A sloped lawn can be hard to plant, since rain and gravity work in tandem to wash away the soil and rooting plants. This is where sod can really help. Since it is applied in strips, it is less likely to wash out in the brief time it takes it to root. The following tips can further help you with sodding your slope.
Tip #1: Begin with good soil
It's standard practice to lay down a thin layer of new topsoil or compost before installing sod. This gives the sod a base that provides nutrients along with moisture retention. On a slope, a thin layer may not be sufficient. This is especially true if there is heavy clay soil beneath the topsoil, since any water will sit on top of the clay and quickly wash out the good soil. Instead, dig out the soil to the average depth of the roots of the grass variety you are planting – 6 inches is probably sufficient. Replace this with a good topsoil or topsoil and compost blend. Finally, till it in with the native soil beneath, so the good soil isn't just floating on top of the native soil.
Tip #2: Grade the slope
An uneven or bumpy slope can also pose an issue. In order to root, the sod must have full contact with soil beneath. If the slope isn't smoothed, parts of the sod may not root properly. Rake the slope after amending the soil so it is smooth and even. The grade of the slope should be gradual, with few if any bumps or irregularities.
Tip #3: Lay across the slope
When installing the sod, lay it horizontally across the sod instead of vertically down the slope. This way each sod strip is relatively level. This minimizes the chances of water getting under a sod strip and sending it slipping down to the base of the hill. When laid across the slope, while some water may get under the strip, much of it will flow over the top.
Tip #4: Stagger the joints
Make sure the joints between strips in adjacent rows don't line up. Instead, stagger the joints so no two joints are right next to each other. You don't want the joints to form canals that will allow water to course down the slope, since this will lead to erosion grooves.
Tip #5: Use sod staples
Sod staples are U-shaped stakes. Insert these into the sod at the corners of the sod strips, as well as anywhere that may need a little extra help in staying firmly against the slope. This will prevent the sod from being washed away before it can root. Once rooted, the staples can be removed.
Talk to a sodding professional such as Metro Sod & Seeding Inc for more help in getting your slope planted.