Of two seasons' duration from seed to maturity and death.
|Standard Cyclopedia of Horticulture|
Biennials. Plants that bloom a year after the seeds are sown, then make seeds and die. Familiar examples among vegetables are cabbage, turnips, celery and onions, but in warm or long-season climates they become annuals. Even in northern gardens, celery, carrots and beets, if permitted to crowd, will often run to seed the first year. On the other hand, many biennials, such as hollyhocks and others, are practically perennial because they self-sow, or multiply by offshoots, so that there is little danger of losing them.- Such cases give rise to discussion as to whether a plant is an annual, biennial, or perennial, but the practical problems are few and simple, and are commonly connected with the following favorite flowers:
Hollyhock (Althaea rosea), snapdragon (Antirrhinum majus), English daisy (Bellis perennis), Canterbury bells (Campanula Medium), steeple bellflower (Campanula pyramidalis), sweet william (Dianthus barbatus), foxglove (Digitalis purpurea), horned poppy (Glaucium luteum), French honeysuckle (Hedysarum coronarium), morning campion (Lychnis dioica), evening campion (Lychnis alba), rose campion (Lychnis Coronaria), honesty (Lunaria annua; L. biennis), pansy (Viola tricolor x) tufted pansies (Viola cornuta x.)
Every beginner desires to know what to do with the seedlings that spring up in every border by the dozen or hundred around sweet williams, foxgloves, lark spurs, hollyhocks, and the like. All that is necessary is to thin the seedlings and transplant some at any convenient time before autumn to the positions in which they are to bloom next year. This practice, however, does not suit those who want only the finest varieties, for these do not come true from seed. Therefore, they must buy seeds every year of the best varieties of highly- bred groups, such as sweet william, foxglove, English daisy, Canterbury bells, and hollyhocks, or else buy plants. If a very fine variety appears, it is desirable to multiply it by methods other than seed-sowing if possible, e.g., by offsets, cuttings or division. Named larkspurs cannot be kept a long time, owing to disease, unless propagated by cuttings every year. Double hollyhocks can be maintained by division and by keeping the leaves coated constantly with ammoniacal copper carbonate, which is less unsightly than bordeaux. A German cultivator avers that one should save seeds from diseased hollyhock plants instead of healthy ones, and declares that he has raised 1,500 such seedlings that proved immune. So far as known, this has not been thoroughly tested in America.
Those who do not want such expense and care, and prefer lusty, many-flowered plants of ordinary varieties to sickly specimens of high-bred types, will find it cheaper and easier to collect seeds as they ripen and sow them immediately. Color discords can be mitigated by thinning out or transplanting offenders. This is the way to secure gorgeous masses of blue delphiniums, if one cares more for color than size and form.
What to do with famous English spring flowers that dislike our hot summers is another common problem. The beginner finds that violets, pansies, daisies, primroses, polyanthus, and auriculas, will not bloom all summer, as they do in the cool, moist climate of England, unless in similar climates (e.g., at the seashore or in the northern tier of states), and then only with special care in seed-picking, cutting-back, fertilizing, watering. At best the summer bloom is only intermittent, rarely massive, and the common practice is to treat these species frankly as spring bedding plants (April 15 to May 15 near New York), and when their glory is past discard them or move them to some moist, shady spot in which there is a better chance for casual summer bloom and a tolerable autumn show than in the hot sunny border.
Those who cannot afford greenhouses may easily have larger and better flowers of the species just named by the use of coldframes. They are particularly enjoyable while the snows of March are on the ground.
In these days of cheap greenhouses, everyone wants cut-flowers the year round, especially long-stemmed, long-lasting kinds in many colors. Consequently snapdragons and ten-weeks stocks have become popular.
The commonest way of raising biennials is to sow the seeds in an outdoor seed-bed in summer, and in autumn transplant the seedlings to their permanent quarters. English books have always disappointed Americans by advising that this be done in June. But in America the best time is early August. Not only does one save two months' care, but June-sown biennials and perennials in our climate make plants that are too large to winter easily in coldframes, and they often try to bloom just when the killing frost of autumn comes.
A much better way is to sow the seeds in flats in cold- frames (for protection against summer showers) and to winter the young plants in frames. This is the way to secure the finest white foxgloves, Canterbury bells, larkspurs, and steeple bellflowers.
Professional gardeners often prefer to treat biennials as half-hardy annuals, i.e., they sow the seeds in greenhouses in March and set the young plants outdoors in May. On new places this saves a year; it is especially worth doing with snapdragons and intermediate stocks.
Many of the flowers named above are technically perennial, but in practice they are so short-lived that it usually pays to raise a fresh batch from seed every year.
|This article contains a definition from the Glossary of Gardening Terms.|