Blue flowers are not common in the autumn garden. Yet there are a few species to choose from—among them, aconitum and asters—and they trail interesting histories.
Aconitum
Commonly called monkshood from the helmet or hood shape of the individual flowers, these plants often grow to five feet. They add height to the perennial border and are beautiful cut flowers. However, all parts of the plant are poisonous, especially the roots, and particularly if the plant comes in contact with open scratches or is ingested by children or pets. The ancient Greeks were aware of its toxicity and may have used the plant to make arrow poison; aconitum may refer to the Greek word for dart. The plant is also called wolf’s bane; it is thought that arrows, dipped in aconitum, were used to hunt wolves. On the other hand, one species (A.napellus) is the source of the heart medicine aconite.
About 100 species are native to temperate areas of Asia, Europe and North America; two are commonly grown, along with hybrids. A. napellus, common monkshood, comes from northern Europe and blossoms in late summer. Plants may grow to four feet with indigo flowers. A.henryi, from western China, blooms slightly later, may be a foot taller, and has more purplish blooms.
Aconitum is tolerant of shade, although it prefers sun if the soil is not too heavy. It can be left undisturbed for many years and will form attractive, upright clumps; staking is sometimes helpful. It favors cool climates.
Autumn or spring planting is best, when roots can be split to increase stock. Seed is slow to germinate; germination may be more successful if the seed is sown when ripe rather than waiting for early summer.
Aster
Asters may figure prominently in fall perennial gardens; some species make wonderful cut flowers.
The name is derived from the Greek word for star. This flower is also called the Michaelmas daisy: introduced to England in 1720, it flourished and was in full bloom on St. Michael’s Day, September 29, by the time England adopted the Gregorian calendar in 1751.
There are 250-600 species of aster, native to temperate areas of the world. Asters are hardy, easy to grow, and multiply rapidly; they may need frequent division. They come in various heights, from six inches to eight feet, and in a range of colors; many varieties are available in shades of blue.
Asters can be planted in autumn or spring in a sunny location—they tolerate a little shade—and are not particular about soil. They can be readily increased by division, seed, or stem cuttings.
Sources
Geneve, Robert. 2000. A Book of Blue Flowers. Timber Press, Portland, Oregon.
Hunt, Peter, Ed. 1970. The Marshall Cavendish Illustrated Encyclopedia of Gardening. Marshall Cavendish , New York.
Connie Ganong - Connie Ganong’s interests in literature and horticulture led to study in biology (B.A.), English (M.A.), and agricultural journalism ...
