Lawn Management

Lawn Maintenance
Adapted from the University of Massachusetts and Ohio State University, 1999 2006

A healthy, established lawn is able to compete with many weeds and resist a certain amount of disease and insect attack, as well as drought. You can maintain a healthy lawn with proper fertilizing, liming, watering, and mowing techniques.

Fertilizer
Fertilizer applications should be based on soil tests. Use a fertilizer with percentages of nitrogen, phosphorus, and potassium in a ratio to correspond to your soil test results.  Generally, a 3-1-2 or 4-1-2 is recommended for established lawns. The ratio need not be exactly 3-1-2, 4-1-2 or 5-1-2. For example, 24-6-6 analysis approaches a 4-1-2 ratio, and a 10-3-7 grade is close to a 3-1-2 ratio. Substitutions of this type can be made without concern.

Amount: The amount of fertilizer to apply is based on the percentage of nitrogen, the first number in the analysis. For example, a 100 pound bag of 10-5-5 fertilizer contains 10 lbs of nitrogen (10% x 100), 5 lbs of phosphorus (5% x 100), and 5 lbs of potassium (5% x 100). No more than 3 to 4 lbs. of nitrogen (total amount of nitrogen actually in the fertilizer) should be applied to 1000 square feet of most lawns in a given year. Less should be used if clippings are left on the lawn. Excess nitrogen promotes lush, tender growth that is susceptible to disease, and results in higher maintenance needs.

Applying: Calibrate your spreader to apply the proper amount of fertilizer. Do not apply fertilizer when grass leaves are wet. Water the lawn immediately after fertilizing to wash the fertilizer off the foliage and to prevent 'burning' the plants (unless the directions on the bag state otherwise).

Timing: Fertilizing at the wrong time of year can lead to problems. For the best lawn health and appearance, three applications of 1 pound of nitrogen per 1000 square feet is recommended. The first application should be in April or May, even as late as Mother's Day – but wait until after the first mowing. A second application should be around Labor Day to get the lawn growing again for the fall, and a third application in October (no later than October 15) will keep roots healthy through winter and result in early spring greenup. If you want to use less fertilizer, try only the first and third applications or just the first. Older, established lawns may need only one application, or perhaps fertilizer applications on less than an annual basis.
top of page

Types: How do you choose between products with the same nutrient content? The big choice is between fast and slow release of the nitrogen fraction. The percentage of the total nitrogen that is not water soluble and that which is water soluble usually is listed on the fertilizer bag. In the water soluble form the nitrogen is available quickly, and in the insoluble form it is available slowly. A good turf fertilizer contains some of each kind of nitrogen. The slow release portion provides nitrogen over a period of time but is not available to the plant during cool weather. The soluble fraction, or fast release, will provide nitrogen almost immediately after application and during cool weather. Something approaching 30 percent to 50 percent insoluble or slow release (time released) nitrogen is suggested.

Lime
Ground limestone may be applied at any time of year, though late summer to early fall is the best time. There is no waiting period necessary between liming and fertilizing. Most soils in Rhode Island are slightly acidic and can usually benefit from a general maintenance application of lime – usually 40 lbs. per 1000 square feet –  but a soil pH test tells you exactly how much you need. Unless your soil is really acidic, a lime application every few years should be adequate.

Watering
Unless watered regularly, a well-established lawn may naturally go into a dormant 'brown' period during hot summer months. This is not a problem: the lawn is not dead and will become green again in the fall when conditions are cooler and damper, unless the drought is prolonged. However, allowing the lawn to go dormant may mask insect and disease problems – dead areas may be evident when greening does occur.

