August 2006

Crop Culture Report: Dianthus F1 Polar Series By Julia Paul

In these times of ever-increasing energy costs, growers are looking for crops to fill their benches without emptying their wallets. The quest by retailers and consumers for colorful and hardy season extenders has been an ongoing one. Dianthus chinensis x barbatus F1 Polar series is new for 2006-2007. It is bred to flower early and bloom all season long.

Under cool growing conditions, Polar should flower one week earlier than Telstar, which allows growers to finish crops outdoors or in open-roof greenhouses to save on heating expenses. Polar can be turned relatively fast under these conditions for early season sales.

Uniformity within this series makes for easier production scheduling. In late spring/early summer, time from sowing to flowering is 10-11 weeks. Late summer/winter timing is 12-13 weeks from sowing to flowering. Polar can work well alongside other early-spring, cool crops such as linaria, kale, osteospermum, pansy, snapdragon and erysimum.

Plant Characteristics

Polar plants have a good branching habit, particularly under cooler temperatures, and reach a compact height of only 8-12 inches. They are bred to bloom all season long with flowers slightly larger than the dianthus F1 Telstar series. Even though Polar was bred for earliness under cool culture, it can also do well under warm growing conditions.

The Polar series has seven colors plus a formula mix made up of all the colors. Vibrant, solid colors of Coral, Crimson, Purple and Rose are available along with Pink Blush, which has variegated flowers ranging from light to dark pink. The series also offers Purple Picotee and Red Picotee bicolors.

Polar is bred to provide a colorful display in the home garden as well as commercial landscapes. While the plants are robust, they should maintain their shape and balance and have a spicy fragrance.

Propagation

Sow Polar seeds in a 288-cell plug tray with a well-drained medium. A soil pH of 6.2-6.8 is recommended. Germinate seeds at 70-75¡ F and provide moderate, even moisture; 95- to 97-percent relative humidity is acceptable. Emergence normally occurs in 3-5 days. The EC from emergence to cotyledon expansion should be about .5-.75.

Fertilize beginning at Stage 3 with 50-ppm nitrogen and continue a fertilization program until the plugs are finished. The EC from cotyledon expansion to plug finish is recommended at about .75. Plug finish time is 5-6 weeks in a 288-cell plug tray.

Plugs should be transplanted 30-40 days after sowing into the finish container; optimum temperatures for finishing are 50-60¡ F days and 40-50¡ F nights.

Growing On

For early spring growing, temperatures may be kept cool but no lower than 40¡ F at night. Polar's earliness is most evident under cooler culture. Polar also performs well under standard growing temperatures of 60-75¡ F days and 50-60¡ F nights.

Once established, apply a calcium-based fertilizer or 15-5-15 at 150 ppm 1-2 times per week. As with all dianthus, adequate calcium is required. EC for finishing is recommended at about .75-1.0.

Plants will flower 80-100 days from sowing, depending on the growing temperature. Polar finishes well in everything from cell packs to 5-inch pots as well as multiples in 6-inch pots and 1-gal. containers.

While having the same susceptibility to common diseases such as Alternaria leaf spot, Pythium, Fusarium wilt, bacterial wilt, bacterial spot and Rhizoctonia as all other dianthus, Polar exhibits the same Phytophthora resistance as the Telstar series. Common dianthus pests include thrips, aphids, mites, cutworms and whiteflies.