October 2014 Culture

Perennial Solutions: Scabiosa columbaria Giga Series By Paul Pilon

The Giga series of scabiosa from Green Fuse Botanicals is a great example of the expression "Great things come in small packages." After all, the plants form compact 6- to 9-inch tall clumps of gray-green foliage which produces an abundance of exceptionally large 3-inch blooms.

The Giga series currently consists of two colors: 'Blue' and 'Purple' and a third color, 'Pink', is expected to be available for the 2015/16 growing season. These cultivars produce an impressive display of large 3-inch blooms; that's one inch larger than other scabiosa cultivars on the market. The flowers first appear in mid spring and continue throughout the summer. The plants grow 12- to 15-inches wide and 12 to 18 inches in height when blooming.

Pincushion flower can be grown throughout much of the country, USDA Hardiness Zones 4 to 10. They perform best in locations with good drainage and full sun; it is best to put them in locations with light shade in the Deep South and West. Scabiosa is commonly used in containers, perennial borders or as a cut flower and is great for attracting butterflies into the garden. With its container and garden performance, ease of production and flower power, the Giga series are impressive and will complement any commercial perennial program.

Propagation

The Giga cultivars are vegetatively propagated from tip cuttings. The cuttings should be placed under a low misting regimen for the first seven to 10 days of propagation. When possible, it is usually best to propagate under high humidity levels (90-percent relative humidity) with minimal misting. At seven to 10 days after sticking, it is beneficial to apply water-soluble fertilizers using 75- to 100-ppm nitrogen at each irrigation. The misting can gradually be reduced as the cuttings begin to develop roots. Remove the cuttings from the mist altogether once they are rooted and do not flag during the heat of the day. They will root in approximately three weeks with soil temperatures ranging from 68 to 72¡ F. Liners take approximately five to seven weeks from sticking to become fully rooted and ready for transplanting.

Production

Scabiosa Giga is suitable for production in 4- to 6-inch containers and can be grown using one plug planted in the center of each pot. When transplanting, the growing medium of the pot should be even with the top of the plug. Take care as to not bury the crown; planting them too deeply lengthens the establishment time, reduces plant vigor and increases the likelihood of crown rots. They perform best when grown in a moist, but well-drained growing mix; this is of
particular importance during the overwintering period. Giga branches freely and does not require pinching.

Scabiosa have a moderate fertility requirement. Nutrients can be delivered using water-soluble sources, providing 100 to 125 ppm using a constant liquid fertilizer program or 200 ppm as needed. To help maintain good foliage coloration, it is beneficial to use nutrient sources containing micronutrients. Controlled release fertilizers can also be incorporated into the growing mix using low to medium rates prior to planting. It is best to maintain the pH between 6.0 and 6.4 during production. When irrigation is necessary, water them thoroughly then allow the soil to dry slightly between irrigations.

The height of scabiosa Giga can often be maintained by not over fertilizing; the delivery of luxury or excessive nutrients will lead to stem elongation. Additionally, growing them with an adequate amount of space between the plants will significantly reduce plant stretch. If height control is required, several plant growth regulators (PGRs) are effective at controlling the growth of scabiosa. If PGRs are necessary, I recommend making spray applications of 2,500-ppm daminozide (B-Nine or Dazide), 5-ppm uniconazole (Concise or Sumagic) or 30-ppm paclobutrazol (Bonzi, Paczol, or Piccolo). One or two applications of PGRs applied seven to 10 days apart should provide adequate height control.

Insects and Diseases

Occasionally, aphids, slugs, two spotted spider mites and whiteflies may be observed feeding on scabiosa. The injury to the plants is usually minimal. Of these insect pests, spider mites are the most troublesome and growers often implement preventative strategies to
prevent their occurrence. The primary diseases growers should watch for are Botrytis, crown/root rots (Pythium and Rhizoctonia) and powdery mildew. Growing them at an appropriate spacing as well as avoiding wet growing conditions will go a long way at preventing these diseases from occurring. Many growers have found it beneficial to apply preventative fungicide drenches for controlling crown and root rots after transplanting and again prior to overwintering. With routine weekly scouting, the presence of insects and diseases can be detected early and the appropriate management strategies can be implemented to manage any problems before they escalate.

Scheduling and Temperature

It is relatively easy to produce flowering plants of the Giga series. Scabiosa are typically grown for sales in the early spring; however, they are also well suited for fall sales. Pincushion flowers are classified as both cold and long day beneficial plants; however, they flower quite profusely without vernalization and can be grown under natural day lengths. For these reasons, Scabiosa Giga is part of the Green Fuse Botanicals First Light Perennials program, which consists of other easy-to-grow first-year flowering perennials.

There are two common approaches to producing flowering containers of Giga for spring sales. The first method entails planting unvernalized plugs into the final container during early to mid fall, allowing the plants to bulk up slightly, vernalizing them and forcing them to bloom in the early spring using low production temperatures of 60 to 65¡ F for six to seven weeks. This practice is particularly beneficial when growing scabiosa in large container sizes. The second strategy involves transplanting vernalized or unvernalized liners into the final containers during the late winter and growing them at 60 to 65¡ F. Cold-treated plants will flower slightly faster than plants which did not receive vernalization and are often used for producing small container sizes. At these temperatures, vernalized plants will flower in as little as six weeks and non-vernalized plants will bloom in eight to nine weeks. Scabiosa Giga can also be produced for fall sales using the second production strategy.

Availability

Contact your Henry F. Michell's Co. (www.michells.com) representative to determine your options for purchasing unrooted cuttings and rooted liners.

Perennial Solutions: Scabiosa columbaria Giga Series