How to Grow Lisianthus

Lisianthus is an attractive perennial flower. Often grown as a full sun annual plant, it is a staple of many bridal bouquets and flower arrangements. Ideal for the cut flower garden it can also look attractive when included in a mixed flower bed.

Originating in North America, lisianthus (Eustoma grandiflorum) is an attractive but slow growing plant. Most specimens take around 6 months to mature. Best grown from seed started in late summer this is a project plant. But your efforts will be rewarded the following spring when lance shaped, dark green foliage and showy layered blooms in shades of purple, lilac, pink, cream and white emerge. For something a little different, you can also find red, pale green and yellow flowering cultivars. Some even have ruffled edges and darken as you reach the center.

Perfect for cut flower gardens and containers, lisianthus flowers are a great way to add elegant color and height to a summer garden. Also known as Texas bluebell, prairie gentian or bluebell gentian, this is your complete guide to growing lisianthus.

The rose-like flowers of the lisianthus are an increasingly popular sight in flower gardens. 

Selecting the Right Variety

If you are growing from seed, you will find a range of different lisianthus plants available to you. However, as I have already noted, growing from seed is a long process and not always the easiest way to cultivate new plants. Lisianthus plants take a long time to mature into flowers.This is easiest done in strict greenhouse conditions. Even if germination is successful, the plants may still produce very few flowers. The vast majority of growers find it easier, and more satisfying in this case, to buy plants that are already starting to set bud.

Purchasing young young plants, or transplants ready for planting, from a garden store or plant nursery may not offer you as wide a choice of variety as if you were growing from seed but it is a more reliable option. And you should still be able to create a colorful display.

Most cultivars reach 1 to 3 ft in height and have a spread of 6 to 12 inches. While different varieties can be easily distinguished by their color and size many people try to avoid mixing and matching varieties. Instead growers try to stick to cultivars with a similar height and preference.

If you are growing in containers, select dwarf varieties. Unlike the taller cultivars, which reach 24 to 30 inches, dwarf varieties enjoy a more compact growth habit, making them ideal for containers.

An ideal cottage garden plant, lisianthus makes a great companion plant for other cottage garden favorites such as delphiniums and stock. They also contrast nicely with zinnias and cockscombs.

Popular Lisianthus Varieties

One of the most popular varieties is Flamenco, this is a reliable, double flowering plant. It is also pleasingly heat tolerant. The white flowering Flamenco cultivars with a purple rim are particularly attractive.

Coming in a range of colors, flowers with a colored edge add interest and contrast without being overwhelming.

Balboa is a heavy flowering variety. Each plant produces at least a dozen flowers in various shades of blue. A particularly attractive member of this cultivar flowers in white with a blue edge.

Maurine is a semi-dwarf cultivar making it ideal for pots and smaller spaces. The flowers come in shades of pale blue and purple as well as white.

A distinctive flower, Black Pearl produces deep purple blooms which sit above masses of light green foliage.

For something a little lighter, Arena Gold flowers in an attractive butter-yellow shade while Advantage Cherry Sorbet is a double flowering hybrid. When mature it produces dark rose-pink flowers.

One of the tallest cultivars, Super Magic Champagne reaches heights of 3 ft. It’s soft peach petals, which fade to cream, are a gorgeous addition to the early summer garden. Mariachi Green is another tall cultivar. Reaching up to 2 ft. it is also long lasting, producing distinctive lime-green flowers that are ideal for cut flower arrangements.

On the other end of the scale, Forever Blue is a smaller cultivar, its stalks reach about 10 inches. On top of the stems sit velvety soft violet flowers.

Just as attractive as other cultivars, lime green flowers add something unusual to a garden. 

Where to Plants

The plants are hardy in USDA zones 8 to 10. But they can grow in all zones as an annual. If you are unsure what zone you are growing in, this guide explains everything.

Lisianthus plants thrive in warm, dry spots where the nights are warm. They tolerate heat and some drought well. Conversely these plants struggle in humid and damp climates such as the Pacific Northwest.

Lisianthus plants do best in full sun positions. Consistent light is the key to lots of healthy foliage and flowers. For a full flowering display the plants should receive 6 to 8 hours of light every day. In warmer areas, they will appreciate a little afternoon shade.

The soil should be well draining and pH neutral. Lisianthus plants can’t tolerate acidic soils. Amend the soil with limestone before planting. Lisianthus also likes the soil to stay evenly moist. If it is not well draining root rot can develop. If you are unsure of the makeup of your soil, a soil test kit is a quick way to discover what, if any, amendments you need to make.

While lisianthus happily grows in the ground, the plants are best planted in containers or raised beds. This enables you to ensure that the soil is rich in organic matter. Ensure that you work in lots of leaf mold, compost or manure before planting.

Encourage flowers by planting in a favorable position. 

How to Plant

Transplant young plants as soon as possible to prevent them from becoming pot bound. Allowing them to sit in containers that are too small can stunt growth. In colder areas that experience freezing temperatures, transplant as soon as any danger of frost has passed. In warmer zones you can plant from March onwards. Take the time to fully harden off plants before transplanting.

Especially when hardened off, these transplants are pleasingly frost and cold tolerant. The plants like to use the cool weather growing time to set out a strong root system. This ensures that come the summer they are healthy, established and ready to flower. If the weather turns cold after planting, cover your transplants with a frost blanket or cloche. Covers such as the Valibe Plant Cover form a tunnel over the plants, protecting them from frosts without smothering and flattening any new growth.

To plant, make a hole in the soil large enough to hold the transplant. Carefully remove it from its pot, trying not to disturb the root system. Try to take as much of the soil as possible with the plant. Position the transplant in the middle of the hole. The lowest leaves should sit just above soil level. When the plant is correctly positioned, firm the soil down and water well.

