No garden is complete without its quota of annuals. The so-called perennial garden, to be really successful, must be supplemented each year with a quantity of annuals, especially if the garden is to be studied in close detail. If only the larger mass effects of flowers and foliage are required, a perennial planting properly selected is sufficient in itself.
The opinion prevails among those who have devoted but little study to this subject that a complete flower garden can be developed during the first one or two years after planting through the use of properly selected types of perennials only. Such a garden may be developed after the first one or two years, under the care of an expert gardener. It is almost impossible to develop such a garden in the early stages, because perennials, on account of the nature of the plants, continue each year to increase their mass and so require more space for their normal development. Therefore, when perennials are first planted, sufficient space should be allowed between plants to permit of a normal development for at least three or four years, at the end of which period the clumps of plants, except the peony, should be "divided." (See "Maintenance of Perennials.") If the first planting is not overcrowded there will be during the first year, and often during the second year, bare spots in the garden which should be filled with annuals. Perennials during the first year after transplanting rarely become established sufficiently to produce normal flower effects, and this is one reason for the use of annuals to develop a successful garden.
Annuals are plants which are grown from seed each year and whose roots die each winter. The roots of perennials continue to live in a dormant condition and develop new growth again at the top with the coming of the next spring.
The first principle in the successful development of any flower garden is to determine the use for which the flower garden is developed. A garden designed, either of annuals or of perennials, to show a succession of interesting bloom and to make an interesting garden picture, either as masses of colour or spots of colour, is a different garden from the so-called cut-flower garden, from which the flowers, as soon as they mature, are apt to be cut and used for table decoration. The best success in garden development is obtained when a clear-cut line is drawn between the so-called cut-flower garden and the flower garden as a piece of landscape design. There is nothing more discouraging to the expert designer than to see masses of flowers at the height of their bloom, and at a time when they should be most effective in the garden design, deliberately cut for table use and a resulting criticism extended that the garden is not a success because it has no flowers. This discussion applies equally well to a garden filled with perennials and to a garden filled with annuals. A garden should be, if space permits, either for one purpose or for the other, and if a space is desired where cut flowers may be obtained, then a separate garden should be provided from which flowers may be cut as soon as they have matured.
There are many interesting questions concerning the use of annuals. Perhaps the most interesting group of annuals is that containing the plants which are valuable for cut flowers, such as the larkspur, marigold, snapdragon, Mexican poppy, and nasturtium. These plants to be most successful for cut flowers should be in rows for purposes of cultivation, and given ample space to develop fully. Most of them, as with the other annuals which have early flowers, are sown in the seed beds in mid-February and early March or in the hot frames during the last of March and early April and later transplanted. Most of the annuals can be sown in the open ground during the last of April and early May, but the flowering season is apt to be much shorter because the flowers mature at a later date.
There is a group of annuals which are extremely desirable as ground cover and edgings. They are plants which, when sown thin in the open ground, need not necessarily be thinned out although an intelligent thinning is better. These annuals form beautiful edgings to the flower borders and fill many otherwise bare spaces in the front of the lower annual plantings.
There is a group of annuals which should preferably be sown in the open ground where they are to bloom, and which should be thinned out to the proper spacing between plants as the small plants develop. These annuals are difficult to transplant successfully, and include such types as baby's breath, lupine, nasturtium, cornflower, and poppy,Annuals, unlike perennials, can be started in many instances at different periods during the season, in order to insure a succession of bloom. There is a normal period required between the time of seeding and the time of blooming, and if this period is definitely known, then at intervals of not less than ten days or two weeks three or four successive sowings may be made in the early and late spring so that a continuous succession of bloom from these plants may be obtained during the summer months. Typical of these plants are the phlox, forget-me-not, and baby's breath.
Plate XXXVII. Not only because of the interesting colour of its fruit in combination with the fruit of other shrubs, but because of the size and abundance of its fruit, the snowberry is one of our conspicuous and valuable shrubs. (See page 162, group XX-B)
Most of our annuals can be sown, if necessary, in the open ground. There are a few types, however, which must be started in seed beds, either in a greenhouse or in hot frames, in order to produce good bloom before the frost injures the tops. These types include the China asters, cosmos, ten-weeks' stock, petunia, and butterfly flower, all of which require a longer season for the period of maturing after seeding. Many times when the seeds of these plants are sown late, the plants reach their mature development and are on the point of producing flowers when they are suddenly injured by an early frost.
It often becomes necessary or desirable to supplement plantings of perennial or woody vines, which are naturally slow growing, with annual quick-growing vines to cover fences and lattice work. It is seldom that perennial vines can be planted and produce an adequate covering for a lattice work or fence during the first year. The time required for the full development of such woody vines as the clematis, bitter-sweet, and rose is from two to three years. In such instances the cup and saucer vine, hop vine, cardinal vine, and the morning glory can be planted to fill the bare areas during the first year or two. Many of these annual vines have a heavy foliage, valuable for screen effects, and the writer has therefore divided this group into two sub-groups, indicating those with delicate foliage and those with heavy foliage.