Hardy Biennials

Description. Hardy Biennials complete their cycle of life within two years, i.e. are sown one year, flower the next year, produce seed, and then die. A few biennials can be induced to behave as annuals if sown very early in a warm greenhouse. Monocarpic plants die in the same way as biennials and annuals after having flowered and produced seed, but complete their cycle in an indefinite number of years. The most important true hardy biennials are Canterbury bells, foxgloves, and some verbascums, but wallflowers, forget-me-nots, double daisies, hollyhocks, and sweet williams are often treated as such. (There are also half-hardy and tender kinds for the greenhouse, such as Campanula pyramidalis and Humea elegans).

Soil and Situation. Most Hardy Biennials are adaptable plants, thriving in ordinary soils and sunny or partially shady positions. Soil should be prepared by thorough digging. A general garden fertilizer can be used in the spring as a top dressing. Animal manure is not desirable.biennial sweet william

Sowing and Planting. Seed must be sown every year to maintain a supply of flowering plants. The best time for sowing is May. Brompton stocks and forget-me-nots may be left until the end of June or early July. Seed may be sown outdoors in a sheltered border of finely broken soil, but the choicer kinds, such as Canterbury bell and Brompton stock, are best reared in an unheated frame in a semitshady position. Transplant seedlings 3 to 4 in. apart in rows 8 in. apart into a bed of similar character as soon as they can be handled conveniently, usually between mid-July and mid-August. Plants can be transferred to flowering quarters in September—October or March. Details of planting are exactly the same as for herbaceous perennials.

Propagation. By seed as above.

Cultural Routine. Practically non-existent except tor hoeing and removal of weeds. If desired, some plants may be retained after flowering to ripen seeds. These are handled in the same way as annuals retained for seed. Other plants should be removed and burnt or placed on the compost heap as soon as they have finished flowering.

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