods start to dry out. Seeds of lisianthus, or the Prairie gentian (Eustoma grandiflora), should be started in winter, about 10 to 12 weeks before the last frost. With an average last frost in mid-April here in the St. Louis area, you’re targeting a time around late January to mid-February for seed sowing.
Lisianthus resents transplanting, so use peat pots to start them, as this will allow you to transplant with minimal disturbance to the root system. Place several seeds in individual peat pots and then cull out all but the strongest seedling in each pot once they are off and growing.
Seeds are quite small and need light in order to sprout, so just gently press them into the top surface of a well-drained mixture but do not cover them with soil. Germination occurs best at 65 to 75 degrees, and it may take up to three weeks before the seeds sprout. Grow plants at cooler temperatures, in the 55-to-60-degree range. A strong light source will be necessary to keep plants from getting too leggy. Once the seedlings are 6 inches tall, pinch out their tips to encourage branching.
Set your plants outdoors about a foot apart after all chance of frost is past. Choose a sunny site with excellent drainage. Lisianthus prefers to dry out some between waterings, but should not be subjected to drought. They also do very well in containers where they can lean on their neighbors or sprawl over the edge of the pot.
Write to Chip Tynan of the Missouri Botanical Garden at email@example.com or Horticultural Answer Service, 4344 Shaw Boulevard, St. Louis, 63110.