Those who garden in northern regions grow accustomed to scanning seed catalogs, greenhouses and nurseries for plants that thrive in our cool climate and short growing season.

One group of plants that flourishes under our growing conditions includes the daisies.

While “daisy” is the name of the roadside flower, the term “daisy” also is used generically to describe members of the “compositae,” or composite, family. Garden asters are members of this group. Botanically speaking, they are cousins to the roadside daisy and the black-eyed Susan. Like their relatives, asters add more to the garden than a splash of color. Many asters make excellent cut flowers. Dwarf varieties may not be suited to cutting, but they are perfect plants to tuck into corners of the garden.

Some asters are perennial, others annual. The China aster, an annual, is one of the more common. Varieties of this plant offer red, blue, white, creamy yellow, lavender and pink flowers. They grow anywhere from 10 inches to 3 feet in height. Low-growing varieties are self-supporting, but tall varieties become heavy during flowering and may need staking. Pinching the terminal or top bud of the plant will encourage side growth and may offer the plant some stability.

An additional benefit of pinching is that it will cause the aster to put energy into more, smaller, short-stemmed flowers, rather than fewer long-stemmed flowers. Thus, if you want to use your asters for cutting, consider staking them, rather than pinching them. If you want a profusion of color in the border garden, encourage a lot of flowers by pinching.

Once they begin to flower, China asters bloom for about four weeks. When selecting seeds or seedlings, be sure to choose varieties that will yield blooms early, mid- and late season. Plant China asters in full sun or light shade and in neutral soil. Snip the blooms once they are spent to encourage another round of flowering.

China asters do have a few culture problems. When weather is hot and dry, spider mites and aphids may be present. These insects feed on the juice of the plant, literally sucking the life from it.

Frequently a problem for the plant is a minute organism that causes a condition known as aster yellows. This organism is passed to the plant by way of the gastric juices of leafhoppers. In addition to yellows, asters sometimes are subject to stem rot, a disease that causes dark lesions of injured tissue. It causes the plant to rot at the surface, obstructing the flow of nutrients to other tissues of the plant.

To minimize problems that plague these lovely plants, be aware of a few general steps that prevent or control diseases for most plants. Select varieties that are resistant to disease. Plant members of the same species in different areas of the garden from year to year. This will make it harder for diseases to “find” host plants in the garden, and will break the cycle of the disease by not allowing it to find a host in a particular year.

Always discard plants that have become infected with disease when they are beyond regaining liveliness. Burn the plant to destroy the organism. Never discard the diseased plant tissue in the compost pile. This practice can spread soil-borne disease when the composted material is added to garden soil in subsequent years.

Check seed catalogs and local greenhouses for varieties that will work well for your needs and wants. Color Carpet, Dwarf Queen, Pixie Princess and Pinocchio are dwarf varieties that make great bedding plants. Powder Puff, Sea Stars, Giant Princess and Duchess are perfect for cutting.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, c/o MaineWeekend, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. Selected questions will be answered in future columns. Include name, address and telephone number.