By Jeff Rugg Creators Syndicate Inc.
Question: We live in the south and have a zoysia lawn. It feels spongy when we walk on it. We were told that the straw grows. It costs a lot to core a lawn. Is it very harmful to the lawn? Is there a cheaper way to get rid of it?
Answer: The straw consists of above-ground roots and stems of a grass plant. It’s not the brown blades of grass that are left over from the mowing; it looks like a mass of threads that are usually dark brown in color.
Most of the time, the roots and stems should grow in the ground, but for some reason they grow in the ground. As the straw thickens, it prevents water from entering the ground. Grass roots cannot grow in the ground without water, so they die off and only let the roots grow in the straw. Half an inch or less of straw is usually fine, but if the lawn felt spongy to the touch as you walk, I would suspect that the layer of straw on your lawn is more than an inch thick. In this case, a single coring won’t repair your lawn. You need a long-term strategy.
Straw inspection is often done when grass is actively growing and filling in the bald spots. The northern cool season grasses are removed in the fall, and the warm season grasses (like your zoysia) should now be removed between June and July. Since the grass leaves and crown (the base of the plant) grow on top of the straw, coring will no doubt ruin the look of your lawn.
As part of your strategy, you need to figure out why the straw is growing. Is the soil compacted? Is the soil pH too high or too low? Is the lawn flooding? Is the irrigation system running too long and drowning the grass roots trying to grow in the ground? Some grasses, like your Zoysia, grow more straw than others.