 If you water during the summer, do so regularly using the following guidelines: (1) Water your lawn slowly and thoroughly, enough to wet to a depth of 4 to 6 inches. One inch of water (or rainfall) every week is sufficient. Light, frequent waterings are undesirable (except when establishing a lawn from seed) because they encourage shallow root systems. (2 When grass blades turn a dry, bluish green, the edges of the blades curl, or a 'foot print' is left after walking, it is past the time to water – water as soon as possible. (3) Watering is best done in early morning to reduce waste and also to reduce the chance of disease (foliage that is wet all night is more subject to disease).
top of page

Mowing
A good rule of thumb is to keep the lawn at a height of about 2 ½ to 3 inches. Also, mow frequently enough that you do not remove more than one third of the leaf blade at one time. During the summer, the lawn should be cut to no less than 3 inches. Fescues and shade grasses are grown a little longer than bluegrass. There is a direct relationship between grass length and rooting depth, so grass kept too short is less able to withstand drought and stress and will make the lawn more susceptible to weed and insect problems, as well.

It is not necessary to remove clippings from a lawn if it is mowed frequently. Do not let the lawn grow very high and then cut it back all at once; this can be a shock to the grass and can severely weaken it. This will also require the removal of the clippings so that they do not smother the lawn. If the lawn has become very long, shorten it gradually with a series of successively mowings.

Use a sharp mower; the cut should be clean with no shredding or tearing of the plants. Do not mow or work on a lawn when it is frozen or very muddy. These practices can damage a lawn.

Renovation
Lawns sometimes deteriorate over a period of years to the point where they cannot be nurtured back to an acceptable level of quality using standard cultural practices such as fertilizing, proper watering, etc. The lawn may be in poor condition because improper grasses were used initially or because they have become "out of balance." Overuse, neglect, extensive thatch accumulation, disease, insect and/or mechanical damage, or a heavy infestation of weeds are other reasons to renovate. Renovation consists of eliminating whatever factors cause poor quality followed by reseeding without completely tilling under the lawn. The process of renovating may be as basic as simply reseeding bare spots, or as involved as killing all vegetation using a nonselective herbicide followed by reseeding the entire lawn.
    
Timing: Renovation during late summer (August 15 - September 15) generally yields the best results because there is minimal weed competition as well as cooler temperatures and ample rainfall to provide a favorable environment for new seedlings. Late summer seeding must be accomplished early enough to allow the grass to become well established before the onset of cold weather in order to enhance winter survival. Renovation should be attempted during spring only if absolutely necessary. As late spring approaches, extensive weed competition coupled with summer drought and heat stress reduce the probability of success.
top of page

Procedure: The following procedure is designed for renovation of large areas of lawn or entire lawns. If only a few small spots require reseeding, Steps 2 and 3 may be eliminated.

1. Correct whatever factors caused the lawn to deteriorate to the point of needing renovation because renovation will only yield temporary improvement unless the original cause of poor quality is remedied. For example, recontour the lawn if necessary, improve drainage, eliminate excessive shade, etc.
   
   
2. Control all weeds. Most broadleaf weeds can be selectively eliminated by using a broadleaf weed killer. Some weeds and small infestations of bunch-type (non-spreading) weedy grasses can be removed by digging. Remove the weed, grass, and soil to a depth of about 2 to 3ches. Remove soil for a distance of about 2 to 3 inches outside of the clump to ensure the removal of all parts of the undesirable plant.

Perennial weeds that spread via underground stems (rhizomes) or aboveground runners (stolons) cannot be controlled by digging. Spreading perennial grasses, such as quackgrass and bentgrass, should be controlled using a broadleaf weed killer.

It may be advisable to permit the lawn to grow slightly higher than normal prior to weed control to allow the weeds to grow larger, thus producing more leaf area for better herbicide uptake. Wait at least 10 to 14 days following herbicide application before proceeding with renovation in order to allow for complete herbicide uptake and allow any chemical residues in the soil to dissipate. Always follow label recommendations when using herbicides for specific information concerning rate of application, weeds controlled, and waiting period before reseeding
top of page
.

3. Mow the entire area as low as possible (½ to ¾ inch) and remove all debris. If there is an appreciable accumulation of thatch (more than ½ inch), remove it using a dethatcher. A dethatcher is a power-driven machine similar to a lawn mower, but with a series of vertical blades or tines which rotate on a horizontal shaft to remove surface debris and thatch. Several passes over the area may be needed to achieve desired results. Remove all debris created by this operation.
   
