Lisianthus is a tender perennial flower that is often grown as an annual. Featuring large purple and white bell-shaped flowers with flaring lobes that bloom on one or more upright stems, lisanthus is somewhat finicky to grow, but the effort is clearly worthwhile for anyone interested in cut flower work. It is often celebrated as a flower that looks like a rose but lasts longer in the vase and is in great demand for bridal bouquets and other special-occasion flower arrangements. Lisianthus plants are most commonly available in white, pink, purple, and cream, but you may occasionally see yellow or red flowering plants for sale. The flower's foliage is dark green and lance-shaped, and slightly succulent in texture.
In its usual use as an annual garden flower, lisianthus planted from seeds grows slowly, reaching flowering maturity in five to six months. Thus, most gardeners plant them from commercial nursery plants that were started from seed in greenhouses the previous fall so they will erupt in fluttery, layered blooms in spring.
|Common Name||Lisianthus, prairie gentian, bluebell gentian|
|Botanical Name||Eustoma russellianum (prev. Eustoma grandiflorum)|
|Plant Type||Herbaceous perennial, usually grown as an annual|
|Mature Size||1–3 ft. tall, 6–12 in. wide|
|Sun Exposure||Full sun|
|Soil Type||Moist, well-drained soil|
|Soil pH||Neutral (6.5—7.0)|
|Bloom Time||Summer, fall|
|Flower Color||Purple, pink, white|
|Hardiness Zones||8–10 (USDA), borderline in zone 7|
|Native Area||Central North America|
Lisianthus will grow in all zones as an annual plant, but it can also perform as a perennial in areas with above-freezing winters (zones 8 and warmer). While you can grow lisianthus from seed, doing so is not advisable for beginner gardeners since the tiny seeds take a long time to mature into blooming-sized plants unless cultivated under strictly maintained greenhouse conditions.
Your best bet is to plant nursery starts in spring, carefully choosing lisianthus plants with buds or flowers already emerging (even greenhouse growers can sometimes produce plants that favor foliage over flowers). But understand that lisianthus has earned its reputation as a fussy plant, Ideal soil, careful watering, precise feeding, frequent staking—these are the ingredients for growing lisianthus plants with the perfect flower stalks that are so prized by floral arranging hobbyists.
Plant your lisianthus in a spot that boasts full sun, where the plant can get at least six to eight hours of sunlight a day. If you live in an area with very hot summers, the plants will benefit from some afternoon shade, but don't worry about it too much. The more consistent sunlight your lisianthus gets, the better foliage and flowers your plant will have.
Choose a planting site with well-draining soil. Raised beds are ideal, as are containers. Lisianthus prefers soil that is rich in organic matter such as manure, compost, or leaf mold. The soil should be well-draining and should not remain waterlogged, as that can lead to root rot.
Lisianthus falls into that small category of flowers that cannot tolerate a very acidic soil pH. Nor does it like alkaline soil. If you don’t maintain a soil pH between 6.5 and 7.0, your lisianthus plants will exhibit yellowing of the leaves and decreased vigor.
Keep your lisianthus plants moist, but never allow them to remain soggy. Overwatering your plant can encourage the development of fungal diseases. If you have the time to create one, a drip irrigation system can be ideal for giving your plants water at their roots, right where they need it. The plant's soil should be allowed to dry out in between waterings, but don't let the plants themselves dry out. Getting the irrigation timing correct can be a challenge when growing lisianthus. About 1/2 inch of rainfall/irrigation per week is fairly ideal for lisianthus.
Temperature and Humidity
Lisianthus is a heat-loving plant that is native to areas where the days are relatively dry and the summer nights are warm, though they will flower more profusely if given more moisture. They do not mind hot conditions and can even tolerate a bit of drought, though this may reduce the flowers. But lisianthus is not tolerant of humidity and does not do well in damp climates with limited sun, such as those found in the Pacific Northwest.
Lisianthus flowers need a constant nutrient stream to produce well-branched plants with abundant blossoms. Choose a flower fertilizer with one and a half times the amount of potassium as nitrogen, and apply it according to package directions throughout the plant's growing season. LIsanthus require feeding at least monthly, and more often if rainfall is frequent.