Space transplants 6 to 8 inches apart. This gives them plenty of room to spread and branch out.

Planting in Containers

Lisianthus plants are ideal for container gardens.

The size of the container depends on what type of lisianthus you are growing. Choose shorter varieties that are less likely to require support and staking. Larger varieties such as Forever Blue need pots that are at least 4 to 6 inches deep. This gives the roots plenty of room to spread out and develop. Smaller cultivars can cope in a pot 3 to 4 inches deep. Add well draining potting soil to the pot and plant as described above.

Caring for Lisianthus

Once established, these are easy to care for plants. Just ensure that they have enough light and moisture.

Regularly weed around your plants. After planting lisianthus stays small for a number of months. During this period any foliage that does emerge is typically close to the ground, forming part of a low-growing basal rosette. Allowing aggressive weeds to remain in place runs the risk of them smothering your flowers. Here are some great weeding tools to help keep your soil neat and tidy.

While they may be attractive weeds can smother slow growing flowers. 

Water

Keep the soil moist but not soggy. Let the soil dry out between waterings. This can be difficult to achieve. A soil moisture meter, like the Gouevn Soil Moisture Meter, can help you to work out exactly how wet your soil is.

If in doubt, wait for a few more days before watering. The plants won’t overly suffer by delaying slightly. Conversely, overwatering the plants can encourage rot and fungal disease to form.

Fertilizer

For the plants to fully flourish, lisianthus requires a constant supply of nutrients. This encourages plants to branch and flower. Apply a flower specific fertilizer rich in potassium regularly throughout the growing season. Alternatively, dilute a balanced water-soluble fertilizer down to half its strength and apply every time that you water.

Pruning

As the flowers fade, cut the stems back to the basal rosette of foliage. This helps to encourage a second flowering. Continue to water, weed and fertilize the plants after the first set of flowers fade. New flowers emerge in September.

Remove spent flowers to encourage a second show in early fall. 

Support

Long lisianthus stems bring height and elegance to the garden. But they can struggle to support the flowers, particularly double blooms. A bamboo stick provides a little support and can easily blend into a flower bed. These are best installed when planting.

Preventing and Solving Common Problems

If planted in a favorable position and cared for correctly, these are largely problem free plants.

Fungus gnats can target lisianthus throughout their lives, first targeting the plants when they are young and growing in a greenhouse. Try not to overwater the plants. Treat infestations with some neem oil. Continue to apply to the leaves until all signs of infestation have disappeared.

Leaf miners, thrips and aphids can all target the foliage of the plant. Regularly check for signs of infestation.

Finally, you will also need to protect developing seedlings and young plants from slugs and snails.

Growing From Seed

As I have already noted, this is a time consuming process. You need around 6 months of growing time before flowers form.

Start the seeds undercover. Lisianthus seeds are fine and hard to handle so are often pelleted to make handling easier. Sow from mid-December to January, around 16 to 22 weeks before the average last frost date in pots or trays filled with a good seed starter mix.

Moisten the soil before spreading the seeds on top. There is no need to cover the seeds. Place the trays in a propagator or cover with a plastic lid. Seeds need 16 hours of light every day in order to germinate. Artificial light, such as grow lights, can be used if you can’t provide enough natural light.

Germination occurs within 2 weeks. During this period, try to keep the temperature between 70 and 75 ℉. Be careful not to let the temperature exceed 75 ℉. Too much heat can cause seedlings to become dormant and it can take a long time to wake them up and start growing again.

Once seedlings emerge, remove the covers. Nighttime temperatures can now be allowed to fall to 60 to 65 ℉. Don’t allow it to get much cooler than this.

As the seedlings grow, keep the medium moist to the touch. Allow fresh air to circulate freely around the developing plants. This helps to prevent damping off and mildew from forming. You can also apply a calcium based fertilizer or general purpose fertilizer diluted to half strength once a week. Continue to do this until roots and cotyledons, or first leaves, develop.

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Transplant into small pots after 7 to 8 weeks of steady growth or when 2 to 3 sets of true leaves have formed. When transplanting use a small spoon to scoop out as much of the soil and roots as possible. This ensures that the sensitive roots are unlikely to be disturbed. Plant so that the seedlings’ bottom leaves are just above the level of the potting soil. Transplanting into biodegradable peat pots, such as Delxo Peat Pots means that you can later plant the seedling still in the pot in the ground. As the plant grows the pot degrades and breaks down. This enables you to transplant sensitive seedlings without disturbing the root system.

At this stage, the seedlings are now less prone to rosetting, or entering the dormant period so the temperature can be allowed to slightly exceed 75 ℉.

Bottom water the pots, increasing the fertilizer to half strength with every watering. Allow the medium to dry out slightly between waterings.

When the seedlings are 3 to 4 inches tall and have 4 sets of true leaves, usually in late May or early June begin hardening them off. Once hardened off, transplant into their final position.

Lisianthus for Cut Flowers

Lisianthus mask great, long lasting cut flowers. To get the most out of the blooms, cut early in the day as the first buds start to open. Use a scissors or sharp knife to cut the stem at the base.

Remove any leaves below the water level and recut the stems as you arrange them. Change the water every 2 or 3 days.

Elegant and attractive, Lisianthus is a versatile member of the flower garden. 

Similar to roses, the slender leaves and soft blooms of the lisianthus flower make it an attractive member of the summer flower garden. Their long lasting blooms, most flowers open for around 4 weeks, make for a fabulous addition to the flowerbed. As a cut flower lisianthus lasts well in a vase or can be used as the centerpiece of a bouquet. With such versatility, it is easy to see why these flowers are increasing in popularity. Elegant and easy to care for, why not add some lisianthus to your garden this summer?