WINDOW BOXES AND HANGING BASKETS : Page 755
Not all of our plants can be used in window-box planting. Plantsfor this purpose must retain their foliage throughout the summer, theperiod of bloom must continue for a number of weeks, and the normalgrowth of the plant should not be impaired by crowding the rootdevelopment within a small area.
Two cardinal principles apply to the design and use of windowboxes. Never put window boxes on a building unless the architecturalcomposition requires them, and do not select for them plants whichare out of scale with the architectural detail. When planning thewindow boxes the effect of the colour scheme should be consideredfrom the inside of the various rooms in the house as well as the effectupon the aspect of the house itself.