October 2004

Gaura lindheimeriBallerina By Paul Pilon

Gaura lindheimeri has become known as a plant that offers growers and gardeners great versatility and resiliency throughout a wide range of the country. Due to the popularity of perennials and increased interest in gaura, breeders across the world have been working diligently to improve certain characteristics of this plant species. The Ballerina series is the result of that breeding work.

'Ballerina Blush' has pale pink blooms, and 'Ballerina Rose' has rose pink flowers. The flowers resemble small, charming butterflies whirling around on slender stalks. Unlike some of the earlier commercially grown gaura cultivars, which reached 3-4 feet tall, the Ballerina series grows to a manageable 12-18 inches when blooming. Plants bloom consistently throughout the summer, especially when the spent flower spikes are removed. These characteristics lend themselves well to perennial-forcing programs, container production, mass plantings and use as accent plants.

Gaura lindheimeri is native to North America, originating in Texas and Mexico. This cultivar, like other gaura varieties, prefers full sun and can tolerate a great deal of heat and humidity. The Ballerina series performs well across a wide portion of the United States, throughout USDA Hardiness Zones 5-9 and AHS Heat Zones 9-5.

Propagation

Ballerina is vegetatively propagated by tip cuttings from licensed propagators. Since a plant patent is being sought, unlicensed propagation of this cultivar is prohibited. Growers purchasing unrooted cuttings from licensed propagators may root only those cuttings.

Cuttings can be successfully rooted by sticking them directly into a well-drained growing medium or other rooting medium such as Oasis cubes or Fertiss propagation plugs. Many growers dip the unrooted cuttings into a rooting hormone such as a solution of indolebutyric acid (IBA) at rates between 500 and 1,000 ppm. The rooting compound is not essential for successful rooting but does tend to provide a slightly higher rooting percentage and also reduces the rooting time.

Cuttings should be placed under low misting regimes for about the first week of propagation. Increasing the misting interval (number of mists per day) or extending the number of days misting is provided will both usually result in some plant loss. The average rooting time for Ballerina is 4-6 weeks with soil temperatures ç ranging from 68 to 74¡ F. For best results, the air temperature during rooting should be maintained above 50¡ F and below 80¡ F.

Production

Ballerina is adapted to well-drained soils and performs well in most soilless commercial mediums. It is a moderate feeder and performs best when the pH is maintained at 5.8-6.5. Growers using constant liquid fertilization programs should feed using rates of 50-100 ppm nitrate. Many growers incorporate controlled-release fertilizers at the time of planting, using a rate equivalent to 1 lb. of nitrogen per yard of growing medium.

Gaura generally prefer to be grown under slightly dry irrigation regimes but will also perform well under more normal watering scenarios. When irrigation is necessary, I recommend watering thoroughly then allowing the soil to dry moderately between waterings.

Ballerina is relatively insect and disease free. However, aphids, leafminers and whiteflies may occasionally become problematic. Of these insect pests, aphids are the most prevalent. I recommend implementing preventative monthly spray applications of systemic chemicals such as Endeavor (Syngenta), Flagship (Syngenta) or Marathon II (Olympic Horticultural Products). Another reason I recommend using a preventative program such as the one described above is that one application will control aphids and prevent the occurrence of whiteflies as well.

Botrytis is occasionally a problem on the lower foliage where air movement is limited and the foliage often stays wet after irrigation for extended periods of time. To control Botrytis it is best to manage the environment by providing proper plant spacing and adequate air movement. Watering early in the day will limit the length of time the foliage remains wet. Implementing a preventative spray program using chemicals such as Decree (SePRO) or Daconil (Syngenta) will also greatly reduce the occurrence of this disease.

Root rots from such pathogens as Pythium and Phytopthora are also observed occasionally by growers. Root rots usually occur when improper cultural conditions are present. For example, improper drainage and over watering are the most common conditions that promote these diseases. Other cases could result when injury occurs to the roots from high salt levels in the root zone or some other type of stress. Providing and managing the proper environment around the roots are the most important methods growers can use to prevent root rot diseases. If chemical controls are necessary, Banrot (Scotts Company) and Subdue Maxx (Syngenta) are both effective at controlling Pythium and Phytopthora.

Controlling plant height is not usually necessary when producing Ballerina under greenhouse conditions. Providing adequate spacing between plants will reduce plant stretch caused by competition. Under certain growing conditions or under high plant densities it may be necessary to use chemical plant growth regulators. In the Northern parts of the country, I would recommend applying Sumagic (Valent USA) at 5 ppm or B-Nine (Crompton/Uniroyal) at 2,500 ppm. Applying 1-2 applications seven days apart should provide adequate height control. To produce a fuller plant, it may be beneficial to pinch prior to or shortly after planting.

Forcing

Forcing Ballerina into bloom out of season is relatively easy by following a few guidelines. I recommend growers bulk gaura for 4-6 weeks prior to providing a cold treatment (vernalization). It may be worthwhile to trim or pinch them back at the beginning of the bulking period to promote lateral branching, which will provide fuller plants with more flowers. Providing a cold treatment for a period of six weeks at temperatures of 35-44¡ F will decrease the time to flower, increase the flower number and greatly improve overall plant quality and appearance. Gaura will flower without a cold treatment, but the overall flower number and quality attributes will be reduced.

Gaura is a facultative long-day plant, which essentially means it will flower under any photoperiod but will flower faster under long-day conditions. When forcing during periods of the year when the natural daylength is less than 13 hours, I highly recommend growers provide long-day conditions using a 4-hour night interruption between 10 p.m. and 2 a.m.

The time it takes for gaura to bloom is a function of temperature. Ballerina grown at 65¡ F will take approximately seven weeks to reach flowering, while plants grown at 75¡ F will flower in five weeks. Gaura grown under warmer temperatures will have smaller flowers and be of lesser quality than plants grown under cooler temperature regimes. The best flower size is achieved by growing at temperatures averaging 65¡ F.

Availability

The Ballerina series is brought to the marketplace by Ball FloraPlant. Unrooted cuttings are available only from Ball Seed Company. Rooted liners from licensed propagators and finished containers may be purchased from many reputable companies across the country.