Reviewed March 2003
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Established lawns may be maintained at different levels of perfection according to individual situations and desires, but good lawns seldom "just happen." This summary outlines major steps required to maintain a year-round high-quality lawn.
Note
This publication refers primarily to cool-season grasses such as Kentucky
bluegrass, perennial ryegrass, tall fescue and fine fescue.
Steps in boldface type indicate a minimum program where time, money or interest dictate a usable lawn with least effort. Other selected steps of the schedule may be adopted occasionally or in alternate years to upgrade the program.
Timing is approximate for central Missouri; it may vary two weeks or more from one area to another in the state or from year to year.
The key to good maintenance is doing those things that best counterbalance unfavorable conditions in the lawn environment. Lawns on soils of inferior physical quality or low fertility require more attention to attain equal success than those on deep, friable loam-type soils.
The steps below should provide satisfactory lawns if they are followed properly.
Variation in soils, lawn standards and grass require different approaches when fertilizing a lawn. The ideal program provides for uniform moderate growth throughout the season. Such growth can be provided through fertilization programs using organic forms of nitrogen.
Problems arise when rates and forms of fertilizer cause irregular "spurts of growth" especially in spring and summer. When turf is not fertilized enough, it has little competitive ability against weeds or disease.
Nitrogen recommendations and materials tend to overemphasize the dark green color and fast growth response. In too many cases this has been detrimental to balanced plant growth and health. For example, much emphasis has been given to early spring as the best time to fertilize bluegrass. If a lawn is stunted and has a pale to yellowish-green appearance, a very moderate feeding at this time would be advisable.
On the other hand, fertilizing a lawn that already had moderate vigor at the time most of us get "spring gardening fever" will stimulate excessive succulent growth. The grass becomes more susceptible to fungi, which will take their toll a few weeks later during summer stress. Further, excessive leaf growth usually occurs at the expense of new root growth; this places the plant at a further disadvantage for summer.
Table 1
Fertilizer application schedule
| Turf type | Nitrogen, apply at recommended rates* | May | September | October | November |
|---|---|---|---|---|---|
| Common type Kentucky bluegrasses | 2 to 3 pounds per year | X | X | X | |
| Higher quality bluegrasses | 4 to 5 pounds per year | X | X | X | X |
| Red fescues | 2 pounds per year | X | X | X | |
| Bluegrass and red fescue | 2 to 3 pounds per year | X | X | X | |
| Tall fescue or ryegrass | 3 to 4 pounds per year | X | X | X |
When to fertilize
All lawns should be fertilized at least once a year. Additional fertilization
will depend on the desired level of turf appearance, turfgrass species, soil
type and fertilizer carrier. If only one fertilization per year is desired, September
is an excellent target date to feed your lawn.
As indicated in Table 1, other fertilizer applications may be desirable and even necessary. When a second application is desired, do so about mid-October. Moderate rates in October or November, after days are cool enough to discourage vigorous leaf growth (50 degrees Fahrenheit), will help prolong green color into the winter and at the same time encourage development of a stronger root system for next spring’s growth.
If a spring fertilizer application is made, apply it in March or April. Two or three fertilizer applications in the fall may eliminate the need for a spring application.
When higher fertilization rates are followed, give greater attention to thatch and disease control measures, as well as to watering.
Nitrogen fertilizer
These materials are of two basic groups: soluble and slow
release . Soluble types are available quickly to plants even at low
temperatures, stimulate rapid growth and are depleted quickly (3 to 4 weeks).
Steady, uniform growth requires frequent, light applications.
Slow-release types of several different forms release nutrients to plants over longer periods of time (6 to 8 weeks) and very slowly at low temperatures.
Lawn specialty fertilizers often contain 24 to 50 percent of the total nitrogen in this form and the remainder in quickly soluble forms. This combination gives immediate response in cold weather while the remainder is available over a longer period.
When 35 to 50 percent or more of the nitrogen is a slow-release type, rates may be increased at least 50 percent, especially for high-quality management. With these types, frequency of application may sometimes be reduced.
A precaution should be observed: Nitrogen sources from urea (quickly soluble) should not be confused with urea-formaldehyde, UF, (slowly available).
Rates and frequency
Recommendations are usually based on amounts required to supply a given
amount of nitrogen per 1,000 square feet of lawn. Most lawn fertilizers are "complete" in
that they contain nitrogen (N), phosphorus (P) and potassium (K), and therefore
the amount of phosphorus and potassium applied is determined by the ratio of
these two elements to nitrogen.
Two fertilizers with label analyses of 20-5-10 and 12-12-12 would contain 20 and 12 percent N, 5 and 12 percent P and 10 and 12 percent K, respectively. For the first fertilizer, the N:P:K ratio would be 4:1:2, and the second would be 1:1:1.