Types of Lisianthus
There are many different cultivars of lisianthus, distinguished by their color and size. Most lisianthus plants bloom best in early summer, although an increasing number of cultivars are being introduced that continue to bloom through the hottest summer months and into fall.
- ‘Balboa’: This variety is full of blooms, boasting upwards of a dozen flowers per plant, all in shades of blue.
- ‘Flamenco’: Although gardeners seem to prefer double-flower lisianthus plants over single flower ones, the heat tolerance of this variety makes this type worth a try.
- ‘Maurine’: This plant is a semi-dwarf, heat-tolerant variety, making it the perfect size to grow in containers on your deck and patio.
- Sapphire Pink Rim': This variety is a compact form (5 to 6 inches tall) with white blooms with pink edges.
- 'Echo Blue': This tall variety (up to 34 inches) has dark blue flowers and blooms from midsummer right up to frost.
If you've successfully grown lisianthus plants that have erupted in blooms come early summer, there's a good chance that you can coax a second act from the plants in the fall. To do so, it's important to prune the plants in a certain manner.
Start by cutting the stems of the plant back to the basal rosette of foliage after their initial bloom. Then, give your plants all the pampering they crave, including thorough weeding, regular irrigation, and plenty of fertilizing. By mid-September, you should be harvesting new blooms to pretty up your fall bouquets.
In warm-winter zones where lisianthus is perennial, it is sometimes propagated by taking root cuttings in winter:
- After cutting back the stems and foliage to just above ground level, dig up the entire plant with a shovel.
- Divide the root ball into sections with a sharp knife or trowel, making sure each section has some greenery or growth buds.
- Immediately replant the pieces in their desired locations, and water thoroughly. New growth should begin within a few weeks.
How to Grow Lisianthus From Seed
Lisianthus seeds are very small—barely larger than dust particles—so growing plants from seeds is not a very practical option. When purchased commercially, the seeds are often prepared in pelleted form to make them easier to handle. In cold-winter zones, the seeds must be started indoors in late fall. In warm-winter perennial zones, you can plant the seeds directly in the garden in late summer. But be aware that starting lisianthus from seeds is a long, drawn-out process that is best tackled by serious gardeners.
For indoor seed starting, use trays or small pots filled with a porous seed-starter mix (fine peat moss plus fine vermiculite). Moisten the potting mix, the sow the seeds on the surface. Cover the tray or container with a plastic dome or clear plastic bag and set it under grow lights (the seeds need 16 hours of light per day to germinate and sprout). For the next two weeks, carefully monitor the temperature, making sure to keep it between 70 and 75 degrees Fahrenheit.
When seedlings appear, remove the covering and lower the grow lights to just above the seedlings. Temperatures can now be allowed to fluctuate a bit more, but should still be kept above 60 degrees and below 75 degrees. Continue growing the seedlings, making sure the growing medium stays moist but not saturated. Feed with a general-purpose fertilizer diluted to half-strength each week.
After seven or eight weeks, the developed seedlings can be transplanted into their own containers filled with potting mix. As you continue to grow the seedlings, make sure temperatures do not exceed 75 degrees, or you risk sending the plants into a dormancy phase (known as "rosetting").
Several months later, as spring arrives, your seedlings should be about 4 inches tall and can be hardened off with increasingly long visits to the outdoors over a week or so, until they are toughened up for planting in the garden. However, don't plant until all danger of frost has passed.
Potting & Repotting Lisianthus
Shorter varieties of lisianthus grow well in containers filled with ordinary potting medium. Their colors combine well with many plants in mixed containers, such as dianthus, coreopsis, baby's breath, and snapdragons. In zones where they can remain outdoors as perennials, potted lisianthus plants require annual repotting, going up one pot size each time.
Though it is challenging, some gardeners find it possible to keep potted lisianthus plants growing indoors and flowering through the winter. The trick is giving them enough bright light, controlled temperatures, and preventing common indoor pests such as mites and fungus gnats from decimating them. During the indoor winter months, give the plants a weak monthly feeding with diluted fertilizer.
