How to Grow and Care for Lisianthus (Prairie Gentian)

Lisianthus (Eustoma spp.) are tender perennials or biennials often grown as annuals. They grow about 1 to 3 feet tall, featuring bell-shaped flowers with flaring lobes that bloom on one or more upright stems.

Flowers commonly come in white, pink, purple, and cream, and occasionally yellow, apricot, rose, or red. Foliage is dark green, lance-shaped, and slightly fleshy in texture.

Lisianthus is in great demandfor bridal bouquets and other special occasion arrangements. Starting with seeds, plants take up to six months to flower so most home gardeners start with commercial nursery plants and grow lisianthus as annuals.

Lisianthus Care

Lisanthus can be somewhat finicky to grow and care for but is worth the effort. They look good in mixed containers and borders and make long-lasting cut flowers.

• Plant nursery-grown lisianthus seedlings as annuals for best flowering in zones 7 and lower.
• Plant in organically rich soil with a neutral pH.
• Provide 6 to 8 hours of sun daily, and warm, dry conditions.
• Feed regularly with high-phosphorous fertilizer.
• Deadhead consistently for repeat blooms.

Light

Plant lisianthus in full sun, where it receives six to eight hours a day. In areas with very hot summers, a little afternoon shade won't hurt but consistent light exposure is key for best flowers and foliage.

Soil

Lisianthus prefers soil rich in organic matter such as manure, compost, or leaf mold. Soil should be well-draining and not remain waterlogged, which can lead to root rot. Raised beds and containers work well.

Lisianthus flowers need a balanced soil pH between 6.5 and 7.0. Soil too acidic or alkaline causes yellowing foliage, less vigor, and fewer blooms.

Water

Give lisianthus flowers about 1 inch of water per week to keep the soil moist but not soggy. Allow it to dry out slightly between waterings. Drip irrigation is an ideal watering method if you want to keep a consistent schedule, once you've figured out how often you need to water your flowers.

Temperature and Humidity

Lisianthus prefers warm environments, thriving in temperatures between 60°F and 75°F. They tolerate drought but suffer in high humidity. It's only hardy in zones 8 and higher; lower than that, and lisianthus tends to be grown as an annual. It may survive temperatures as low as 28°F.

Fertilizer

Feed lisianthus regularly with flowerfertilizer that has one and a half times the amount of phosphorous as nitrogen. Apply it according to package directions throughout the plant's growing season. A constant nutrient stream is necessary to produce well-branched plants with abundant blossoms.

Types of Lisianthus

Lisianthus varieties are distinguished by color and size with most blooming in summer. New cultivars are being introduced that continue to bloom into autumn.

• 'Balboa': This variety features more than a dozen flowers per plant, all in shades of blue.
• 'Flamenco': A heat-tolerant single flowered series in rose pink, white, and yellow.
• 'Maurine': A semi-dwarf, heat-tolerant variety perfect for containers on your deck and patio.
• Sapphire Pink Rim': Compact (5 to 6 inches tall) with white blooms and pink edges.
• 'Echo Blue': This tall variety (up to 34 inches) has dark blue flowers and blooms from midsummer up to frost.

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Pruning

Pruning lisianthus in summer can encourage a second blooming in autumn. Cut the stems back to the basal rosette after the initial bloom has finished. Water and fertilize them consistently and keep the area free of weeds. Look for a second flowering around mid-September.

Propagating Lisianthus

In warm-winter zones where lisianthus is perennial, it is sometimes propagated by dividing the root ball in winter. You need a shovel, a sharp cutting tool, and a trowel.

1. Cut back the stems and foliage to just above ground level.
2. Dig up the entire plant with a shovel, keeping as many roots as possible including the long tap root.
3. Divide the root ball into sections with a knife or trowel. Include some greenery or buds in each section.
4. Immediately replant the pieces at the same level as in their original location and water thoroughly. New growth should begin within a few weeks.

Is This the Right Plant for You?

A LISIANTHUS IS A GOOD CHOICE FOR YOU IF:

• You have pets and want to grow a non-toxic plant.
• You're looking for the challenge of growing a more finicky kind of plant.
• You live in a warm, low-humidity climate.

How to Grow Lisianthus From Seed

Lisanthus grown from seed takes 5 to 6 months to reach mature flowering stage. In zones 7 and lower, start seeds indoors in late fall. In zones 8 and higher, seeds can be directly sown in the garden in late summer for bloom the following spring.

You need trays or small pots, seed starter mix, plastic coverings, grow lights, potting soil, and general-purpose fertilizer.

