A restoration allows you to improve your lawn without removing the existing turf. While restoring your lawn is not nearly as labor intensive as removing all of your turf and starting over, it will still require several weekends of work. In this section, each step of a lawn restoration is described, some of which are essential and others optional. In most parts of North America, the best time to begin restoration is late summer or in fall, although adjusting pH and dethatching can be done in the spring to prepare for a fall restoration. You will see some improvement in a restored lawn during the season in which you begin, but you will need two or three growing seasons to see dramatic progress.

1. Remove Thatch and Weeds
When beginning a lawn restoration, the first step is to remove any thatch buildup--even low levels that would otherwise be acceptable. Unless you can expose the soil between the old grass plants, the steps that follow will have poor results. While you're at it, make a note of weed colonies and remove the worst of them with a grape (grubbing) hoe before proceeding to Step 2.

The best time to dethatch is when your lawn is thriving - not when it's stressed in the heat of summer or cold of winter. To begin, set the height adjustment on your mower to cut the grass about 1 inch high, essentially half its normal mowing height. Mow the entire lawn. Short grass will make dethatching and surface preparation easier. It will also improve seed germination rates because more seed will make contact with the soil and seedlings will have greater exposure to the sun.

The easiest way to remove thatch from a lawn that is over 3,000 square feet is with a power rake, or vertical mower (a machine with vertical instead of horizontal cutting blades), which should be available at rental stores. For smaller lawns or lawns with thin, 1/2- to 1-inch layers of thatch, a manual thatching rake will do a satisfactory job.
When using a vertical mower to remove average amounts of thatch and to scarify the soil, set the blades to cut 1/8 to 1/4 inch into the soil. Make several test passes on an inconspicuous area of your lawn to judge how much thatch (and turf) will be removed. If too much or too little is removed, raise or lower the blades accordingly. The spacing between blades can be adjusted on some machines, but this is difficult to do and so is best done by the rental store staff. The blade spacing for Bermudagrass and zoysiagrass is 1 to 2 inches, while the spacing for bahiagrass and St. Augustinegrass is 3 inches. Most rental store owners will know the optimum settings for the grasses grown in your area.

When using a vertical mower to dethatch, make several passes over the lawn in perpendicular directions. It is important to be thorough. Remove the thatch you pull up after each series of passes and add it to your compost pile. When you have finished dethatching, remow your lawn to a height of 1 inch. For more information on manual thatching rakes, power-rakes, or vertical mowers, see "Appendix I."

On a lawn with thick thatch (more than 1-1/2 inches), you may need to partially remove the thatch and allow the lawn to fully recover before the next dethatching session. Removing too much thatch all at once can do more harm than good. The rule of thumb is to remove what you can without tearing up holes of more than a couple of square inches in live turf. This may not be possible on lawns with very thick thatch--more than 2 inches. In that case, your lawn may not be salvageable and may need to be replanted from scratch. See "Starting a New Lawn from Scratch."

2. Fill depressions and level bumps
While you are dethatching your lawn, check for bumps and depressions. These may have been caused by poor grading, uneven settling, or the decomposition of buried tree stumps, logs, or roots. Mark any irregularities with latex spray paint so you can find them easily when you are ready to level them.

To level small bumps, raise the sod with a sharp spade and remove the necessary amount of soil beneath it. Cut out at least a 2 by 2-foot section of sod. If you lift smaller patches of sod, they will likely dry out and die. While the soil base is exposed, mix in some compost and fertilizer. Watersoak the area using a hose and press the sod back into place. Keep the area watered to prevent lawn brownout.

Slight depressions can be smoothed over by topdressing: applying to the surface a combination of topsoil and compost. A wide landscaping rake is the best tool for this job. When handling larger depressions--those more than an inch or two deep and several square feet in area--raise the sod; fill the depression with a mixture of soil, humus, and fertilizer; replace the sod, and press it in place. Be sure to keep repaired areas moist, or the edges will dry out and turn brown.

3. Adjust Your Soil's pH

Before applying anything, it is best to test your own soil or obtain test results from a professional testing service. If your soil test shows that the soil pH is low, add lime according to the test recommendations. If you did your own pH test and thus have no recommendations to go by, use the accompanying charts to determine how much lime to apply. If you're unsure of your test results, be conservative. Too much of an amendment can be as detrimental to your lawn as none at all.

Lime amendments come in various forms, from ground oyster shells to liquids. Agricultural ground limestone is the preferred type because it is readily available and can be safely, easily, and accurately applied with a drop or rotary spreader.
There are two types of agricultural ground limestone: dolomitic and calcitic. Both contain calcium carbonate, a grass nutrient, and a neutralizer for acidic soil. Dolomitic limestone contains magnesium, another important nutrient, as well as calcium carbonate. Use dolomitic limestone if your soil is deficient in magnesium. Calcitic limestone does not contain magnesium, making it more appropriate if your soil is already high in magnesium. However, adding dolomitic limestone to soil already high in magnesium has not been shown to cause lawn problems.

