December 2008 Culture

Geum coccineum ‘Cooky’ By Paul Pilon

Many growers are looking for a perennial that is easy to produce and provides a bright, cheerful display of color to supplement their early- to mid-season product lines. Geum 'Cooky' is a great perennial for early sales and is largely underutilized by commercial growers. 'Cooky' produces pleasing bright-orange toned flowers atop short 12-inch stems above attractive evergreen mounds of hairy, coarse-pinnately lobed leaves. With its compact growing habit, first-year flowering and ease of production, 'Cooky' is well suited for commercial growers.

Geum coccineum belongs to the Rosaceae family, which includes only a few commercially produced perennials, including alchemilla, aruncus, filipendula, potentilla and prunus. 'Cooky' is commonly used as a bed and border perennial near wooded areas and also can be planted in containers or used as cut flowers. In the landscape, they are resistant to rabbit feeding and attract butterflies to the gardens. They perform well across much of USDA Hardiness Zones 4 to 9 and AHS Heat Zones 9 to 3, where they prefer to be grown under partial shade, although they can tolerate some full sun.

Propagation

Geum 'Cooky' is available from Benary Seeds as Apex seed, which is treated to provide growers with improved germination, increased uniformity and more transplantable plugs.

'Cooky' is commonly sown in 288- or 220-cell plug trays. Light is required for germination; do not cover the seed with germination mix or vermiculite after sowing. Moisten the seed flats and move them into a warm environment, where the temperatures can be maintained at 64-68¼ F for germination. Keep the media slightly moist but not wet during germination. It is best to germinate them in a chamber where uniform moisture levels and temperatures can be maintained. Using a germination chamber will also increase both the germination rate and percent germination.

The seeds should be germinated in 10 to 15 days after sowing. Several growers apply a very light covering after the radicals have emerged. Once germinated, they can be grown at temperatures of 62-66¡ F. Following germination, reduce the moisture levels somewhat, allowing the growing medium to dry out slightly before watering to help promote rooting. Fertilizers can be applied once the true leaves are present, applying 100-ppm nitrogen every third irrigation or 50 ppm with every irrigation, using a balanced water-soluble source. When the plugs are grown at 64¡ F, they are usually ready for transplanting in seven to nine weeks.

Production

Geum 'Cooky' is often produced in 1-gallon or smaller-sized containers. Growers commonly use a single plug transplanted into small container sizes, or when fall planting, large container sizes. When spring planting vernalized plugs, it is recommended that growers transplant two plugs per gallon container to fill it out. When transplanting, the growing medium should be even with the top of the plug. They perform best when grown in a moist, well-drained medium with a slightly acidic pH: 5.8-6.4. Geum requires an average amount of irrigation and does not tolerate overly wet or dry conditions. Keep them moist but not consistently wet.

Geums are light to moderate feeders. Growers commonly deliver nutrients using either a constant liquid fertilization program, feeding at rates of 75- to 100-ppm nitrates, or a controlled release fertilizer incorporated at a rate equivalent to 3/4 to 1 pound of nitrogen per yard of growing medium.

Given their compact growth habit, it is usually not necessary to control the plant height. However, during periods of low light levels, when grown at high plant densities, or when grown with luxury nutrient levels, excessive plant growth (plant width) might occur requiring some type of height-management strategy. The growth of 'Cooky' can often be reduced by providing adequate spacing between the plants. It may be necessary, although not common, to use chemical plant growth regulators to control their growth. In the northern parts of the country, applying spray applications of paclobutrazol (Bonzi, Paczol or Piccolo) at 30 ppm or uniconazole (Concise or Sumagic) at 5 ppm is recommended. One to two applications seven days apart should give adequate height control.

Insects and Diseases

Aphids, leafminers and spider mites are commonly observed feeding on geum. Of these insects, aphids are the most problematic. Preventive control measures are not needed; the presence of these pests can be detected through routine scouting, and if necessary, control measures can be implemented.

There are a number of disease organisms known to infect geum, including Botrytis, downy mildew, powdery mildew, root rots and rust diseases. Similar to controlling insects, plant pathogens are often not problematic for growers; early signs of these diseases can be detected with routine crop monitoring. To prevent the occurrence of these diseases, it is best to manage the environment by providing proper plant spacing and adequate air movement, controlling humidity, monitoring the salt levels of the growing mix, and providing proper irrigation practices.

Forcing

Geum 'Cooky' is easy to force into bloom, and is most commonly produced for early spring sales. They will flower the first year from seed, but produce more flowers when they have been overwintered or vernalized. 'Cooky' does not have a cold requirement, but cold is beneficial and will reduce the time to flower slightly, improve the uniformity of bloom and increase the number of flowers produced. Geum 'Cooky' is classified as a day neutral plant and will flower under any photoperiod.

Following vernalization, they bloom very quickly and can be easily grown for early season sales. To obtain full, flowering plants for spring sales, it is beneficial to plant them during the late summer of the previous season. Transplant plugs into the desired container during late August to early September, bulk them up before winter, overwinter them and force them to bloom in the early spring.

The time to bloom after vernalization is a function temperature. 'Cooky' grown at 65¡ F will take approximately seven weeks to reach flowering, while plants grown at 58¡ F will flower in nine weeks. Growers should note it will require an additional two to three weeks of production time to produce flowering plants when non-vernalized starting materials are used. Producing them at cooler temperatures increases the time to flower, but will improve the overall quality characteristics of the plant, such as the color intensity of the foliage and flowers.

Availability

Geum coccineum 'Cooky' is available to the industry as seeds, plugs or finished containers. The seed is supplied by Benary Seeds (www.benary.com) and available through many seed distributors. Plugs can be acquired from Swift Greenhouses, Inc. (www.swift greenhouses.com) or from several reputable plant brokers.