In cold-weather zones where lisianthus dies out, simply pull the plants from the ground after the blooms are complete, or when cold weather causes the plants to wither.
In warm-winter zones where lisianthus grows as a perennial, simply keep cutting back faded flower stalks for continued blooms; reduce feeding during the winter months. Zone 7 is a transitional zone for lisianthus; it may survive the winter if you cut back the plants to ground level and cover it with a light mulch until spring.
Common Pests & Plant Diseases
Fungus gnats are one of the most common pests lisianthus plants deal with, and they can travel with the plants from early on in the greenhouse stage. The flying adults aren’t the problem, but rather the larvae that live beneath the soil and feed heavily on roots, devastating your plants. To rid your plant of fungus gnats, focus on not overwatering. You can also treat the plant with a mild insecticide or neem oil until all signs of an infestation have gone. Mites are another common pest, which can also be treated with neem oil or insecticide.
Lisianthus plants can also be susceptible to some plant viruses and stem cankers. Affected plants must be removed and discarded.
How to Get Lisianthus to Bloom
Problems with poorly blooming lisianthus can usually be traced to cultural issues. The plants need a good amount of sun, and like many heavy-flowering plants, they need regular feeding. Lack of nutrients is the most common reason why these plants fail to bloom robustly. Proper watering is also critical. Lisianthus needs regular deep watering applied just as soon as the soil dries out, but it does not like to sit in wet soil.
Proper sun, proper watering, and proper feeding: This is the formula for full-blooming lisianthus plants.
Common Problems With Lisianthus
Lack of full flowering is the most common problem with lisianthus, but there are several other common complaints.
My Garden Plants Topple Over
The long stems that make lisianthus flowers so elegant in the vase can be a drawback in the garden, as the stems are often too thin to support the double-bloomed varieties. Don’t let this discourage you, though, as there are so many beautiful and functional grow-through supports on the market, from nearly invisible support rings and grids to decorative willow, or metal cage-like tuteurs.
My Cut Flowers Don't Last
There are several tricks to making sure cut lisianthus flowers will last in the vase for up to four weeks:
- Harvest the flower stems early in the day, as the first buds are just opening. Use sharp scissors to cut the stem off just above the basal foliage. The light-green buds will gradually transform into full color as the flowers open.
- Remove the leaves below the waterline, and recut the stems are you arrange the flowers in the vase.
- Replace the water every two or three days—or whenever the water begins to get cloudy.
- Adding 1/4 cup of sugar to each quart of water will prolong the blooms. Subsequent water changes require just 1/8 cup of sugar per quart.
- Add a few drops of household bleach to the water to reduce bacteria.
My Garden Flowers Aren't Prefect Enough for Cut Arrangements
Remember, the lisianthus plants that florists use in commercial flower arrangements have been grown in carefully controlled greenhouse conditions, with regular feeding, controlled watering, and lots of chemicals to control pests and diseases. Don't expect all your outdoor garden flowers to be this perfect. If you are serious about flower arranging, make sure to plant a large patch of lisianthus, and be prepared to tend them carefully to ensure the best possible blooms. In a large patch, your chances for a good number of perfect flower stems are much better.
But even when imperfect, lisianthus flowers are great citizens of the mixed border. The answer may be to enjoy them where they are rather than to insist on perfect flowers for cutting.
How do I use lisianthus in the landscape?
Lisianthus is a favorite of gardeners who practice cut flower arrangements, but it is excellent in any bed or border garden. The delicate appearance of lisianthus plants makes them the perfect addition to a cottage garden alongside other English classics like scented stock and delphiniums. It also lends itself well to containers and sometimes even works as a houseplant.
I have trouble growing lisanthus—are there some similar flowers I can try?
One of lisianthus' claims to fame is that it looks like a tea rose, so if you have trouble growing it, try an actual tea rose, which is usually quite simple to grow. You won't be able to get the deep blue lisianthus color in a tea rose, but there are plenty of lavender tea rose varieties that can fill in for cut arrangements.
In the garden, balloon flower (Platycodon grandiflorus) or any number of other bellflowers can create the same visual impression as lisianthus.