Growing this elegant cut flower will set your garden apart! With showy, rose-like blooms that are long-stemmed and come in a wide range of colors, these beauties are truly breathtaking. Learn how to plant, grow, and care for lovely lisianthus.
About Lisianthus
Lisianthus (Eustoma grandiflorum), also called prairie gentian, is a cut flower star for a good reason–they’re gorgeous and have a long vase life! With multiple ruffled flowers in single or double blooms reminiscent of roses. They flower on long stems in colors ranging from white through pinks, reds, lilac, blues, and even bicolor varieties.
There are many lisianthus varieties available, organized into four groups based on when they bloom and what climate they need. Lisianthus are hardy in USDA zones 8 to 10. While they are perennials in their native range of the southwest US, they are usually grown as annuals.
If you follow flower farmers on social media, you’ll see them holding huge armloads of lisianthus blooms or explaining why they no longer bother. The flowers can be challenging to start from seed. The extended time it takes for seedlings to be ready for transplant means lots of time for something to go wrong. You’ll need your A-game, but that doesn’t mean it can’t be done!
However, home gardeners can grow from transplants or plugs if they can find them at nurseries or online retailers. Or, we’ll show you how to start lisanthus from seed. For avid gardeners, it’s worthwhile for such a breathtakingly beautiful flower.
Lisianthus likes full sun, about 6 to 8 hours daily, but afternoon shade is beneficial in regions with sweltering summers. Good drainage is necessary. Soil rich in organic matter is ideal, and a pH of 6.5 to 7.0 is the sweet spot. Amend beds with leaf litter, compost, and aged manure.
If your flower patch is short on room, don’t despair; these flowers grow well in containers on the deck or patio.
When to Plant Lisianthus
In most locations, you can transplant lisianthus into outdoor beds about 4 weeks before your last frost date.
If you are growing from seed, you can count backward from your transplant date—a long way back. Lisianthus can take 3 to 5 months to be ready to plant out. For most of us, start about 4 months before your transplant date.
Lisianthus likes cool weather to become established when transplanted and can take some moderate frost even as seedlings. Light frosts won’t hurt it, but if you get a cold snap, about 20F or colder, you’ll want to cover them with frost cloth for the night unless covered in snow.
How to Start Lisianthus From Seed
Lisianthus seeds are tiny, so buying pelleted seeds can make them much easier to handle. Soil blocks work well, but lisianthus can also be planted in small cell trays.
Pre-moisten your seed starting mix, then sow one seed per block or cell.
Lisianthus seeds need light to germinate, so press them lightly to ensure good seed-to-soil contact and then apply a thin layer of vermiculite.
Keep the seed starting mix evenly moist (but not drippy wet) until germination, which can take two weeks. A humidity dome or plastic covering will help keep the moisture in.
After they sprout, remove the humidity dome and let the medium slightly dry out between waterings. Don’t let them get too dry and wilt. With many potting mixes, the soil will change color a bit when dry, but I like to feel them to be certain. If they’re dry to the touch or very lightweight, it’s past time to water.
Fertilize weekly with a dilute solution. The small seedlings will be in their trays or soil blocks for months. Eventually, they will use up the available nutrients and stop growing without supplemental fertilizer.
Don’t let the trays get too warm. If temps get high for a while, above 75-80℉, baby lisianthus may start to rosette and put out a bunch of growth from the base. Those that do this will likely never flower. Lisianthus will still be small when transplanted–probably only an inch tall. Ideally, they should have four sets of leaves.
When transplanting, space the seedlings 4 to 5 inches apart and stake or net them when you plant.
They’ll need support by staking or using netting, and it’s easier to do it right away than to forget and try to weave stems through the netting later. Their heads get heavy with the huge blooms, and they will likely flop.
Growing
Lisianthus are drought tolerant once established and will continue to blossom for many weeks, often until frost. Keep the weeds down and provide support for taller varieties.
Lisianthus can develop water spots on their petals with overhead irrigation, so a drip irrigation setup is handy. Flower farmers often grow lisianthus in hoop tunnels to protect their petals from the rain. But if you don’t have such fancy equipment, you can still grow them!
Mulch lisianthus to keep the soil shaded, help maintain moisture, and keep weeds down.
Types
‘Rosanne Black Pearl’ is a dark, violet bloomer–think eggplant color. Combine it with lighter cream-colored flowers for a stunning bouquet or grow it as a strip of elegant border flowers in a bed.
‘A°ù±ð²Ô²¹ III Red’ is a deep pink with blooms that will fool anyone into thinking they are a rose.
‘Balboa Blue Rim’ are two-tone blooms: white centers and purple ruffled edges.
‘First Love’ is a blushing pink and white with fully double blossoms. Gorgeous in bunches, this flower looks like a bridal bouquet all by itself.
Harvesting
Lisianthus bloom from the bottom up, so the lowest blooms open first, like gladiola. They can be harvested any time after the lower blooms begin to open.
Cut deeply to encourage future long stems.
Strip off all foliage that will be in the vase.
Fresh-cut lisianthus will last up to 15 days in the vase.
Gardening Products
Wit and Wisdom
Because lisianthus is so time-consuming to start from seed, you may wish to purchase started plants or plugs. Let someone else do the hard part.
, especially during the seedling stage. After sprouting, keep them cooler, about 50-65℉. Some varieties may rosette at room temps.
Pests/Diseases
Fusarium wilt
Root pathogens as seedlings due to the long holding time before transplanting
Andy Wilcox is a flower farmer and master gardener with a passion for soil health, small producers, forestry, and horticulture. Read More from Andy Wilcox