The border should be planted so thick as to allow the plants to run together, thereby giving one continuous effect. Most shrubs should be set 3 feet apart. Things as large as lilacs may go 4 feet and sometimes even more. Common herbaceous perennials, as bleeding heart, delphiniums, hollyhocks, and the like, should go from 12 to 18 inches. On the front edge of the border is a very excellent place for annual and tender flowering plants. Here, for example, one may make a fringe of asters, geraniums, coleus, or anything else he may choose. (Chap. II.)
Into the heavy borders about the boundaries of the place the autumn leaves will drift and afford an excellent mulch. If these borders are planted with shrubs, the leaves may be left there to decay, and not be raked off in the spring.
The general outline of the border facing the lawn should be more or less wavy or irregular, particularly if it is on the boundary of the place. Alongside a walk or drive the margins may follow the general directions of the walk or drive.
In making borders of perennial flowers the most satisfactory results are secured if a large clump of each kind or variety is grown. The herbaceous border is one of the most flexible parts of grounds, since it has no regular or formal design. Allow ample space for each perennial root,—often as much as three or four square feet,—and then if the space is not filled the first year or two, scatter over the area seeds of poppies, sweet peas, asters, gilias, alyssum, or other annuals. Figures 237-239, from Long (“Popular Gardening,” i., 17, 18), suggest methods of making such borders. They are on a scale of ten feet to the inch. The entire surface is tilled, and the irregular diagrams designate the sizes of the clumps. The diagrams containing no names are to be filled with bulbs, annuals, and tender plants, if desired.
It must not be supposed, however, that one cannot have a border unless he has wide marginal spaces about his grounds. It is surprising how many things one can grow in an old fence. Perennials that grow in fence-rows in fields ought also to grow in similar boundaries on the home grounds. Some of garden annuals will thrive alongside a fence, particularly if the fence does not shut off too much light; and many vines (both perennial and annual) will cover it effectively. Among annuals, the large-seeded, quick-germinating, rapid-growing kinds will do best. Sunflower, sweet pea, morning glory, Japanese hop, zinnia, marigold, amaranths, four o’clock, are some of the kinds that will hold their own. If the effort is made to grow plants in such places, it is important to give them all the advantage possible early in the season, so that they will get well ahead of the grass and weeds. Spade up the ground all you can. Add a little quick-acting fertilizer. It is best to start the plants in pots or small boxes, so that they will be in advance of the weeds when they are set out.