Beat the weeds by turning some of your lawn into flowerbed
By Bonnie Orr
WSU Chelan/Douglas County Master Gardener
Many gardeners in North Central Washington have been talking about turf problems and how their lawns are weedier than ever before. The weed culprits seem to be spotted spurge, crab grass, Oxalis and Purslane.
These weeds established a foothold two summers ago when we had a week of intense heat that damaged the turf. The dead places in the lawn provided light to the dormant weed seeds.
In the succeeding two summers, these weeds have been having a field day and have overtaken many lawns. Correct timing for pre-emergent herbicides will help curb some of the weeds but be aware that there is a seed bank of thousands of seeds waiting for another opportunity to germinate.
It even might be time to reassess the amount of land you devote to turf. It is much easier to control weeds around shrubs and perennials when mulch is correctly applied. So, why not convert some of the lawn into new flowerbeds or areas of xeric shrubs? This is the time of year to undertake garden conversions.
The first step is to plan the perimeter by marking it off with a line of spray paint, so you create the area you have in mind. Take advantage of the cool weather because the lawn has essentially quit growing for the season, and the soil is dryer.
The easiest way to convert lawn to beds is to smother the turf plants. There are several easy ways to do this after you have determined the areas you want to change. These include:
After the final mowing, consider piling all the leaves and the grass clippings on the designated spot to the depth of 6 inches to 8 inches. If you mix the leaves and the grass clippings together, there is less likelihood the leaves will blow away. The advantage of using this system is that the worms and microorganisms will utilize the organic material over the winter and enrich the soil.
- After mowing the lawn, lay down multiple layers of newspapers topped with a final layer of cardboard to secure the newspaper in place. Again, these organic layers will be broken down by the soil citizens.
- Purchase wood chips and pile them at least 6 inches deep. Do not leave any open spaces between the chips where light can reach the grass plants. Remove the chips in the spring. Do not dig them into the soil.
- The next methods are more labor intensive and do not enrich the soil. They merely kill the turf plants.
- Cover the turf with smothering materials such as composite roofing to totally cover the spot.
- Cover the turf with heavy gauge black plastic and pin it down with stakes. Do not use landscape fabric, which is permeable.
The disadvantage to the final two methods is that they can damage existing tree or shrub roots because they cut off the source of oxygen and moisture to those roots.
If you have made the commitment to have less turf, skimming up the lawn with a cutting tool such as a large flat-bladed spade or renting a mechanized sod-cutter will get rid of the plants. The bare soil should be covered with a mulch of chopped leaves to prevent weed seeds from germinating in the early spring.
Tilling up the turf could leave many grass roots to regrow, as well as the seeds from the nuisance weeds.
In the spring, the new bed needs to be spaded up because most turf areas are fairly compacted. Organic materials can be incorporated when spading the bed.
A WSU Chelan and Douglas County Master Gardener column appears weekly in The Wenatchee World. To learn more, visit bit.ly/MGchelandouglas or call (509) 667-6540.