Rehabilitate a lawn

You've just inherited a horrible account; a real fixer-upper. The lawn has weeds, ruts, low areas and lots of coarse grasses. The owner expects you to work wonders. To make matters worse, you have little information about the lawn's history to help you bring it back to respectability. What to do?

1. Inventory the turf First, inventory the lawn, taking notes as you go. Draw a simple sketch of the property, and place it on a clipboard. Jot down comments about the lawn's condition. You may find, for example, several species of undesirable perennial grasses, that something has thinned the front-yard turf, and the turf is really struggling on the slope on the west side. You can designate each of these identified problem areas with a technique borrowed from landscape designers called a bubble. A bubble is simply a circle, oval or other shape drawn on a piece of paper with a few words penciled in that describe the specific concern in that area (see figure, page 34).

2. Analyze your findings Interpret the findings in the inventory. For instance, the front yard may be thin due to billbugs, and the slope on the west side is causing rapid runoff, probably limiting water infiltration. Whatever the suspected cause of the symptoms-poor infiltration, excess thatch or a pest of some sort-write it in each respective bubble. This analysis will help lead you to solutions.

Analysis may not be simple. It may require you to scout or sample for insect pests or diagnose a pathogenic disease. If you need help, consult written references or get in touch with a Cooperative Extension agent for advice.

Soil testing is another important part of the inventory/analysis phase of rehabilitation. It helps identify "hidden" causes of turf decline. Most soil-testing labs not only provide test results, but also provide recommendations for achieving optimal pH, organic-matter content and nutrient levels.

3. Fix existing problems Once you've identified the causes of the poor turf, take steps to fix the problems. Correcting certain problems-for example, poor drainage-early in the rehabilitation process is easier than waiting until after you've planted new grasses. Now is the time for you to remove thatch or prune trees to increase air circulation and light penetration.

However, in some cases, the best time to treat the pest or problem is not when you're diagnosing the lawn. For example, if you take over an account in April, and you note white grubs in the site inventory, you should simply mark your calendar for appropriate treatments later in the season.

4. Prepare to overseed * Remove undesirable weeds from the lawn. If more than 50 percent of the lawn is infested with grassy weeds, you'll need to completely renovate and spray the entire lawn with a non-selective herbicide such as Roundup or Finale. In most situations, however, only partial renovation is necessary. Use a selective broadleaf herbicide to control broadleaf weeds and non-selective herbicides to spot-spray patches of perennial grassy weeds. Be sure to read the herbicide label for guidelines on how soon you can seed or sod following the application.

* Reduce competition from the existing turf. The remaining desirable turf will compete with the new grass seedlings for water, sunlight and nutrients. To lessen this competition, scalp the existing turf. Mowing at half the normally recommended mowing height will open the turf canopy and stress the existing grass plants slightly. This reduces their competitiveness and creates a more favorable establishment environment. Some operators use a plant growth regulator (PGR) at this point. Such an application, though not absolutely necessary, will provide additional suppression of the existing turfgrasses.

* Cultivate. Follow the close mowing with cultivation. The key concept in regrassing is seed-to-soil contact, which helps ensure young seedlings will successfully become established. The less desirable the existing turf is, the more you need the newly planted seed to develop into a solid stand, so the more extensively you need to cultivate (to create more seed-to-soil contact). In other words, match the type and extent of cultivation with the severity of the problem. Slicing and slit seeding are less disruptive than aeration and power raking, but create a poorer seedbed. If the need is great, aerate in several directions. This will help provide many sites for seed to become established. When power raking, several passes may be necessary. However, excessive power raking can be harmful. It is important to leave a small amount of stubble or some sturdy grass plants to prevent erosion of the seedbed and to shade new seedlings during establishment.

* Choose the overseeding varieties. Obviously, you should avoid overseeding turf with new varieties or species that will clash with existing turfgrasses. Thus, warm- and cool-season turfgrasses should not be mixed, and, depending on what the customer will accept, it may be best to avoid certain cool-season mixes. Check with the land-grant university in your state or the National Turfgrass Evaluation Program (NTEP) for the latest data on performance of turf cultivars.

Be sure you choose varieties suitable for the site. For example, look for varieties that are resistant to diseases present at the site or in the area. If shade contributed to the original turf's decline, look for shade-tolerant varieties.

* Determine the seeding rate. Once you've prepared the seedbed, calculate the size of the area you'll seed. Measure the area of the "bubbles" of poor, thin turf that you noted in the site analysis/inventory. Knowing the square footage you will overseed, you can determine the amount of seed you'll need (see box, "Overseeding rates," below). Adjust the seeding rate according to the need-badly thinned lawns need more seed.

