Lisianthus flowers have gained a reputation, somewhat unfairly, of being finicky and difficult to grow. But in reality, if you just learn the needs of the 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.
Lisianthus flowers are most commonly available in cool tones, but you may occasionally see yellow or carmine-red flowering plants for sale. Single or double 3-inch blooms (most popular with florists) grow in every variation of pink and purple. The flowers are attractive in bud as well as in full bloom. Plants usually yield several blooms on each stem. The flower's foliage is dark green and lance-shaped.
- Botanical Name: Eustoma grandiflorum
- Common Name: Prairie gentian, Texas bluebell, Eustoma, Lisianthus
- Plant Type: Herbaceous annual
- Mature Size: 6 to 40 inches tall and up to 14 inches wide
- Sun Exposure: Full sun
- Soil Type: Loamy
- Soil pH: 6.5 to 7.0
- Bloom Time: Spring
- Flower Color: Purple, pink
- Hardiness Zones: All (strictly an annual flower)
- Native Area: Southern U.S., Mexico, northern South America
How to Grow Lisianthus
Lisianthus will grow in all zones as an annual, but you can expect better performance in areas with mild summers. While you can grow the plants from seed, they aren’t for beginners, and the they take a very long time to mature into blooming-sized plants when they aren’t cultivated under strictly maintained greenhouse conditions. Your best bet is to buy plants with buds or flowers already emerging, as even greenhouse growers may sometimes flub and produce plants that favor foliage over flowers.
Plant lisianthus in full sun. If you live in an area with very hot summers, the plants will benefit from some afternoon shade.
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 an acidic soil, you can add limestone to increase the alkalinity.
Keep lisianthus plants moist, but never soggy. Overwatering encourages the development of fungal diseases. A drip irrigation system is ideal for giving your plants water right where they need it, at the roots.
Temperature and Humidity
Lisianthus are heat-loving plants that are native to the prairie lands of the Southern U.S. and Mexico, where the days are relatively dry and the summer nights are warm. They do not do well in damp climates with limited sun, such as the Pacific Northwest. The flowers can tolerate normal humidity in most growing regions but do not like frequent rain.
Lisianthus flowers like a constant nutrient stream to produce well-branched plants with abundant blossoms. Choose a flower fertilizer with 1 1/2 times the amount of potassium as nitrogen, and apply it according to package directions throughout the growing season.
If you've gone to all of the bother of growing your lisianthus divas and had a successful flush of blooms in the spring, chances are good that you can coax a second act from the plants, come fall.
Cut the stems back to the basal rosette of foliage after the plants' initial bloom. Then, give your plants all the pampering they crave: This means thorough weeding, regular irrigation, and 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.
Lisianthus flowers expand the range of early-season bloomers, adding to pansies, snapdragons, and violets in the spring landscape. Buy mature plants as soon as they are available to provide blooms while you wait for your cosmos and zinnia seeds to grow.
Grow the dwarf varieties of lisianthus in containers for your deck and patio. The delicate appearance of lisianthus plants seems at home in the 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’ series: Three dozen flowers per plant are produced on average in shades of blue.
- ‘Flamenco’ series: Although gardeners seem to prefer the double flowers over the single flowers, the heat-tolerance and ability to grow without staking make this single-blossoming type worth a try.
- ‘Maurine’ series: This type is a semi-dwarf, heat-tolerant variety.
Fungus gnats are one of the most common pests of lisianthus and can travel with the plants from early in the greenhouse stage. The flying adults aren’t the problem; the larval stage beneath the soil feed heavily on roots and will devastate your plants. Organic gardeners can use Gnatrol, a biological agent, to control the gnats. Effective chemical controls include Pyrethrum, Diazinon, and Permethrin products.