Lawn renovation refers to any procedure beyond normal maintenance required to upgrade an existing lawn. Renovation generally takes place on a small scale in isolated areas of the lawn. Bare spots larger than 4 inches in diameter should be replanted. Deterioration of the entire lawn may require reestablishment. A deteriorated lawn is often a symptom of some underlying problem. Some of the major causes of lawn deterioration include:

• Planting a turfgrass that is poorly adapted to the site (this may result from a gradual change, such as increased tree canopy).

• Overwatering, overfertilizing, or mowing too low.

• Poor drainage, heavy shade, or compacted soil.

• Improper nutrient balance or low pH.

• Excessive thatch buildup.

Before renovating, identify and correct the problems that may have caused the deterioration. Otherwise, renovation will be an ongoing process.

To achieve good germination and fast lawn establishment, remove weeds and prepare the soil before overseeding. Do a soil test in the area to be renovated and follow recommendations for nutrients and pH. If total renovation of an area is needed because of severe damage or takeover by weeds, cover the area with a black plastic sheet for 7 to 10 days to kill most plants, including weeds. Any plants not killed will have to be manually removed. In bare areas, loosen the top 4 to 6 inches of the soil with a rake, hoe, shovel, or rototiller. Fill in low areas and smooth the surface so that any clods are smaller than marbles. If the area is to be reseeded, add compost before tilling to enhance water retention and speed germination. It is also possible to renovate small areas by coring and reseeding.

1. Remove as much extra vegetation as possible from the area to be overseeded. Use a rake to remove thatch, weeds, and leaves. It is important to remove the roots of weeds too, to prevent them from regenerating. Weeds with underground shoots are harder to control and may need to be tilled under. Making several passes with a power rake is usually the best choice for cleaning up large areas.

2. Apply a complete (N-P-K) fertilizer to the soil. In small areas, hand application is acceptable. In larger areas, use a rotary or drop spreader to ensure uniform distribution.

3. Use a rake to loosen the soil between existing plants as much as possible. If the soil is very dry, moisten it to improve penetration by the rake. In large areas, use a core aerifier to bring the soil to the surface. After aerifying, let the plugs dry, then pulverize with a power rake or by dragging a section of chain-link fence over the area.

4. See Table 3 for correct seeding rates. To ensure uniform coverage of seed, use a rotary or drop spreader, applying half of the seed in one direction and the other half at a right angle to the first pass.

5. Keep the overseeded areas moist by sprinkling lightly several times a day. As seedlings grow, water less often but more deeply to promote deep rooting.

Late summer to early fall is the best time to renovate cool-season lawns. Seedlings can survive the heat and drought stresses of summer better if they can establish themselves the previous fall and winter. Warm-season lawns are best renovated in late spring to early summer. Attempts to upgrade existing lawns when conditions do not favor good growth are unlikely to succeed.

Seeding is recommended for turfgrasses with bunch-type or slowly spreading growth habits. These include tall fescue, Kentucky bluegrass, ryegrass, bahiagrass, and fine fescue. See Table 3 for correct seeding rates. To ensure uniform coverage, use a rotary or drop spreader, applying half of the seed in one direction and the other half at a right angle to the first pass. Incorporate seed into the top 1/8 inch of the soil by lightly pulling a leaf rake over loosened soil or by running a vertical slicer over areas that have been aerified by coring. Adding a light covering of weed-free straw will help protect slopes from erosion and help retain heat and moisture.

Plugging can be used for turfgrasses that spread laterally, including bermudagrass, zoysiagrass, St. Augustinegrass, and centipedegrass. Place plugs as close together as practical, considering 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.

Broadcast sprigging large areas (15,000 square feet or more) is often reserved for bermudagrass. Use a rototiller to incorporate the amount of fertilizer and lime recommended by soil tests. Spread sprigs over the surface using rates provided in Table 3. Press the sprigs into the top 0.5 to 1 inch of soil. Roll the area to firm the soil and ensure good sprig-to-soil contact.

Keep renovated areas moist with light sprinklings several times a day. As the seedlings, plugs, or sprigs grow, decrease the frequency of waterings while increasing the duration to promote deep rooting. After the third mowing, water to a depth of 6 inches.

Mow the areas as you normally would, using a sharp blade. Keep weeds pulled or cut very short until desirable turfgrasses have germinated and the desired mowing height is achieved. This will reduce the competition faced by new seedlings.

To enhance establishment, fertilize the new seedlings of cool-season turfgrasses. A complete (N-P-K) fertilizer that provides about 1 pound of nitrogen per 1,000 square feet should be applied about three weeks after seedlings emerge if using soluble inorganic fertilizer. An organic fertilizer, which will release nitrogen and other nutrients more slowly, needs to be applied at time of planting.

