What's New with Lisianthus?

"I am convinced that the florist business resta entirely in our hands. In no other part of the world is there a better chance to develop this industry than here, or a better market." Lisianthus is a long-time favorite of any true flower enthusiast. Today the species is making a comeback and regaining popularity with an array of exciting new improvements in color and bloom size. Doublini, for example, is a new series that offers 1½―2 inch extra-small, rose-shaped double flowers and is available in three striking colors: blue, rose pink and white. Eustoma grandiflorum, commonly known as lisianthus, is native to the wet prairies of Nebraska, Colorado, Texas and northern Mexico. Although lisianthus is native to North America, it is highly prized by the Japanese who initially commercialized it. Today, lisianthus is available year-round in a wide range of colors (including blue) and various flower forms from fully double to single types. The growth and development of lisianthus requires 5-6 months and can be divided into two distinct periods: seedling stage and finishing. Seedling Stage Lisianthus seeds are sold pelleted for ease of sowing, and most often produced in either a 392 or 288 deep plug tray. Plug production time ranges from 8-11 weeks, depending on conditions. Select a medium with good drainage and pH of 6.5-7.0 in order to supply sufficient calcium. The optimum germination temperature is 68-72F /20-22C and pre-cooling* is becoming standard practice. Lisianthus is sensitive to rosetting (induced dormancy) from stress or extended periods of temperatures over 78F/26C. A night temperature of 60-62F/16-17C is recommended. If the day temperature is excessive (>78F/26C), lower the night temperature to (50-55F/10-13C) to provide a lower average 24-hour temperature to prevent rosetting. A light cover of medium vermiculite works well to maintain even moisture and dissolve the pellet. The use of capillary mats is another option to maintain even moisture and provides conditions similar to what is found in nature. *After sowing, plug trays are placed in a cooler uncovered at 50F/10C for 3-4 weeks. Pre-cooling promotes a rapid and uniform germination. After removal from the cooler the trays are lightly covered with vermiculite, then germinated following standard protocol. Initial growth is slow and seedlings benefit from a calcium nitrate-based feed at 100-150 ppm N. Light levels should range between 3,000-3,500 foot candles/32,000-38,000 lux. If possible, provide short days (< 12 hours) during the seedling stage to promote vegetative growth and maximize stem length following transplanting. Seedlings are ready for transplanting when four true leaves are present.

Finishing Stage

Select a cut flower bed with a pH of 6.8-7.2, high in organic matter with good drainage.  Work the bed to a depth of 12 inches to promote deep rooting. Transplant seedlings on time (prior to root wrap) for optimum establishment. Set the seedling “slightly high” in the bed to prevent stem rot (rhizoctonia). A spacing of 4 x 6 inches/10 x 15 cm works well and allows for sufficient air movement. Some growers set plants tighter and then leave the center row(s) empty. Following transplanting, apply water overhead for a few weeks or until the roots penetrate into the outer soil.  Once established apply water via drip irrigation to keep the foliage dry. In areas of low humidity, some growers bury the irrigation lines 3-4 inches below the soil surface, which keeps the surface dry (minimizes botrytis) and promotes deeper root penetration.Fertilize as needed to maintain an EC of 1.2-1.4 mmhos (2:1 dilution). Prior to visible bud, water and fertilize regularly. Then, tone the plants as they mature and flower buds appear by increasing the time between irrigations. Lisianthus develops and flowers based on a combination of temperature, light, and photoperiod. A minimum soil temperature of 55F/13C is necessary for active growth. Once plants are established, higher temperatures, stronger light intensity, and longer photoperiods accelerate development.
For this reason lisianthus is into three groups based on their response to the above factors, similar to forcing snapdragons. The use of high intensity lights and temperature manipulation allows growers to economically force lisianthus year-round in cooler, high latitude areas during the winter months. In general, plants begin to flower 16 weeks following transplant under natural conditions.  For the best quality cut flowers reduce the temperature (< 75F/24C) and light intensity to 1,500-2,000 foot candles/16,000-22,000 lux. Ultraviolet light intensifies the flower color. Cut stems when one or two flowers are open and place in tepid (68F/20C) water and store at 39F/4C.  A flower preservative is strongly recommended and increases vase life by 40-50%. Consumers are attracted to lisianthus because of the wide color range, unique flower forms, and long vase life.  An American native offering a simple beauty with great sophistication.
The above information is intended only as a guide and is based on general growing practices. 
Results may vary based on climate and local conditions. 

Bob Croft

Bob Croft is a 22-year veteran of Sakata Seed America, working in technical support and trials.
Bob supports growers with culture information and feedback on trials. Contact him at [email protected]