Achillea

Vaughan, M. J. 1988. The Complete Book of Cut Flower Care. Timber Press, Portland,
Ore.
Many thanks to Elizabeth Dean for reviewing this section.
CALLISTEPHUS CHINENSIS 151
Callistephus chinensis China aster Asteraceae
annual China many colors 1–3'/2' (0.3–0.9 m/0.6 m)
China asters continue to be offered in various sizes and colors—including pastels,
bright blues, and electric reds—and breeders are still bringing plants to the
marketplace. Although popular in many circles, including Europe, the main
drawbacks of China asters are the relatively low yields and susceptibility to disease.
Production has moved mainly to the greenhouse, where more control of the
environment is possible. China aster, an annual, should not be confused with
perennial asters, which are included under Aster.
Propagation
Seed germinates in 3–7 days if placed under intermittent mist at 70–72F (21–
22C). Approximately 0.12 oz (3.5 g) of seed yields 1000 plants (Nau 1999). Seed
may also be direct sown in the field in early spring at the rate of 0.09 oz per 100'
(10 g per 100 m) for summer production (Kieft 1996). Some cultivars are also
propagated vegetatively, from cuttings.
Growing-on
Seedlings should be transplanted to cell packs or 3–4" (8–10 cm) pots at the first
true leaf stage, then grown at 70/60–62F (21/15–17C) day/night until roots are
well established. Do not allow plants to become root bound. Maintain plants
under long days of approximately 15 hours with incandescent lights when natural
short days occur. Fertilize with 100–150 ppm N with potassium or calcium
nitrate.
Environmental Factors
Photoperiod: Flowers develop most rapidly when a period of long days is followed
by short days (Cockshull 1985). The term given to this plant is a “longshort
day” plant. That is, plants are induced to flower under LD, and then
develop more rapidly under SD after induction. If plants are provided with continuous
LD, they flower more slowly but on longer stems than do those that are
exposed only to SD, a useful characteristic for cut flower production. Flowering
of laterals is also delayed when plants do not receive SD treatment (Goldsberry
et al. 1989). Even though research has shown that only 7 LD are needed for
flower initiation (Doorenbos 1959), approximately 4–5 weeks of LD are necessary
to adequately “prime” the plant for SD treatment. Flowering is not acceler-