Lisianthus is a warm-zone perennial flower (often grown as an annual) that has gained a reputation of being somewhat finicky and difficult to grow. In reality, if you just learn the needs of lisianthus and attend to them, you will be able to successfully grow a flower that is in great demand for bridal bouquets and other special-occasion flower arrangements.
Native to North America, lisianthus will grow slowly, often reaching maturity in around five to six months. The plant is best grown from seed starting in late summer and will come to full bloom by the following spring when it erupts in fluttery, layered blooms. 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.
|Botanical Name||Eustoma grandiflorum|
|Common Name||Lisianthus, prairie gentian, bluebell gentian|
|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|
|Bloom Time||Summer, fall|
|Flower Color||Purple, pink, white|
|Hardiness Zones||8–10 (USDA)|
|Native Area||North America|
Lisianthus will grow in all zones as an annual plant, but you can expect better performance in areas with mild summers. While you can grow lisianthus from seed, doing so is not advisable for beginner gardeners since they take a very long time to mature into blooming-sized plants unless cultivated under strictly maintained greenhouse conditions.
Your best bet is to buy lisianthus plants with buds or flowers already emerging, as even greenhouse growers can sometimes produce plants that favor foliage over flowers. Otherwise, growing lisianthus isn't very difficult so long as you provide it with enough light and moisture.
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 stress 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. 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. If soil testing reveals acidic soil, you can add limestone to your soil mixture to increase its alkalinity.
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.
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. They do not mind hot conditions and can even tolerate a bit of drought, but are not tolerant of humidity and do 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.
There are many different varietals of lisianthus, most distinguished by their color and size. The delicate appearance of lisianthus plants makes them the perfect addition to a cottage garden alongside other English classics like scented stock and delphiniums.
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.
- ‘Balboa’: This varietal 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 varietal 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.
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 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.
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.
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 larva are, who live beneath the soil and feed heavily on roots, devastating your plants.
To rid your plant of fungus gnats, focus on not overwatering (or waterlogging) the plant. You can also treat the plant with a mild insecticide or neem oil until all signs of an infestation have gone.