Low-growing shrubs like Deutzia lemoinei are generally bought in 2- to 3-foot size, taller-growing ones like viburnums in 3- or 4- to 5-foot sizes, according to where they are to go.

Small trees, like dogwood, are bought in the 6- to 8-foot size if for masses, and in the 10- to 12-foot size, or larger, for specimens. These same sizes are generally used for conifer ous evergreens for screening or accent. Shade trees are little use unless they are at least 14 to 16 feet high, or 21/2 to 3 inches in diameter (caliper). The larger these are when planted, the quicker effective shade and shadow are produced.

Spacing is important in figuring quantities. If plantings are made too thick, they soon crowd and have to be thinned. If too thin, they take forever to become effective, and mean while require a great deal of maintenance because the open spaces become weed-infested. Remember that all plant groups are compositions, and that a happy medium between too thick and too thin is the ideal. Filler plants (less expensive, quick growing varieties, page 153), are often used to fill in the open spaces between more permanent plants. The intention is to get immediate effect. You must remove these fillers when the planting begins to crowd. The danger is, of course, that you will not do this in time (if at all), and finer plants will be ruined by overcrowding. Otherwise filler planting is sound practice.

Low-growing shrubs like indiancurrant, coralberry, and Japanese barberry are usually set 31/2to 4 feet apart; larger sorts, forsythia and spireas, are set 4 to 5 feet apart; and the very tall-growing shrubs, lilac, mockorange, and bush honey suckles, 5 to 8 feet apart. Small trees in masses can easily be set as far as 8 to 10 feet apart, but if they are so widely spaced, it is wise to underplant with a filler for immediate effect without depriving the permanent plants of space for future development.

Large-growing conifers-pines, hemlocks, and spruces- should be set 6 to 10 feet apart, if a solid grove is desired, but more widely spaced, 10 to 20 feet, when used as speci mens or accents. Shade trees should be spaced no closer than 20 feet, and 40 feet is preferable. Set evergreen hedge plants 31/2 feet apart, and deciduous ones, 2 feet.

Perennial and annual quantities can be estimated on a square foot basis. Allow 4 square feet for each husky plant of phlox or hardy aster, and 6 square feet for a large peony. Low foreground and edging material needs 1 to 2 square feel per plant.