4. Cultivate the soil in order to assure good seed-to-soil contact. This is an important step, since seed broadcast onto a lawn without proper cultivation will not survive. Cultivate to a depth of about ¼ inch. On small areas, a garden rake can be used to loosen soil to the proper depth.
5. Fertilize and lime (if necessary) at this time. Proper soil fertility and pH are essential for successful renovation. Base application rates of these materials on soil test results. If soil test recommendations are unavailable, approximately 2 lbs of phosphorus and potassium per 1000 sq. ft and approximately 1 lb of nitrogen per 1000 sq. ft should be worked into the soil to promote seedling growth. "Starter" fertilizers containing substantial phosphorous can be purchased for this purpose.
6. Seed of a species similar to that existing in the lawn should be used unless improper species selection was the original cause of poor quality. Apply seed uniformly over the area to be renovated. Use a seeding rate for a new lawn if a herbicide was used on the entire area, or one half the rate for a new lawn if 50 percent of the turf is still present. In order to insure uniform coverage, apply the seed in two directions at right angles to each other.
7. Rake lightly following seeding (a leaf rake works well), or drag with a steel mat or door mat to work the seed into the soil to a depth of about ¼ inch. The area should then be rolled to ensure good seed-to-soil contact. If the area being renovated is on a slope, apply a weed-free mulch to prevent erosion.
8. Water lightly and frequently, two to three times per day, to keep the seed bed damp during the period of germination and establishment. The duration of germination and establishment will vary among grass species, with perennial ryegrass being the fastest species to establish and Kentucky bluegrass the slowest. Continue to mow the lawn on a regular basis during renovation.
9. Apply a balanced fertilizer to provide ½ to 1 lb of nitrogen per 1000 sq. ft when seedlings are about 2 inches high. This will enhance growth and hasten recovery of the lawn to the desired quality.
   top of page

Growing Grass Under Shaded Conditions

The most obvious impact of shade is a reduction in the amount of light available to the grass. If a plant does not receive enough sunlight to manufacture sufficient "food" (carbohydrates), its vigor and growth will be reduced. In addition to reducing the total amount of light available, tree (or building) shade also severely limits the amount of useful light reaching the grass: the majority of light reaching shaded turf is likely to be light which has filtered through a tree canopy and is low in the wavelengths most valuable in photosynthesis and carbohydrate production.

Site Renovation
Aside from altering light reaching the grass, some trees produce surface roots that compete with grass for nutrients and water. This further inhibits the ability of the grass to grow and it becomes very difficult to maintain a lawn of desirable quality. Exclusion of rainfall by tree canopies can also dispose shaded grass to drought stress. Increased relative humidity and decreased air circulation in wooded areas favor development of lawn grass diseases, such as powdery mildew, as well as encouraging moss and algae problems.

To minimize shade problems for grass consider removing trees and shrubs that do not contribute meaningfully to the landscape design. Pruning tree limbs that grow at heights below eight to ten feet can often substantially improve the amount of morning and afternoon sunlight reaching the lawn. Selective thinning of the tree canopy itself will also allow more photosynthetically useful light to penetrate to the turf. Planting of shallow-rooted trees such as willow, maple, cottonwood, and sweetgum should be avoided, if possible, in order to reduce nutrient and water deficits due to root competition and to avoid future impediments to mowing.

Shade-Tolerant Grasses
When establishing a lawn under shaded conditions, species and cultivars possessing good shade tolerance should be chosen. The fine-leaved fescues (hard, sheep, and  Chewings fescue, and creeping red fescue) are, as a group, generally well-adapted to shaded conditions. Although widely used throughout the northeastern U.S., only a limited number of Kentucky bluegrass cultivars possess adequate shade tolerance to provide a quality turf under shade. Rough bluegrass is highly shade tolerant – there is no better grass for use under a shade tree – and prefers moist soils.
top of page

Lawn Management Under Trees

• Avoid excessive nitrogen fertilization. Apply fertilizer in shady areas in the fall just as leaves begin to drop. Rake and remove leaves before they accumulate. If fall fertilization was missed, fertilize in early spring, about a month before trees begin to leaf out.
• Keep grass long (2 ½ to 3 inches to allow maximum interception of reduced light. Avoid scalping turf.
• Irrigate only enough to avoid droughty soil conditions during summer months. Water infrequently and deeply; frequent irrigation can lead to increased humidity and disease. Irrigate in the early morning to allow maximum time for drying. Above all, do not overwater turf in shade. Dry conditions are always preferable to wet conditions for fescues growing in shade.
• Limit traffic and aerate compacted areas that receive heavy traffic.
• Avoid using herbicides if weed problems do not exist. Many weeds, especially crabgrass, will not grow in shade.
  