For faster results, choose a finely ground limestone. Fine grinds begin to correct the soil pH faster than coarse grinds. Coarsely ground limestone acts slowly and is better suited for use once you have raised your pH to a desirable range. You can tell fine lime from coarse if you understand the information on the package. The higher the percentage of ground lime that passes through the finer sieves, the finer the grind. Sieves are graded by number; the higher the number the smaller the sieve holes. Look for a product stating that 50 percent or more of the ground limestone will pass through a number 100 sieve. Caution: Fine grinds can burn grass. Check instructions on the packaging.

One more thing to keep in mind when buying lime is its relative purity. Liming materials are rated according to their Calcium Carbonate Equivalent (CCE). A CCE rating of 100 is equal to pure calcium carbonate; less than 100 indicates less neutralizing ability than calcium carbonate. Account for the CCE when figuring how much lime to apply to your lawn. If the CCE of the product you purchase is 80 and your soil test recommendations assume a CCE of 100, you will need to increase the recommended application rate by 20 percent.

As you can see from the chart, the more clay and organic content in your soil, the more lime you will need to correct the pH. Sandy soils require less lime to raise pH. If you need to add more that 40 pounds of lime per 1000 square feet to correct your pH, do it in two or more applications. And don't apply lime with fertilizer mixed in the same spreader. The resulting chemical reaction will release the nitrogen you want for your grass into the air. After spreading lime, water the lawn to wash the particles off the grass leaves and into the soil.

To lower the pH, add sulfur according to you soil test recommendations. Sulfur amendments are also available in the form of compounds, such as ammonium sulfate. These compounds can be used in place of elemental sulfur, but they can burn turf if used in excess. See amendment packaging for details on amounts that can be safely applied to turfgrass.

If you are relying on your own test kit and not a professional test, follow the recommendations in the chart. Sulfur acts within one month to lower soil pH. To avoid applying too much, don't try to make your correction in one application. To meet recommended amounts, make several surface applications a few weeks apart and water the grass after each application.

4. Add Nutrients

When restoring a lawn, apply the fertilizer recommended by the results of your soil. Use a slow-release fertilizer, and avoid putting down more fertilizer than you need. Adding too much nitrogen can cause rapid growth and a thinning of plant cell walls, which makes grass more susceptible to disease. The excess fertilizer may also leach and eventually find its way into waterways, polluting them.If you did not test your soil, apply a slow-release fertilizer with an Nitrogen-Phosphorus-Potassium ratio of 3-1-2. Apply about 1/2 pound of nitrogen per 1,000 square feet of lawn. (See "Turf Fertilization" for more on fertilizer types.)

5. Build Organic Matter and Microbe Numbers

The right dose of fertilizer won't help much if your soil does not contain an adequate population of microbes, you need billions of these microscopic organisms per handful. Microbes not only digest grass clippings, dead grass roots, and stems, but they also make their nutrients available to living grass plants.

To have a thriving microbe population, your soil must contain 2 to 5 percent organic material. A topdressing of compost mixed with topsoil followed by aeration will eventually incorporate some organic matter into the soil without disrupting the lawn.
When top dressing your lawn, apply about one cubic yard, which is 100 pounds of a 40-60 mix of topsoil and compost, per 1000 square feet. Topsoil is available from most nurseries and landscape centers. Be sure it has a dark, rich brown color and feel and that it has not been diluted with lighter-colored subsoils. Compost can be obtained from several sources. Many towns make compost available to residents at little or no cost. They make compost from the leaves, grass, and brush that residents haul to the dump. The compost should be screened to 1/4- or 3/8-inch particles, and it should be free of in organic materials, such as shreds of plastic leaf bags. Its moisture content should be 30 and 50 percent. Any drier, and the compost releases a lot of dust as it's being worked; any wetter, and the material tends to clump and not mix well with soil. Compost is also available from nurseries and landscape centers. Better yet, make your own.