Warm-season turfgrasses can be fertilized every four weeks until turfgrass coverage is complete. Use a complete (N-P-K) form of fertilizer that provides about 1 pound of nitrogen per 1,000 square feet. Applying a nitrogen-only fertilizer that provides about 0.5 pounds of nitrogen per 1,000 square feet every two weeks may help warm-season turfgrasses fill in more quickly. Keep unnecessary traffic off the area until reestablished to prevent damage to the seedlings.

In bermudagrass lawns, overseeding with annual or perennial ryegrass will help to maintain a green color and protect the dormant warm-season turfgrass during the cooler months. Occasionally, zoysiagrass and centipedegrass are also overseeded, but it is generally not recommended. It is important that the warm-season turfgrass be healthy before overseeding so that it can withstand the rather harsh cultural practices and competition from cool-season turfgrass associated with overseeding.

Timing

Overseeding should take place in late fall, two or three weeks before the expected first frost or when the soil temperature drops below 75ºF. In the piedmont, this is usually September 15 through October 15. Plant one to two weeks earlier in the western part of the state, and one to two weeks later in the eastern part of the state.

The transition back to warm-season turf growth will begin in the spring, when night air temperatures begin to reach 60ºF and the warm-season turfgrass begins to break dormancy. Regular maintenance practices for the warm-season turfgrass, competition from the warm-season turfgrass, warm temperatures, and disease should eventually force the overseeded species out of the lawn in the spring. However, overseeding for several consecutive years may result in gradual decline of the warm-season lawn and greater encroachment of the cool-season species. Therefore, it is important to establish a healthy warm-season lawn before considering overseeding.

1. Prepare for overseeding by closely mowing the warm-season turfgrass.

2. Thin the turf, especially hybrid bermudagrass, with a power rake to improve seed placement near the soil. Centipedegrass and zoysiagrass are slow to recover from injury, so only lightly rake the surface on these lawns and remove the clippings.

3. Apply a complete (N-P-K) fertilizer with a ratio of 1-2-2 based on 0.25 pounds of nitrogen per 1,000 square feet. Do not stimulate continued growth of the warm-season turfgrass by applying too much fertilizer or applying fertilizer too early. When possible, use a rotary spreader to ensure uniform application.

4. Choose a seed species. Annual and perennial ryegrasses are the major overseeding species. They are both quick to establish and relatively inexpensive. Newer varieties of perennial ryegrass are more heat- and disease-tolerant.

5. Use a spreader to apply the seed at 5 to 10 pounds per 1,000 square feet. Higher rates will produce denser, lusher lawns but will create more plants to remove in the spring.

6. If possible, top-dress the lawn with a light layer of sand or compost to improve seed-to-soil contact.

7. Water two to three times daily until the seedlings begin to emerge. Apply enough water to moisten the surface but not enough to cause movement of the seed. As the seedlings emerge, water only once per day. Once the seedlings are established, water only when necessary to supplement rainfall.

8. Begin mowing two to three weeks after emergence. Do not remove more than one-third of the leaf blade in any one mowing. Maintain a mowing height of 1.5 to 3 inches.

9. Fertilize every four to six weeks with 0.5 pounds of nitrogen.

10. In the spring, when night air temperatures are regularly above 60°F, mow the overseeded grass closely (1 to 1.5 inches) to promote growth of the warm-season turfgrass.

11. Do not fertilize until the warm-season turfgrass has returned to its green color.

The key to successful organic lawn care is to strive to prevent problems rather than treating them after they appear. For success with your organic lawn, choose a sunny, well-drained site, and protect and prepare the soil as recommended. Select a turfgrass that will grow well in your area and wear well for the uses intended, and then water and fertilize appropriately, mow on schedule, and inspect the lawn frequently to spot any problems early.

It is important to recognize that just because a product is labeled as organic or comes from a natural source does not mean that it poses no threat to the environment or to people, pets, and wildlife. To prevent water pollution from organic fertilizers, follow recommended rates for application and sweep fertilizers off paved surfaces. Nitrogen and nutrients from any source, organic or otherwise, should be kept out of streams and other nearby waterways.

Some organic pesticides are very toxic and should be stored in a locked or secure place. If you use such products, always read and follow product labels. The “organic” products on the market change frequently. No brand names are listed in this publication because new products become available each year and others are taken off the market or are not available in every location.

Consult your local N.C. Cooperative Extension center for current information.