Since there is more or less cramping of roots, it will be necessary to make the soil richer than would be required were the plants to grow in the garden. The most desirable soil is one that does not pack hard like clay, nor contract much when dry, but remains porous and springy. Such a soil is found in the potting soil used by florists, and it may be obtained from them at from 50 cts. to $1 a barrel. Often the nature of the soil will be such as to make it desirable to have at hand a barrel of sharp sand for mixing with the soil, to make it more porous and prevent baking.
Some pot the plants and then set them in the window-box, filling the spaces between the pots with moist moss. Again, they are planted directly in the soil. The former method, as a general rule, is to be preferred in the winter Window-Garden; the latter during the summer.
The plants most valuable for the purpose are those of drooping habit, such as lobelias, tropæolums, _Othonna crassifolia_, Kenilworth ivy, and sweet alyssum. Such plants may occupy the front row, while back of them may be the erect-growing plants, like geraniums, heliotropes, begonias, etc.
Just what plants will be most suitable will depend on the exposure. For the shady side of the street, the more delicate kinds of plants may be used. For full exposure to the sun, it will be necessary to select the more vigorous-growing kinds. In the latter position, suitable plants for drooping would be: *tropæolums, *passifloras, the single petunias, sweet alyssum, lobelias, verbenas, mesembryanthemums. For erect-growing plants: geraniums, heliotropes, etc. If the position is a shaded one, the drooping plants might be of the following: tradescantia, Kenilworth ivy, *senecio or parlor ivy, sedums, *moneywort, vinca, *smilax, *lygodium or climbing fern. Erect-growing plants would be dracænas, palms, ferns, coleus, centaurea, spotted calla, and others.
For shady situations the main dependence is upon plants of graceful form or handsome foliage; while for the sunny window the selection may be of blooming plants. Of the plants above mentioned for these two positions, those marked with an asterisk (*) are of climbing habit, and may be trained up about the sides of the window. Others will be found among the climbing plants mentioned under _Vines_, _Annuals_ and _Basket Plants_.