Lisianthus, Eustoma grandiflorum, is also called prairie gentian and is most often sold as a pot plant. It is grown above all as a cut flower, with rose-like blooms on stems up to 100 cm. In a vase the flowers last 2-3 weeks. You can grow it from seed in most of the UK and northern Europe, but it takes planning, because it takes around 24 weeks from sowing to the first flower.
Why lisianthus is sown as early as January
Lisianthus is an annual and comes from warm grasslands in the southern United States and Mexico. The breeder Sakata, which is behind the Rosita and Mariachi series, reckons on 22-24 weeks of growing time for its cut flower varieties. That is just over five months. Sow in January and the first flowers come in July. Sow in March and you have to wait until August or September.
Mariachi belongs to Sakata's group 2, which is bred for sowing in January-April and flowering in summer. That fits well with raising plants indoors in a cool climate. We mark all our lisianthus as varieties for growers who like a challenge. The long period indoors and the sensitivity to temperature are the reasons.
From seed to vase month by month
| Month | What happens and what you do |
|---|---|
| January | Sow on the surface of the compost at around 21 °C. The seeds germinate after 10-20 days. |
| February | Lower the temperature to 15-20 °C. The plants are small and grow slowly. |
| March | Keep the compost evenly moist and the temperature right. The risk of rosetting remains until the plant has 2.5 pairs of leaves. |
| April | Four true leaves after 10-12 weeks. Pot on into individual pots. |
| May | Harden off the plants. Prepare the bed and put up the netting. |
| Late May-June | Plant out when the nights stay reliably above 10 °C. |
| July-September | Harvest when the first flower has opened. |
How to sow the light-germinating seeds
Compost: Fill a plug tray with fine, free-draining seed compost and water it before you sow. Sow 1-2 seeds per cell. That way you do not have to separate the tiny seedlings, and if two come up in the same cell, snip off the weaker one.
Sowing: Place the seed on the surface and press it down lightly. The sowing depth is 0.1 cm, which means no compost on top. If you want to hold moisture better, we recommend a thin layer of vermiculite.
Warmth and moisture: Stand the tray at around 21 °C under a clear lid. The compost must not dry out during germination.
Light: The seeds need light to germinate, so put them under a lamp or on a bright windowsill, never in a dark cupboard. In January the light from a window is rarely enough, and our guide to grow lights gives you distances and hours.
The first twelve weeks
Lisianthus grows slowly at first. It takes 10-12 weeks before the plant has four true leaves, so a January sowing stays in the tray right into April. That is normal and not a sign that something is wrong.
Once the seeds have germinated, lower the temperature to 15-20 °C and give 14-16 hours of light a day under the grow light. At four true leaves, pot on into individual pots. Handle the roots gently and do not wait too long. According to Sakata, plants that have become root-bound in the tray flower earlier, on shorter stems, and establish less well. Give a weak feed after potting on, but not a nitrogen-rich fertiliser. Too much nitrogen gives soft stems and paler colours.
When the plant forms a rosette
Rosetting is a known problem with lisianthus and the reason temperature matters so much. The plant forms a flat ring of leaves close to the soil and sends up no stem, and it is hard to get it out of that state again. The risk lasts from sowing until the plant has 2.5 pairs of leaves.
What triggers rosetting is the wrong temperature and drying out. Sakata states that the plants should not stand warmer than 26 °C by day and 18 °C at night, and that nights below 10 °C also increase the risk. At home it happens easily if the sowing is left on the heat mat or above the radiator after germination. Commercial growers sometimes chill the freshly sown tray in darkness at 10 °C for 3-5 weeks to reduce the risk, but for a home grower it is simpler to keep to the temperatures above.
Planting out, soil and netting
Plant out only when the nights stay reliably above 10 °C, which in most of the UK and northern Europe means late May or June. How to harden off the plants over the last few days is covered in our article on starting seeds indoors.
Position: Full sun. We recommend a greenhouse or polytunnel if you have one, because rain on open flowers leaves spots on the petals. Outdoors, choose a sunny, sheltered spot.
Soil: Free-draining and rich in organic matter. Lisianthus is sensitive to acidic soil, and Sakata gives pH 6.5-7.2 for the growing medium. Add lime if your soil is acidic.
Spacing: 15 cm between plants in every direction.
Netting: Stretch a net with 15 cm squares over the bed when you plant, so that each plant grows up through its own square. The varieties reach 60-100 cm, and the tallest need a second net higher up.
Watering: Generously until the stems start to stretch, then evenly. Water at soil level, not over the plants.
Harvest and vase life
Cut the stem when the first flower has opened. Some growers cut off the first flower for a small vase and harvest the rest of the stem when flowers two and three have opened. Put the stems straight into lukewarm water, around 20 °C, and remove the leaves that would end up below the waterline.
Lisianthus lasts 2-3 weeks in a vase. Sakata states that cut flower food in the water extends vase life by 40-50 percent compared with plain water. If you want bouquets as early as June, while the lisianthus is still growing, you can add faster annual cut flowers.
Florea's seven varieties
Our lisianthus seeds come in seven varieties from four series. All are cut flower varieties, and height and flowering time differ slightly.
| Variety | Colour | Height | Flowering |
|---|---|---|---|
| Rosita Apricot | Apricot with a pink tone | 80-100 cm | June-August |
| Mariachi Yellow | Soft yellow | 80-100 cm | June-August |
| Mariachi Lime | Lime green | 100 cm | June-August |
| Arena Champagne | Cream white with rosé | 75-85 cm | June-August |
| Arena Apricot | Apricot and peach | 60-90 cm | July-September |
| Croma Champagne | Cream, rosé and beige | 60-90 cm | June-August |
| Croma Yellow | Pale yellow | 60-80 cm | July-September |
Rosita Apricot has double flowers in sprays, meaning several flowers on each stem. Mariachi has extra double flowers that resemble camellias, and Mariachi Lime reaches around 100 cm. If you want to spread the harvest, choose one variety that flowers June-August and one of the two that flower July-September. A packet contains 20 seeds, enough for a row of up to 3 metres with 15 cm between plants.
Common mistakes
Covering the seeds with compost: They germinate in light. Leave them on the surface.
Leaving the sowing somewhere warm: 21 °C is right for germination, not for the plant. Lower the temperature to 15-20 °C as soon as the seeds have germinated.
Letting the compost dry out: Drying out triggers rosetting, just like the wrong temperature. Check the tray every day for the first 12 weeks.
Keeping the plants in the tray too long: Root-bound plants flower early on short stems. Pot on at four true leaves.
Water on the flowers: Rain and overhead watering on open flowers leave spots. Grow under cover if you can and water at the roots.
Author: Emma Vogiatzi
Fact-checked by Erik Hoekstra
Last updated 2026-10-19