6. Aerate Your Lawn

Aeration, also called core cultivation or aerifying, is an important part of any lawn restoration program. It allows grass roots to deeply penetrate the soil, helps fertilizer and organic matter get to roots, allows oxygen to reach the roots, and makes it easier for water to soak into the soil. Simply aerate once in the fall. Avoid aerating during dry summer months because you may damage an already stressed lawn. Also, avoid periods when weed seeds are prevalent, as that could cause weed infestation.
There are several types of aerating tools. Manual aerators allow you to do small areas a little at a time and to aerate corners and other tight areas that are difficult to reach with large equipment. You supply the power for these tools by pushing the hollow cylinders or corers into the turf - much as you would push in a spade. The tool cuts a plug, or core, that is extracted and deposited on the lawn the next time you push it into the turf. Small power aerators work similarly and are available at rental stores. Some machines use a rotating tillerlike action that pushes the corers into the soil and extracts small plugs, as the machines pull you forward. These lawn mower-size machines will fit into a full-size station wagon, mini-van, or pickup truck and they require two people to transport them.

Avoid aerators that only poke holes in the lawn without removing plugs because they are of less value to your lawn. The largest aerators will require a truck and several helpers to transport them but do a better job. With these machines, the corers are vertically plunged into the turf to extract a sizable plug. You may opt to have a pro tackle this job.

Aerators penetrate your lawn best when the soil has been moistened by rain or watering; so, unless it rains, water your lawn the day before aerating. When aerating, make several passes in several directions over every square foot of lawn. Next, break up all the plugs extracted by the aerator with the back of a rake or by dragging a metal mesh doormat or section of chain-link fence over the plugs to spread the soil. You can also mix the soil from the plugs with the topdressing you added in Step 5. Then water the lawn thoroughly.

7. Prepare the Surface and Overseed it

In the North, the best time to overseed is in late summer and the early fall, although you may also try this technique in early spring. Starting then gives the young grass plants a better chance to germinate, establish strong roots, and store food needed for a head-start in the spring. In the South, the recommended time to overseed is spring or early summer.

Before you begin, choose the seed that's best for you based on the information in the section, "Choosing the right Grass." Be sure to select one of the new varieties bred to withstand the stresses your lawn faces. Then use the table "How Much Seed to Use When Overseeding" to help you estimate how much seed to buy.

You have several tool options for spreading seed evenly and at the recommended rates. They include your own hands, handheld and walk-behind spreaders, and slit-seeders, which are power machines that cut shallow slits in the soil and sow seed at the same time. Available at many rental stores, slit-seeders are the preferred tool, especially if you were not able to remove all thatch prior to overseeding. (See Appendix I for more details on these tools.)

If you will be spreading seed by hand or with a spreader, first use a thatching rake to roughen the exposed soil to a depth of 1/2 inch. Set the spreader to deliver the seed that's recommended by the seed producer for seeding a new lawn. If you were not able to remove all thatch, sow a little extra seed. Similarly, the higher the percentage of weeds in your lawn, the more seed you should sow. For sowing grass seed, the recommended approach is to apply seed to the edges of the area you are sowing first. Then divide your seed and apply half while walking in one direction, the other half while walking in a perpendicular direction. Spread extra seed on bare areas, lightly cover the seed with a mixture of compost and topsoil; then spread more seed on top.

Finally, follow up by rolling all seeded areas with a water-weighted roller that is one-third full to press the seed into the soil. These steps will help prevent the seed from drying out rapidly and consequently improve germination rates.

If you have a lawn with grass that spreads by stolons (aboveground runners), such as Bermudagrass, St. Augustine, zoysia or buffalograss, you may introduce new grass plants by inserting plugs rather than seed (see "Starting a Lawn from Scratch").

8. Care for Young Plants

Your work to this point will have been in vain if you don't care for the young grass plants as the seeds germinate and begin to grow. The most critical need is to apply water at least twice a day, assuming no rain. If the soil is allowed to dry out, the seedlings won't germinate or will soon wither and die. To maximize the germination rate, soak your lawn on the same day you sow the seeds. On the next day, assuming no rain, lightly sprinkle or mist the lawn for about 5 minutes morning and afternoon. Be sure you have moistened the soil to a depth of one inch. Keep the overseeded lawn moist until the young grass plants are 2 inches tall by repeating a light watering every day after periods without rain. This will take 4 to 6 weeks. When the grass is 2 inches tall, resume normal watering patterns. For tips on setting up a convenient, low-cost watering system, see "Starting a Lawn from Scratch."

If the weather is dry or warm, spread a layer of hay mulch to protect the seed from the drying effects of the sun and wind. Use clean mulching straw that's free of seed. Evenly spread about 100 pounds per 1000 square feet. Avoid putting down a heavy layer that would inhibit grass growth.

Begin mowing once the new grass reaches 2 inches. Use a sharp blade; a dull one may tear up young grass plants. Otherwise, stay off the seeded areas except to fertilize once more. If needed, apply the rest of the fertilizer as recommended by your soil test, or apply a second dose of 1/2 pound of nitrogen per 1000 square feet six weeks after germination.

Choose a region: