Before planting, survey the site fo

Before planting, survey the site for potential hazards to plant growth. For instance, new construction sites are often littered with pieces of mortar, plaster or limestone, creating an alkaline soil condition and inhibiting a plant's ability to absorb nutrients. Chemical spills, such as motor oil or gasoline, can also impair plant growth. It may be necessary to remove the top 6 to 8 inches of soil and replace it with a good grade of topsoil. Compacted soils also inhibit root growth.

Figure 1. Ornamentals can be grown on poorly-drained soils if they are planted on raised beds.Figure 1. Ornamentals can be grown on poorly-drained soils if they are planted on raised beds.
Poorly drained soils cause plant problems. Waterlogged soil will suffocate the root system and kill a plant. Improve poorly drained sites by deep tilling to break apart a layer of hard packed soil, or "hard-pan," several inches below the soil surface. Slope beds planted near a foundation away from the building, and route water from drain spouts away from plant beds. On extremely heavy soils, construct a raised bed, 12 to 18 inches high, of well-drained topsoil, and slope the sides of the bed away from the plants to avoid pockets of standing water. Another option is to install a sub-surface drainage pipe to carry water to another area (assuming there is somewhere for the water to drain