October 2009 Culture

Saxifraga arendsii Touran Series By Paul Pilon

Saxifraga arendsii is a cool-season alpine perennial that provides an abundance of bloom in the early spring. The Touran series is a recent introduction from Syngenta and offers a nice compact habit combined with an abundance of flowers. The Touran series consists of four cultivars: Deep Red, Neon Rose, Scarlet and White. These cultivars bloom uniformly with impressive flower power for an extended period of time. With its early flowering, flower power and extended bloom time, the Touran series can easily be marketed alongside annuals in the early spring.

The flowers are held nicely above deeply dissected succulent foliage in the early spring. The compact mounds of color reach 4-6 inches tall and 10-12 inches wide at maturity. This cool-season perennial is best suited for production in Northern locations and is most commonly grown in USDA Hardiness Zones 3 to 7. This plant can be produced in Southern locations but performs more as an spring annual as it does not tolerate the extreme summer heat in these locations.

Other benefits for commercial growers are that they do not require pinching and can be grown with cool production temperatures. Saxifraga is commonly used in small containers, combination planters, and in small mass or border plantings. With its container and garden performance, ease of production and flower power, the Touran series is an impressive and reliable performer that will complement any commercial perennial program.

Propagation

The Touran series cultivars are vegetatively propagated from tip cuttings by licensed propagators. A U.S. Plant Patent has been applied for; propagation without permission of the applicant is illegal. Before sticking the unrooted cuttings, moisten the rooting medium in the plug flat. Rooting compounds are optional as saxifraga will root well without using them.

Place the cuttings under a low misting regime for the first seven to 10 days of propagation. When possible, propagate under high humidity levels (90 percent relative humidity) with minimal misting. At seven to 10 days after sticking, apply water-soluble fertilizers using 75- to 100-ppm nitrogen at each irrigation beginning. The misting can gradually be reduced as the cuttings form callus and root primordia. Remove the cuttings from the mist once they are rooted (two to three weeks).

It is recommended to maintain soil temperatures of 70-74¡ F for the first 10 to 14 days until they have developed roots. After roots are present, the media temperatures can be reduced to 64-68¡ F. Liners take six to seven weeks from sticking to become fully rooted and ready for transplanting.

Production

The Touran series is most commonly produced in small container sizes (5-inch or smaller) with a single plug planted in the center of the pot. When transplanting, the growing medium should be even with the top of the plug. Saxifraga performs best when they are grown with slightly dry to average moisture regimes using a well-drained medium with a slightly acidic pH of 5.5-6.5. When irrigation is necessary, water them thoroughly then allow the soil to dry moderately between irrigations.

Saxifraga are light feeders. Nutrients are commonly delivered using water-soluble sources, providing 50 to 75 ppm using a constant liquid fertilizer program or 150 ppm as needed. Providing high or luxury fertility levels will cause them to appear lush, lead to excessive stem elongation and may delay flowering.

Given the Touran series' compact growth habit, it is usually not necessary to control plant height. It can be controlled effectively with water management, avoiding high nutrient levels, and providing adequate spacing between the plants.

Insects and Diseases

There are only a few problems with insects or diseases that growers are likely to experience. Aphids are the insect pest most likely to be problematic for growers.

Occasionally, growers might observe powdery mildew and rust attacking saxifraga, but the most common disease is Botrytis, which is likely to occur late in the crop cycle once the canopy closes in, as plants begin to bloom, or just after flowering. In most cases, fungal pathogens can be prevented or reduced by providing adequate spacing, good air circulation and relative humidity below 70 percent, and selling plants just as the flower buds begin to open. Preventive fungicide applications can be made using the appropriate fungicides when optimal conditions for these diseases arise.

Insects and diseases can be detected with routine crop monitoring; control strategies may not be necessary unless scouting activities indicate actions should be taken.

Forcing

The Touran series is easy to force into bloom and is most commonly produced for early spring sales. They have an obligate cold requirement for flowering. Bulk them in the final container size for at least six weeks before providing the necessary cold treatment; transplanting vernalized plugs will result in small plants with few flowers. Provide a minimum of six to eight weeks at 35-44¡ F to complete vernalization of plants that have been adequately bulked up. They are day-neutral perennials and will flower under any photoperiod following the cold treatment. Saxifraga can be forced into bloom under natural day lengths, as the length of the photoperiod has no effect on the time to flower or the number of blooms produced. The time to flower after vernalization is a function of temperature; at 60-65¡ F they will flower in five to six weeks. They can also be grown in unheated structures or in outside production facilities for slightly later sales periods.

Availability

Please contact your Syngenta Horticulture Services (www.greendemon.net) representative for availability of unrooted cuttings and rooted liners.