Lawn renovation refers to any procedure beyond normal maintenance (short of soil modification) required to upgrade an existing lawn. A deteriorated lawn is often a symptom of some underlying problem. Failure to identify and correct the exact problem can often lead to further lawn deterioration and the need for repeated renovation. Some of the major causes of turf deterioration include:
When to Renovate
Late summer to early fall is the best time to renovate cool-season lawns. Warm-season lawns are best renovated in late spring to early summer. Attempts to upgrade existing lawns when conditions are not conducive to good growth are difficult at best.
Weed Control
The first step in lawn renovation is the control of undesirable vegetation that competes with newly planted grasses.
Preparation for Seeding
Preplanting renovation procedures are designed to create an environment best suited for the establishment of newly planted grasses. This process includes the following:
Set the rotary or reel mower at the lowest setting, mow, and collect the clippings. Remove all undesirable vegetation, dead grass, thatch, and weeds so that the soil is exposed. (This may not be necessary if a slit seeder is used.) A rake or hoe is ideal for small areas. Several passes with a dethatcher (power raker, vertical mower) is usually the best choice for large areas. If thatch is excessive, it may be necessary to make another pass with a dethatcher after mowing. Both mowing and dethatching reduce plant competition and enhance light penetration for good germination and fast establishment.
Applying Nutrients
Apply needed fertilizer and lime based on soil test results. Hand application is fine for small areas, but a rotary or drop-type spreader should be used on large areas to ensure uniform application.
Preparing a Good Seedbed
In small bare spots, loosen the top 4 to 6 inches of the soil with a rake, hoe, or shovel. Fill in low areas and smooth the surface so clods are smaller than marbles.
Large areas and areas that contain 50 percent desirable grasses are best prepared for seeding by using a piece of equipment (such as an aerator or coring machine) that brings small soil cores to the surface. This will bring soil to the surface with minimal disruption and create an environment for good seed-to-soil contact. Core in several directions, allow plugs to dry, and then pulverize with mower, dethatcher, or chain link fence. Because tines have a difficult time penetrating dry, compacted soils, coring is best achieved when the soil is damp.
Seeding
Bare spots larger than 4 inches in diameter should be planted. Smaller areas tend to fill in naturally, provided the lawn grass is capable of spreading. Tall fescue and perennial ryegrass exhibit a bunch-type growth habit and are incapable of spreading. Choose a blend or mixture that is compatible with the environment and the existing lawn.
To ensure uniform coverage, use a rotary or drop-type spreader, applying half the seed in one direction and the other half at right angles to the first pass. Incorporate seed and fertilizer into the top 1/8 inch of soil by lightly pulling a leaf rake over loosened soil or running a vertical slicer over areas that were just power raked and cored.
A slit seeder, consisting of a vertical grooving seeder and seed box, drills seed to ensure good seed-to-soil contact with minimum disruption. Seed should be drilled in a diamond-shaped pattern. Dry, compacted soils, obstructions such as rocks and trees, and excessive slopes may limit the usefulness of a slit seeder.
Bare areas that are seeded should be mulched to enhance germination.
Plugging
Plugging can be used for those grasses that spread laterally. However it is not recommended for bunch-type grasses such as tall fescue, ryegrass, bahiagrass, and fine fescue. Place plugs on 6- or 12-inch centers, depending on the desired establishment speed. Use a plugging device to remove plugs of soil from bare areas and switch them with plugs collected from healthy areas. Apply a starter-type fertilizer, such as 10 pounds of 5-10-10, per 1,000 square feet.
Broadcasting Large Areas (15,000 square feet or more)
This method is often reserved for bermudagrass. Rototill the recommended amount of fertilizer and lime as indicated by soil test results or apply 75 pounds of lime and 20 pounds of 10-10-10 fertilizer to the area to be sprigged. Spread sprigs over the surface using rates provided in Table 4 for new areas. Press them into the top ½ to 1 inch of soil using an old disk set straight, special planter, cultipacker, or roller. Roll the area to firm the soil and ensure sprig-to-soil contact.
Care After Planting
Keep renovated areas moist with light sprinklings several times a day. As the seedlings, plugs, or sprigs grow, continue to decrease the frequency of waterings while increasing the duration to promote deep rooting. After the third mowing, apply enough water to moisten soil at a depth of 6 inches.
Mow the area using a sharp blade. But continue to severely stunt existing vegetation by mowing short until desirable grasses have germinated and the desired mowing height is achieved. This will reduce the competition for new seedlings.
Fertilize the new seedlings of cool-season grasses using a complete (N-P-K) fertilizer that provides about 1 pound of nitrogen per 1,000 square feet. To determine how much fertilizer to use, divide 100 by the first number on the fertilizer bag. This value will determine the amount of product to be used per 1,000 square feet. Example: A 16-4-8 fertilizer. 100 divided by 16 equals 6.25. Therefore, 6.25 pounds of fertilizer per 1,000 square feet will deliver 1 pound of nitrogen. To enhance establishment, this fertilizer should be applied approximately three weeks after seedlings emerge.
Warm-season grasses can be fertilized every four weeks until coverage is complete. Use a complete (N-P-K) fertilizer that provides about 1 pound of nitrogen per 1,000 square feet. Biweekly applications of a nitrogen-only fertilizer that provides about 1/2 pound of nitrogen per 1,000 square feet may help warm-season grasses fill in more rapidly.
Keep unnecessary traffic off the renovated lawn until it is well established.
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