The appearance of a perennial garden depends as much upon the shapes of your plants and how they are arranged, as upon their colors. Height You ll want to place the tallest plants in the back of the border, or in the center of an island bed, then work down in height, ending with the shortest plants around the edges of an island bed or the front of a border. Books and labels usually list the average mature height for a plant in bloom. Remember that many plants hold their flowers well above the foliage. This means that when the plant is out of bloom, it may be much shorter than the specified height.
Heights are also an average.
When grown in poor, dry soil, a plant may be only half as tall as the same plant grown in rich, moist soil. Width A plant s width, or spread, is just as important as its height. Width figures given in books or on labels are also an average. The actual width of a plant will vary depending on soils, geographical location and the age of the plant. Be careful about locating slow-growers very close to rapid spreaders.