Digitalis purpurea‘Camelot’

Digitalis purpurea 'Camelot' is the first F1 hybrid on the market and offers many desirable characteristics to growers and consumers alike. Growers will appreciate its high germination rate, uniform growth and more reliable first-year flowering. Consumers enjoy a great bloomer with huge tubular florets that have speckled throats, consistent landscape performance throughout much of the country, strong stems, and four colors: cream, lavender, rose and white.

Camelot was introduced into the market in 2003. Like many digitalis cultivars, it is not a true perennial, and in most locations throughout USDA Hardiness Zones 5-9, it should be treated as a biennial. Digitalis grows best in partial shade and can tolerate full sun, provided it is not allowed to dry out. Camelot will flower reliably the first year from seed and will bloom heavily the second year. When in bloom, it reaches 3-4 feet high with a spread of 24-30 inches. It forms many sturdy, high-quality secondary flower spikes, extending the bloom time to over four weeks in many instances.

Propagation

Camelot is propagated by seed. Due to the small size of the seed, it has been pelleted, making it easier to handle and more suited for automated seeders. Do not cover the seed when sowing because light is necessary for germination to occur. It is recommended to place the plug flats into a germination chamber or greenhouse, maintaining soil temperatures of 65-70¡ F with high humidity until seeds have germinated. With these conditions, germination will usually occur in 7-10 days. Placing the plug flats in a germination chamber helps to improve the germination rate and decreases the overall germination time but is not necessary to successfully produce Camelot from seed. It takes 7-9 weeks from sowing for 72-cell plug flats to reach transplantable size.

Production

Camelot is most suitable for 1-gal. or larger container sizes. It performs best when grown in a moist, well-drained medium with a slightly acidic pH of 5.8-6.2. It is a light to moderate feeder and performs best when either a constant liquid fertilization program, feeding at rates of 75-100 ppm nitrate, is used or a controlled-release fertilizer is incorporated at a rate equivalent to 1 lb. of nitrogen per yard of growing medium. Digitalis prefers to be kept moist but not consistently wet. I recommend watering thoroughly as needed, allowing the soil to dry slightly between waterings.

The highest quality plants are achieved when they are grown at cool temperatures. Temperatures above 73¡ F result in plants that are taller, have fewer flower spikes and are generally lower quality. I recommend growers produce digitalis at cool to moderate temperatures within the range of 60-68¡ F.

Camelot is a tall plant when produced in containers and marketed in bloom. To maintain plant quality, commercial growers will have to combine both cultural and chemical methods of controlling plant height. The first approach to reducing unnecessary plant stretch during crop production is to provide adequate spacing or to withhold water and nutrients. Additional height control may be necessary, particularly as the flower stalk begins to elongate. When necessary, apply plant growth regulators. A-Rest (SePRO), B-Nine (Crompton/Uniroyal) and Su-magic (Valent) have been shown to be effective on this variety. I recommend growers start foliar applications using a local equivalent of the following Northern rates: A-Rest at 25 ppm, B-Nine at 2,500 ppm and Sumagic at 5 ppm, adjusting the rate to their geographic location and season. Two applications seven days apart should provide adequate control.

Aphids are the most troublesome insect pests of digitalis. Unless preventative programs have been put into place, I don't recall observing an aphid-free crop of foxglove. I usually apply a preventative drench application of Marathon 60WP (Olympic) to ensure the absence of aphids for the duration of the production cycle. Botrytis is likely to occur late in the crop cycle once the canopy closes in and plants begin to bloom. Spent flowers will generally fall into the foliage where Botrytis is most likely to arise. Botrytis can usually be prevented or reduced by providing adequate spacing, good air circulation at all times, maintaining a relative humidity below 70 percent, selling plants when the lower flower buds begin to open and, if necessary, implementing a preventative fungicide spray program using products such as Decree (SePRO) and Daconil (Syngenta).

Forcing

Successful forcing involves following a few key guidelines. Camelot does not have a juvenility requirement for flowering but typically produces 8-12 leaves before flowering. These leaves will form during crop development; growers don't have to worry about satisfying a juvenility requirement prior to providing other treatments. Camelot likes cold temperatures but will flower with or without a cold treatment. The best results are achieved when it is cooled for at least 10 weeks prior to forcing, this provides more uniformity and faster flowering. Camelot is a quantitative long-day plant, which flowers quicker under long-day conditions as compared to short days. Regardless of the daylength, the light level is very important to provide uniform flowering and high-quality plants. When producing digitalis during times of the year when the light levels are naturally low, it is beneficial to provide supplemental lighting using high-pressure sodium lamps that ensure 16 hours of light each day. From the start of forcing it will take about 11 weeks to reach flowering at 60¡ F or eight weeks at 68¡ F.

Availability

Camelot seed bred by Goldsmith Seeds is available as individual colors (cream, lavender, rose and white) or as a mixture from various seed distributors. Finished plugs can be purchased from many reputable perennial plug producers.

Paul Pilon is head grower at Sawyer Nursery, Hudsonville, Mich. He can be reached by E-mail at paul@perennial-solutions.com.