A summertime tune-up for your yard

The early days of the growing season were so promising—your yard was lush and green, with no bald spots or weeds to be seen. But now, with the dog days of summer upon us, your lawn is looking less and less like an inviting carpet to lounge and play on. If that sounds familiar, your yard might be suffering from some of the typical problems listed below.

But before you take any corrective action, raise the cutting height on your mower one notch or a half-inch. By not cutting your grass too short, you'll allow your lawn to better survive summer heat—taller grass blades have longer roots and provide more shade to retain moisture.

Thin, weak, or yellowish lawn. Nitrogen-rich fertilizer is the usual cure for this problem. But the cause can also be too little iron or magnesium, especially in the West, where alkaline or high-pH soils are common.

Iron sulfate or iron chelate will turn the lawn green within two days if it's low on iron. Be especially sure to keep iron sulfate on the lawn, since it can stain paving. If the lawn doesn't respond, mix 2.5 tablespoons of Epsom salts into a gallon of water and spray it over a test area. The area should turn green within two days if the problem was too little magnesium.

Dead spots. Most of these withering areas are caused by dog urine, spilled gasoline, or spilled fertilizer rather than by disease. Soak the area with water to wash the salts or chemicals into the soil and minimize their damage. Next, cover the area with a layer of new soil followed by new grass seed and starter fertilizer. Remember to keep the area well watered.

Mushrooms. These annoying fungi typically—and, it seems, magically—appear after a rain and often indicate dead tree roots or decaying wood. You can't eliminate them without removing and replacing the soil in which they live, but you can mow or rake them away as they appear.

Water runs off and won't soak in. This situation is caused by poor or compacted soils or by sprinklers that apply water faster than the soil can absorb it. Sloping ground worsens the problem.

Sprinkler heads that water more slowly are one possible solution. Aerating the lawn, which involves extracting narrow cores of soil, can also boost water absorption and reduce runoff. Top-dressing the area with peat moss will also help.

To avoid common watering mistakes, learn the ABCs of irrigation.

Moss. Too much shade is a prime culprit. Other causes include compacted, infertile soil and soil acidity, or pH, that's too high or low.

If a soil test shows low pH, adding limestone in the form of palletized (powdered) lime will help. (Your local cooperative extension system office can test the soil for you.

You can also apply moss killers, which contain a form of iron sulfate to burn the moss. But unless you address the underlying problem, the moss will return.

Thinning trees at least annually will let in more light and help the tree when done correctly. (Learn how to prune trees.) Removing or mulching fallen leaves also helps, as does mowing grass beneath trees slightly higher and fertilizing it a bit less. Also consider replacing grass beneath trees with wood chips or other ground cover.

Essential information: Use our exclusive interactive tool to identify and control the weeds, pests, and diseases that are damaging your lawn. If you need any new geat for your yard, read our buying guides to mowers and tractors and string trimmers.