One of the important factors in successful plantings is the correct spacing of plants at the time of transplanting. Every plant requires space in which to develop normally. The result of close planting is eventually an overcrowded condition and a lack of healthy, well-developed foliage, flowers, and fruit. The more vigorous specimens crowd out the weaker ones and unless a "thinning-out" process is adopted, the mass effect becomes quite uneven and ragged.
The reason for most overcrowded plantings is the desire on the part of the designer to obtain an immediate effect. Too often our impatience and unwillingness to wait until plants mature and "fill out," develops many errors. Three years after transplanting is the normal period required for shrubs, two years for perennials, and eight to ten years for average nursery-grown trees to make the necessary growth to overcome the bare effect of the border or row of trees when planted in small sizes.
The question often arises as to whether or not it is better to use average-sized nursery stock (three to four-year-old stock) or to use large overgrown shrubs. Many people feel that an immediate effect is desirable and therefore the larger the shrubs that are used the more quickly the effect will be produced. The author has had considerable experience with both types of plantings. The nursery shrub will require anywhere from two to four years under normal spacing before it will develop sufficiently to produce the desired effect in the mass planting. On the other hand, the large, overgrown shrub which will produce an immediate effect generally requires severe pruning and cutting back in order to produce any growth which will fill the plant at the bottom and the top. This renovating process requires from two to three years. Therefore at the end of this period the general effect of the plantation is about the same whether large, overgrown shrubs are used or whether the smaller nursery specimens are used.
The correct method to adopt in general planting work is to allow sufficient space between plants for the normal development of each. Planting too close, although providing a more finished appearance during the first one or two seasons, is far more undesirable than liberal spacing. It is not practicable to lay down a well-defined rule for spacing plants. The planter can best be guided by the knowledge that he is seeking an immediate mass effect of foliage, requiring close spacing, or that he will wait during a proper period before expecting to see the plantation well developed. See list re "Spacing of Plants" which follows.