Selection of Grass

When selecting grasses to establish a lawn, consider species that will be best adapted to your environmental conditions, intended use, and the maintenance level at that particular site. Grasses vary in tolerance of soil moisture, pH, fertility and temperature ranges. They also vary in resistance to stresses caused by excessive wear, mowing, insects and diseases.

In the Northeast, many species of cool-season grasses (characterized by maximum growth in the spring and fall and semi-dormant during hot and/or dry periods of summer) can be used alone or in mixtures to produce a dense lawn. The principal species of cool-season grasses for lawns are: Kentucky bluegrass, perennial ryegrass, tall fescue and fine fescues (creeping red, Chewings, and hard). Creeping bentgrass, a cool-season grass used for very closely-mown, high-maintenance playing surfaces such as putting greens or croquet courts, is not an appropriate lawn grass.
top of page

Certain cultivars of perennial ryegrass, tall fescue, and fine fescues also contain fungal endophytes. A fungus living inside these grasses enhances the qualities of the turf but is not visible on the grass surface. Endophytic grasses have a high tolerance for environmental stresses and may perform well under low-maintenance regimes. They also have resistance to leaf-feeding insects such as billbugs, sod webworms, and chinch bugs. Fine fescues containing these endophytes also resist dollar spot, a disease associated with low fertility.

Kentucky Bluegrass
Kentucky bluegrass has fine to medium leaf texture and is dark green in color. It spreads via underground stems, allowing for good sod-forming abilities. (Sod is a monoculture of Kentucky bluegrass.) Tolerance is high for cold temperatures and wear, and moderate for heat and drought. The grass becomes semi-dormant under hot and dry conditions. It will recover quickly in cooler temperatures and with adequate moisture. Kentucky bluegrass is best grown in well-drained, sunny areas. It requires higher amounts of nitrogen fertilizer than some other cool-season grasses and may produce a significant amount of thatch if over-fertilized or over-watered. Kentucky bluegrass may be susceptible to such diseases as leaf spot, dollar spot, stripe smut, necrotic ring spot and summer patch. Some newer cultivars show some disease resistance.
top of page

Rough Bluegrass
Rough bluegrass is similar to Kentucky bluegrass in appearance, but it has a lighter green color and produces aboveground stems called stolons which allow it to spread and generate new tillers. This species is highly shade tolerant – there is no better grass for use under a shade tree – and prefers moist soils. When used in well-drained, open, sunny areas, it normally will decline during the hot, dry months of summer but may recover in cool, wet weather. Because of its light-green color, a tendency to form patches, and its lack of water tolerance, it is generally used only in shady lawns.

Perennial Ryegrass
Perennial ryegrass has a fine to medium leaf texture and tends to be dark green. It germinates rapidly and is quick to establish, making it suitable for overseeding. It is competitive with other grasses, however, and is used either alone or in combinations with Kentucky bluegrass or fine fescues. It is wear- and heat-tolerant, but will not withstand shade and drought well. It is susceptible to frost injury, although some cultivars recover from this damage better than others. Perennial ryegrass does best on well-drained soils with moderate fertility. There is little thatch accumulation. Perennial ryegrass is most susceptible to diseases such as brown patch, Pythium blight, dollar spot, red thread and rust. Several cultivars of perennial ryegrass contain beneficial fungal endophytes, which provide some insect resistance.

