The weeds in your lawn are trying to send you a message about your soil. You can shush them temporarily by killing them year after year, but until you pay attention to what they are trying to tell you and take action to correct the underlying problem, they are going to keep coming back.
The first step is to properly identify the weeds. Everyone knows dandelion, but there are other common lawn weeds you may not know. The library has many weed identification books or an internet search for “lawn weed identification Wisconsin” will help.
Weeds proliferate in your lawn as a result of soil compaction, too low or too high fertility, poor drainage, too acid or too alkaline soil pH, excessively wet or dry soil, or cutting the grass too short.
Weeds found in compacted soil include plantain, cress, chickweed, mustards, clover, bindweed and dandelion. Overly acidic soils invite plantain, sorrel, cress and moss. Soils with poor drainage encourage moss, spurge, chickweed, knotweed, crabgrass, violets and ground ivy. Soils of low fertility welcome ragweed, thistle, plantain, dandelion, knotweed, crabgrass and clover. Overly fertilized soils lure foxtail, dandelion, purslane, pigweed, knotweed and lamb’s quarters. Dry, sandy soil produces sorrel, thistle, speedwell and pigweed.
You’ll notice some overlap in the list. Weeds are opportunists that can adapt to many situations. In addition, your lawn may have more than just one problem. For example, compacted soil, poor drainage and high acidity commonly go hand in hand.
To correct compacted soil, rent an aerator or hire a lawn service to aerate for you. The machine looks similar to a rototiller and as it is pushed across the lawn, hollow spikes dig in and toss out plugs of soil, allowing air, water and fertilizer to enter. The plugs disintegrate after a few rainfalls. Aeration should be done every one to two years depending on the severity of the compaction.
If weeds are telling you that your soil is overly fertile, you’ve probably been using a synthetic fertilizer. Ease off on fertilizing.
Setting the lawn mower blade to 3 – 3 ½ inches will help grass develop deep, drought-resistant roots that will make for a healthier lawn that can compete successfully against weeds. The taller grass also shades weed seeds and prevents them from germinating. Allowing grass clippings to remain on the lawn provides free nitrogen fertilizer and improves soil conditions, suppresses lawn diseases and reduces thatch and crabgrass.
A soil test can tell you exactly what to add to correct the pH of your lawn if it is too acidic or alkaline, usually lime to raise the pH and sulfur to lower it. Spreading a quarter inch of compost across the lawn is an easier way to naturally correct the pH. Compost will also help correct problems with both poor drainage and overly dry soils.
Fall is a great time to overseed bare spots in your lawn. Leaving them bare allows all manner of lawn weeds to jump right in.
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