5. Seed or sod the lawn * Seeding. Getting the seed into the ground is the next step. Use the fastest method to apply the seed without sacrificing seed-to-soil contact or distribution uniformity. The size and weight of the seed may dictate the equipment you use. Even the gentlest wind can carry small, light seed off site if you apply it with a broadcast spreader. The seeding pattern of large, heavy seed, by contrast, is not as easy to distort. Therefore, lighter seeds work best with a slit seeder or drop spreader, which limits the movement of the seed to non-target areas. You will achieve the best seed-distribution pattern by making two half-rate applications in opposing directions. With this approach, less potential exists for skips and gaps in the pattern.

After seeding, drag or roll the seeded ground. Rolling is acceptable for most soils, but should be avoided with high-clay soils, which are prone to compaction. You also can use a section of chainlink fence or some similar material for dragging.

* Sodding. If you decide to use sod, lay it as soon as possible after cutting. Butt the strips together lightly with no overlapping, and stagger them in a brick-like pattern. Avoid stretching the sod, because it will shrink after drying. Lay sod lengthwise across the face of slopes, rather than up and down. Peg or stake the pieces of sod on slopes to prevent slippage.

When you sod areas within existing turf, the edge of the sodded area will create a "lip" if you don't accommodate the change in grade created by the thickness of the sod. Be sure to address this by lowering the grade an inch or so where the edge of the sod will lie, or by applying a small layer of soil along the edge of the sod to create a gradual slope.

Roll the sodded area as soon as possible to ensure good soil-to-sod contact. Maintain a moist surface, but do not create a soggy sod/soil interface. Continual saturation will increase weeds and diseases and will extend the time required for rooting. Keep traffic over the area to a minimum for 3 to 4 weeks.

6. Aftercare * Water. Instruct the homeowner to water frequently and lightly for the first 2 weeks or so after seeding. Then, gradually reduce the frequency and increase the duration of the irrigation to encourage a more extensive root system. A "door hanger" can help remind homeowners how and when to water. Using printed literature such as this will project a professional image of your company and increase the likelihood that the customer will be satisfied.

* Fertilizer. Apply starter fertilizer no sooner than 3 weeks after the initial seeding to encourage rapid establishment of the new seedlings. Fertilizing at seeding time will encourage growth of the existing grass plants, which will increase competition and reduce establishment.

* Weed control. Crabgrass is likely to germinate along with the desirable turfgrass. A new product-BASF's Drive (quinclorac)-offers a possible solution. You can apply Drive anytime before the new turfgrass seedlings begin to germinate. Used in this manner, it will provide post-emergence control of young (pre-tiller) crabgrass plants as well as residual control, without harming the new turf. Drive controls several other weeds in seedling turf as well.

Another option for certain weeds is siduron (sold as Tupersan), a pre-emergent that you can use on many cool-season turfgrasses at the time of seeding or soon thereafter. Check the label for specific tolerances. As the young turf grows, it will reach the size at which it will tolerate typical herbicide use (typically after 4 to 6 weeks), such as broadleaf products and pre-emergents. If necessary, use such products to reduce competition from weeds. Be sure to check the label of the product you wish to use to confirm whether the young turf is of sufficient size to safely tolerate the application.

7. Follow up with good maintenance Finally, consider the original cause of the decline and make changes accordingly. For example, if improper mowing and watering techniques were the culprit, instruct the homeowner in the proper routine maintenance of the lawn (unless, of course, you are performing the maintenance yourself). If the lawn was thin due to shade, lower the maintenance intensity to allow for the shady conditions. Remember, good lawn care is a partnership. It takes you as a troubleshooter and provider of good care as well as the homeowner's attentions to produce a high-quality lawn.

1. Identify the cause of the turf decline 2. Change cultural practices/correct existing problems: * Treat for weeds, insects and diseases, as necessary * Correct drainage problems * Prune for improved light penetration 3. Test soil and modify, if necessary 4. Mow closely, suppress growth of existing turf 5. Cultivate with a power rake, aerifier or vertical mower 6. Overseed with improved cultivars 7. Provide good aftercare

The following ranges include low to high rates (in pounds per 1,000 square feet) for overseeding: * Kentucky bluegrass: 1.5 to 3.0 * Perennial ryegrass: 2 to 4 * Fine fescue: 2 to 4 * Tall fescue: 9 to 10

Vegetative establishment rates are: * Bermudagrass: 1 bushel of sprigs, or 2-inch plugs in 6- by 6-inch spacing (requires 55 square feet of sod per 1,000 square feet). * Zoysiagrass: 2-inch plugs in 6- by 6-inch spacing (requires 55 square feet of sod per 1,000 square feet).

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