Tall Fescues
Many new, finer textured, darker green "turf-type" varieties now make tall fescue an option for lawns. Tall fescue is slow to establish, preferring temperatures above 70 degrees F for optimal germination. It has only a fair recovery potential, but it is both heat and drought tolerant. Tall fescue performs best in well-drained soils in open, sunny areas but can withstand moderate shade. Overall, it is more shade tolerant than Kentucky bluegrass and perennial ryegrass, but less so than the fine fescues. Thatch accumulation is mninmal. Tall fescue is highly susceptible to brown patch, red thread, and Pythium blight.

Fine Fescues (creeping red fescue, Chewings fescue, hard fescue)
These narrow-leaved, medium-green to dark green grasses can be used either alone or in combination with other grasses. Each species varies somewhat in terms of growth characteristics but all are ideal for low-maintenance situations. They are very tolerant of low pH and fertility, and of drought and shade. Fine fescues do not perform well under hot, humid conditions or with high levels of fertility. Fine fescues become semi-dormant in heat and drought, but recover quickly. These grasses have minimal production of thatch. They are susceptible to leaf spot, red thread and dollar spot. Endophyte-containing cultivars have resistance to dollar spot and some insect resistance.
top of page

Mixes and Blends
A grass seed mix is made up of two or more different species of grasses. A typical home lawn seed mix, for example, may be made up of varieties of Kentucky bluegrass, perennial ryegrass, and fescues, a mix that is generally fairly adaptable to differing site conditions (shade, full sun, dry, moist). Most lawns should be made up of a mixture of grasses appropriate for the particular site. A blend is made up of two or more cultivars or varieties of the same species of grass. For instance, a blend of perennial ryegrass might be made up of three or more varieties of perennial ryegrass. Blends are often used in highly-maintained lawns where extremely uniform appearance and performance are required, or for overseeding established lawns or play areas. For either blends or mixes, include at least three cultivars or varieties.

Endophyte-Enhanced Grass
Adapted from the University of Massachusetts Extension, 1999

The term "endophytic" refers to a situation where one organism lives inside another. In this case, a fungus and grass form a relationship that is mutually beneficial and enhances the reproductive success of each. These endophytes are transferred from plant to plant via seed. The fungus then grows into the sheath, stem, and leaf tissues of the developing grass seedling and maturing plant and finally enters the flowering stem and seed.

Endophyte-infected grasses tend to be comparatively vigorous, especially under conditions of minimal fertilization and irrigation. Infected plants produce greater numbers of tillers and roots, making them more drought-tolerant, more competitive with weed species, able to recover more rapidly from injury and generally more persistent in the field. The higher performance is particularly notable under stressful conditions such as high temperature, as well as nutrient and water deficiency. The result is a grass that is highly suitable for medium to low input situations.

Endophytic grasses have shown high resistance to foliar-feeding insects such as billbugs, chinch bugs, sod webworms, fall army-worms and argentine stem weevils. Biologically active alkaloids are found only in infected grasses. The insecticidal effects produced by these compounds deter insect infestations, resulting in a population decline. Alkaloid levels in the roots are low, however, and endophytes are thus not effective against root feeders such as white grubs.
top of page

The number of endophyte-infected, improved cultivars of tall fescue, perennial ryegrass, and fine fescues is increasing. A combination of these endophyte-infected varieties is often marketed as a low-maintenance mixture. Despite attempts to incorporate endophytic fungi into Kentucky bluegrass and bentgrasses, these high quality grasses are still endophyte-free. In order to maintain the viability of the endophyte, seeds must be stored at cool temperatures (approx. 40 degrees F) and under dry conditions. Even under excellent storage conditions, the percentage of viable endophytes in a seed lot will decline over time. In contrast, however, endophytes last indefinitely in plants; the endophytic content of a lawn typically increases over time. Endophytic grass seed is available at better garden centers and seed stores. It is only slightly more expensive than other seed and well worth the investment. Use only fresh seed to maximize endophyte content.

Usefull Websites

The Home Lawn: Controlling Insects (University of Minnesota Extension)
The Homeowner's Lawn Care Water Quality Almanac (Cornell University Cooperative Extension)
Penn State Turfgrass Management
Spring and Summer Lawn Management Considerations for Cool-Season Turfgrasses (Virginia Tech Cooperative Extension)
Turf Program, University of Massachusetts Extension

top of page