Probably no flowering plant grown and loved today has a richer history than the chrysanthemum. Oriental in origin, it has been a symbol of Chinese culture for more than two thousand years. Introduced to Europe in the late 1600's, it found its way to the United States about 1800, and interest in its development and cultivation increased until today it is surpassed only by the geranium as the favorite pot plant.
Chrysanthemums grown under glass normally flower during October, November, and December. However, manipulation of light and temperature can cause normally short-day chrysanthemums to flower at any season you desire. Long nights of winter set and develop buds in nature, so by covering the plants with dark cloth from 5 p.m. to 8 a.m. you can initiate early budding. Conversely, if days are lengthened with artificial light, flowering can be delayed. Growth patterns may be further altered by pinching on a special time schedule that relates to bud formation, and by disbudding. If you plan to specialize in chrysanthemums, cultural directions covering these and other interesting and important procedures should be studied carefully.
Chrysanthemums like a loose, fibrous soil rich in organic matter at least one-fourth coarse peatmoss or well-rotted manure. Roots must have an adequate supply of oxygen and soil must be well drained, especially if plants are grown in pots. Soil used in the mixture must be sterilized to prevent the fungus of verticillium wilt from attacking the plants.
Bud development for normal fall flowering takes place from about the 15th to 25th of August. During bud formation, night temperature should be lowered gradually, down to 56 F if possible; a lower temperature than this, however, causes bud development to cease or no buds to develop at all.
Chrysanthemums grow to considerable height, so stems must be supported. If you specialize in and devote your entire greenhouse to chrysanthemums, a bench wiring frame installation is necessary. Frames should be set up when plants are quite short so support will be available to assure straightness as stems elongate. Otherwise, individual stakes of wire or bamboo are satisfactory; fasten stems to the support at regular intervals with string or plant ties.
Buy rooted cuttings from your local garden center or order from a mail-order firm that specializes in chrysanthemums. Space cuttings sufficiently far apart in bench to allow free movement of air. Mulch with peatmoss during summer to keep soil moist, especially if cuttings are benched early in May (necessary with some varieties). Take care to set cuttings into the bench only to the depth they previously grew in the rooting medium. Daily misting encourages growth and prevents wilting of newly benched cuttings. Fertilizer is not necessary until buds begin to form; then a liquid fertilizer application every two weeks is beneficial until color appears in buds.
After your first season of growing chrysanthemums, you might like to make your own cuttings. Place a few stock plants in a cool section of the greenhouse. Water sparingly and do not crowd. As the warmer, brighter days of early spring approach, growth will resume. Take cuttings from this new growth from April through June, depending on the varieties. Cut or break 3 to 5 inches of tip growth, insert in sand, peat and sand, or perlite. A root-promoting powder may be used if desired, but most chrysanthemums produce roots within three weeks whether so treated or not. Transplant as soon as roots have developed, and shift as required to prevent plants from becoming potbound.
There are so many varieties of chrysanthemums, and such variations of colors and kinds, it would be difficult to suggest a list. Growers catalogues furnish complete descriptions and color groupings from which you can make your own selections. Chrysanthemum frutescens (marguerite; Boston-yellow-daisy), and Chrysanthemum Parthenium (feverfew) are grown according to the same cultural suggestions given above for chrysanthemums.