Annuals, Biennials and Perennials for Your Garden Beds and Borders
Perennials are plants which die to ground level every winter, and shoot again in the spring. Each year they grow wider and produce a greater and greater quantity of bloom. Their main uses are in herbaceous and mixed borders.
There are two main methods of propagating perennials, division and seed. Seed, not feasible for hybrids and varieties which will not come true to type, should be gathered as soon as ripe, and sown out of doors in spring or autumn under cloches or in frames. In some cases the seeds need the gentle warmth of a greenhouse or airing cupboard. Most seeds need shade to germinate, and should be covered with brown paper just until they appear above ground. Division is achieved by lifting the plants, inserting two forks back to back and gently teasing the plants apart. Occasionally perennials can be increased by, but this is the exception.
Biennials are plants that take two years to complete their cycle of growth. During their first year they usually build up a rosette of leaves and a strong root system; they rest over the winter then flower, set seed and die. Like, their main garden use is for bedding, or for filling gaps in the border. The normal form with is to sow them the year before they are wanted in flower, but this presents the problem of where to grow them until they are put in their flowering positions: in it is usually better to buy biennials the year they are needed. In larger gardens keep a place for propagating plants; sow seed out of doors, in shallow drills; cover large seed to three or four times its own thickness, small seed only shallowly. First work the to a fine tilth and enrich with superphsophate (2 ounces per square yard) and some fine peat to prevent drying out in hot weather. After germination the should either be thinned out to six to nine inches apart or transplanted to nursery beds and planted six to nine inches apart in rows fifteen inches apart. Keep well weeded and watered until autumn, and then transplant to their flowering positions.
Annuals are plants which complete their life cycle in just one season. Though short-lived, most annuals produce an unrivalled wealth of bloom. Their main use is in bedding schemes, for filling gaps in the shrub or herbaceous border, or for window boxes, tubs and other containers. Most come from sunny parts of the world, and need to be grown in open positions in full sun. For best results plant them in soil that has been well-prepared beforehand and enriched with, well-rotted manure or superphosphate (2 ounces per square yard).
Annuals are sub-divided into those that are hardy () and those that are tender ( ). Their garden uses are the same, and, while they are both raised from seed, seed needs to be sown at different times under different conditions.
Hardy annuals may be sown either in spring or in autumn, preferably where they are to flower. The seed should be sown broadcast or in shallow drills, and only lightly covered. Seedlings will need thinning twice, the first time when they are about an inch high, the second when they reach half their ultimate height: the ideal distance between annuals is half their ultimate height. It is always safer to sow in spring, but autumn sowing is a gamble which means a longer flowering season if it comes off. Plants should be about three inches high before the frost sets in. August and September are the best months to sow.
Half-hardy annuals are sensitive to frost, and must therefore be sown out of doors after the frosts are over, which usually means May or June, or else must be raised in a greenhouse or frame in boxes, the seed being sown in February or March, hardened off and planted out in May or June. Raising in a greenhouse ensures a longer flowering season.