Lisianthus only recently has enjoyed popularity as potted plants. It’s probably been only in the last ten years they’ve been available at all and really only the last five years since they’ve become more widely available. Sold as blooming potted plants, they are found alongside such stalwarts as kalanchoe and gloxinia. Properly grown, lisianthus features large, delicate looking flowers in a variety of colors and will bloom profusely from a busy plant for several months.
Although growers are still experimenting with the best ways to cultivate lisianthus, they are frequently available year-round. Keep in mind that they do best in the early spring months before it gets truly warm. Like other potted plants, lisianthus is not really designed to survive permanently as potted houseplants. Instead, they are frequently discarded once the bloom has faded. For those who would like to keep theirs, be prepared for somewhat of a challenge, and reduced vigor for the next season.
- Light: Lisianthus thrives in bright, indirect light. They dislike intense heat, which can actually reduce flowering, so do not expose them to harsh summer sun in July and August. In winter, more light is permissible.
- Water: During the growing season, water frequently, letting the soil dry out between waterings. Do not let them experience drought-like conditions. Plants will benefit from being misted regularly to improve humidity.
- Soil: A rich, peat-based potting soil with excellent drainage is beneficial. Poor drainage can rot their roots, so make sure the lisianthus is never left in standing water.
- Fertilizer: Feed with a weak liquid fertilizer throughout the growing season. Cut fertilizer back to once a month or so in the winter.
Lisianthus is still new enough on the potted flower scene that few home growers have experience propagating them. They can be grown from seed, but their size can be surprising. This plant will want to grow somewhat larger than a grower may be used to before flowering. They can also be grown from stem-tip cuttings from new plants. It’s best to do cuttings in the spring.
Repot lisianthus in the early spring, when new growth emerges. Most people, however, do not keep lisianthus from one season to the next.
There is only one species regularly seen in the trade: L. russelianus. This plant is sometimes labeled the prairie gentian. Within this one species, growers have developed cultivars in different colors, and home growers are encouraged to look for the color they like best. All cultivars have the same growing requirements, so don’t treat any one plant different from others.
Lisianthus is not particularly difficult to nurse through a single growing season but significantly more difficult to keep alive over the long term. To make the plants more attractive to indoor gardeners, most lisianthus is treated with growth retardants during nursery production. They are also pruned for maximum buds so the flower will be more impressive. When shopping for lisianthus, look for a plant with a multitude of unopened buds, so they’ll have more flowers. Remove dead and dying flowers to increase the length and intensity of the bloom.
The downside here, of course, is that the plants rarely have the stamina and vigor to survive and thrive for another season. In terms of pests, lisianthus is especially susceptible to fungus gnats, which can spread fungal disorders. They are also vulnerable to mealybugs, mites, and aphids. Signs of infestation include tiny webs on plants, clumps of white, powdery residue, or visible insects on the plant. Treat infestations as soon as possible to prevent them from spreading to the rest of the indoor gardening collection. As always, start with the least toxic treatment option first, progressing to more serious chemicals if the initial efforts fail.