Before you add trees and shrubs to your landscape, you first need to evaluate your yard’s current state. Two areas that particularly affect trees and shrubs are slope and wind. (Click here for a detailed list of other conditions to assess)

Slope

The most important aspect of slope in your landscape, as far as trees and shrubs are concerned, is its influence on how water moves across the soil’s surface. On steep slopes, fast-moving water can wash the soil away from their roots. In flat landscapes, water sometimes puddles around them. People who work with soil often describe the steepness of a hill as percent slope. The following steps show you how to measure the percent of a slope. (See the image below as well.)

1. Assemble your tools — a carpenter’s level, tape measure, a 10-foot straightedge, and a buddy.
2. Position the straightedge and level.
   Set one end of the straightedge at the top of the slope and support the other end over the downhill slope. Place the carpenter’s level in the middle of the straightedge. Adjust the downhill side of the straightedge up and down until the carpenter’s level shows that the straightedge is level. The distance that the straightedge measures is called the length, or horizontal run.
3. Measure the height of the straightedge.
   Have your buddy measure the distance from the downhill end of the straightedge to the ground. The height of the slope at that point is called its vertical rise.
4. Calculate the percent slope.
   Use the following formula to calculate the percentage of your slope:
   (vertical rise ∏ horizontal run) ¥ 100 = percent slope
   For example, if the rise or distance from the ground to the end of the straightedge is 2 feet and the run or length of the straightedge is 20 feet, your percent slope is 10 percent.

Water moves very slowly and may puddle on grassy, 2 percent slopes. On steeper slopes, however, water moves more quickly and can wash away the soil. Plant roots hold the soil in place while their foliage decreases the impact of heavy rain on the soil surface. On slopes that measure greater than 20 percent, use shrubs or other low maintenance, ground-covering plants that don’t require mowing.

Wind

If your site lacks protection from hills or trees or if you live near tall urban buildings, strong winds may blow through your yard. Wind contributes to soil erosion and plays a role in how well plants survive the winter in freezing climates. Gentle breezes cool hot summer days and help prevent some plant diseases, but gusty and stormy winds blow away your patio chairs and break tree limbs.

If you want more protection from the wind, you can plant a windbreak. Windbreaks planted perpendicular to the prevailing wind offer the most protection, but they must be at the right height and distance from the place you want to protect. For the most wind protection, use the following guidelines:

• Determine the direction of the prevailing winds.  ....read more