1. Prep seed trays. Fill trays or small pots with moistened seed starter.
2. Scatter seeds. Scatter seed on the soil surface.
3. Cover trays and keep warm. Cover with plastic wrap and set trays or pots under grow lights. Provide 16 hours of light daily and temperatures between 70°F and 75°F.
4. Move grow lights closer and feed. Once the seeds sprout, remove the plastic and keep grow lights about one inch above the tops of seedlings. Maintain temperature between 60°F and 75°F, feed weekly with a general-purpose fertilizer at half strength, and do not allow soil to dry out.
5. Transplant seedlings. At seven or eight weeks, transplant seedlings into a regular potting mix. Keep the temperature below 75°F, or the seedlings can go into dormancy. Continue with regular watering and fertilizing.
6. Harden off and place outside. At around five months plants should be around 4 inches tall and can be hardened off for transplant into the garden once the danger of frost has passed.
   

Tip

Growing lisianthus from seed is usually left to commercial greenhouse growers and experienced, serious gardeners due to the length of time and amount of care needed. It's easier and more practical for home gardeners to buy mature seedlings from a garden center.

Potting & Repotting Lisianthus

Shorter varieties grow well in containers filled with ordinary potting medium. Colors combine well in mixed containers with dianthus, coreopsis, baby's breath, and snapdragons. In zones where they remain outdoors as perennials, plants require annual repotting, going up one pot size each time.

Plant nursery starts or plugs 3 to 4 inches apart in containers deep enough to accommodate the root ball. Taller varieties require deeper pots and may require staking. Tight placement allows plants to support each other. Terracotta and clay pots are good material choices.

Best Planters for Lisianthus

Lisianthus grows very well in containers. We researched dozens of planters and spoke with garden experts to find the best planters for your garden at a variety of price points.

Overwintering

In zones where lisianthus is perennial, cut back faded flower stalks for continued blooms and reduce feeding during winter months. Zone 7 is transitional where plants may survive if cut back to ground level and covered with a light mulch until spring.

Though challenging, some gardeners find it possible to keep potted lisianthus growing indoors and flowering through winter. The trick is giving them enough bright light, controlled temperatures, and preventing common indoor pests such as mites and fungus gnats. Feed monthly with a weak diluted fertilizer.

Common Pests & Plant Diseases

Fungus gnats are a common pest of lisianthus, and first appear in the seedling stage. Larvae live beneath the soil, feed heavily on roots, and can devastate plants. Avoid overwatering and treat affected plants with a mild insecticide or neem oil. Apply neem oil in cases of spider mite infestation.

Lisianthus are susceptible to plant viruses and stem cankers. Affected plants must be removed and discarded.

How to Get Lisianthus to Bloom

Finicky about growing conditions and care, lisianthus are highly valued as cut flowers with a long vase life.

When Do Lisianthus Bloom

Most lisianthus bloom in June and July with some types putting out a second flush of flowers in September or October. That said, it does depend on your climate and the variety you have.

How Long Do Lisianthus Bloom For?

From when the first bud opens to when the last flower fades, lisianthus blooms for between two and four weeks. Each plant produces multiple flowers.

What Do Lisianthus Flowers Look and Smell Like?

Lisianthus flowers are 5 to 6 inches tall and can be single or double. They look a bit like a rose if it had an exposed center. Lisianthus flowers have no fragrance.

How to Keep Lisianthus Blooming

To keep lisianthus blooming summer through fall, fertilize and water it regularly. Deadheading spent flowers throughout the season will encourage it to keep blooming. You'll also want to set yourself up for success by planting lisianthus in a location that gets lots of sunlight and has well-draining soil.

What to Do After Lisianthus Blooms

In growing zones where lisianthus is perennial, cut plants back to the leaves radiating around the base of the plant after the initial bloom. In zone 7, you can try cutting back and mulching to keep lisianthus alive through the colder season.

Deadheading Lisianthus Flowers

Deadhead lisianthus flowers by cutting flower stems at the point where they emerge from two sets of leaves.

Common Problems With Lisianthus

Lack of full flowering is the most common problem but several other issues make lisianthus challenging to grow.

Plants Topple Over

Long stems are often too thin to support double-bloom varieties. Look for grow-through support rings or grids and other decorative stakes.

Cut Flowers Don't Last

Lisianthus can last up to four weeks as cut flowers. Harvest early in the day using sharp scissors to cut just above the basal leaves. Remove leaves below the waterline and trim stem bottoms before placing in the vase. Refresh water every two to three days.

From: thespruce