Is your lawn tired? Has it lost its bounce under your feet? If so, now is a good time to examine and decide if you should revitalize your lawn this fall.
The best time of year for lawn renovation in western Washington is between September and mid-October because growing conditions are favorable and weed competition is much less/lower than in the spring.
Renovation can be as simple as overseeing a thin lawn area to repair damage or to increase tolerance to drought or shade. However, most home lawns age over time and suffer from two main ailments: thatch buildup and compaction. If your lawn shows signs of these conditions, it may be time for more extensive actions.
Your lawn needs renovation if thatch is greater than 1/2 inch and/or the underlying soil is compacted (water does not readily soak into the soil). If these conditions exist, you should dethatch and/or aerate your lawn area.
Renovation to restore beauty to an old lawn usually involves power raking, core aeration and overseeding.
Steps for a basic lawn renovation
1. Adjust your mower to approximately 3⁄4 inch (slightly lower for bentgrasses) and mow the lawn thoroughly.
2. Power-rake the lawn as many times as necessary to remove accumulated thatch. It is best to dethatch in opposite directions. Thoroughness is important.
3. Rake and remove loose material to expose the existing soil. The rake tines should be set to nick the soil surface to a depth of 1/8 to 1/2 inch. Add the thatched material to the compost pile.
4. Use a hand-held or a mechanical aerator to remove plugs from the areas of compacted soil. Go over the area three to five times in different directions. Break up the soil cores with a rake or add them to your compost pile.
4. Mow the lawn again at approximately 3⁄4 inch high.
5. Remove grass/add soil to high and low spots to obtain a uniformly smooth surface.
6. Overseed the lawn area uniformly at a rate of one-half of what is recommended on the bag. Use grass seed varieties suitable for our area (note: Turf-type perennial ryegrasses, fine-leaved fescues, and bent grasses are well-adapted to western Washington. Kentucky bluegrasses are usually short-lived in western Washington and only selected improved cultivars should be used and never seeded alone.).
A hand-held spreader can be used for small areas; a drop spreader is better for larger areas. Apply half the seed in one direction, and the other half in a 90-degree criss-cross pattern. Growth will initiate quickly both from the remaining grass stems and crowns and from the new seed.
7. Maintain constant surface moisture until the seed has germinated and the seedling plants have become well established.
8. Avoid traffic on the newly renovated lawn should for the first several weeks after seedlings emerge.
9. Mow when about 60 percent of the grass is 3-4 inches tall to a height of 2 ½ inches with a sharp mower. This will help keep weeds in check by blocking the sunlight from the soil surface. It also helps retain moisture and improves the overall health of the grass.
This restorative renovation will not be sufficient to re-establish a lawn if there are severe problems such as excessively compact soil, greater than 50 percent weed coverage or bare soil.
A total renovation (note: renovation would be an ideal time to take a sample to the Clallam County Conservation District for a soil test) would be needed and would involve killing the undesirable plants with one or more applications of a nonselective herbicide followed by tilling, power raking, adding compost and topsoil, leveling the ground then adding sod or overseeing, etc.
Bill Wrobel is a Clallam County Master Gardener.