The amount of fertilizer required to apply one pound nitrogen to 1,000 square feet can be calculated by dividing 100 by percent of nitrogen in the fertilizer (100 4 20 = 5 pounds fertilizer per 1,000). The same method would apply for phosphorus, potassium or any other nutrient percent.
Suggested annual fertilization schedule
For routine maintenance where soil test or experience indicates no major
deficiencies, use a lawn fertilizer with an approximate ratio of 3:1:1, or 4:1:1,
or 4:1:2 at recommended rates according to the schedule in Table 1.
Where soil test indicates low phosphorus or potassium levels or where basic fertility levels are not known, use fertilizers with a ratio that more closely approximates 1:1:1, or 2:1:1, or 3:1:2. If lawn application rates are not given on the container, amounts to apply can be calculated as in the example above.
Lime
Do not routinely apply lime to established lawns unless a soil test
indicates a need. Excess can be as harmful as deficiency. Established lawn soils
seldom need to be limed unless a soil test indicates a moderately to severely
acid soil of pH 5.8 or lower.
Where such need is indicated, apply finely ground or specially pelletized agricultural limestone at rates up to 50 pounds per 1,000 square feet. If more is required, make separate applications approximately six months apart. Limestone can be applied almost any time, but fall or early winter is the best time.
Table 2
Recommended seasonal mowing heights* for cool-season grasses in Missouri
| Turfgrass | Spring | Summer | Fall |
|---|---|---|---|
| Tall fescue | 2 to 3.5 inches | 3 to 4 inches | 2.5 to 3.5 inches |
| Kentucky bluegrass | 1.5 to 2.5 inches | 2 to 3.5 inches | 1.5 to 2.5 inches |
| Perennial ryegrass | 1.5 to 2.5 inches | 2.5 to 3.5 inches | 1.5 to 2 inches |
| Creeping red fescue | 1 to 2 inches | 2 to 3 inches | 1 to 2 inches |
| Chewings fescue | 1 to 2 inches | 2 to 3 inches | 1 to 2 inches |
| Hard fescue | 1.5 to 2.5 inches | 2 to 3 inches | 1.5 to 2.5inches |
| Sheep fescue | 1.5 to 2.5 inches | 2 to 3 inches | 1.5 to 2.5 inches |
Mowing height and frequency directly affect the performance of a lawn. The shorter turf is cut, the more frequently it should be mowed. The common practice of mowing a lawn short, under the assumption it will require less frequent cutting, is responsible for much lawn deterioration.
If cut too closely, there is not enough leaf surface to manufacture necessary foods for sustenance and root growth. For this reason, a standard guide is to never remove more than one-third of the green leaf area with a single mowing. If a mowing is missed, cut only half the way back to the intended height, then re-mow in a couple of days to the regular level. Recommended mowing heights are presented in Table 2.
Clippings need not always be removed. If mowed frequently so that they are short enough to filter down to the soil surface, they decay and recycle nutrients back to the soil. Remove clippings when they remain on the surface or when excessive thatch is already causing a problem.
Bluegrasses, fescues and other cool-season grasses naturally protect themselves by going into a semi dormant stage during periods of high temperature or drought. They cease growth and turn brown, but bounce back quickly with sufficient water and cooler temperatures (usually September).
Except in cases of extreme prolonged drought, tall fescue and Kentucky bluegrass do not need water to stay alive during the summer, however their appearance suffers. During dormancy, drought-tolerant weeds such as crabgrass, plantain, thistles and dandelion dominate lawns.
Because of its deep extensive root system, tall fescue remains green longer into the summer than other nonirrigated cool-season grasses.
Kentucky bluegrass has many underground stems, called rhizomes. Each rhizome can produce several new bluegrass shoots that result in turf thickening when water becomes available following summer dormancy, usually in September.
Perennial ryegrass and fescue, other than tall fescue, should not be grown as monocultures (only one grass species) without irrigation in Missouri because of their tendency to bunch during severe moisture stress.
The principal purpose of summer watering is to maintain an attractive green surface when it may be appreciated the most. Watering will not substitute for poor fertility or improper mowing, and can encourage crabgrass and other weed problems. Extra growth stimulated by watering increases fertility requirements, thatch accumulation and other problems.
If, in the desire for a summer green lawn, you cannot give attention to related management, let the turf follow its natural tendencies to go dormant during summer. (Plants are brown in appearance from lack of water, but not necessarily dead). Homeowners who have a lawn care service should not allow their lawn to enter drought dormancy.
Rules for watering
On clay- or silt-type soils, or any turf receiving constant traffic, soil sealing and compacting can seriously impair turf growth. Grass roots are injured because air, water and fertilizers cannot reach them in sufficient quantities. Mechanical aeration to break through this barrier is essential for continued turf health. Fertilizer applications following aerification most efficiently provide nutrients to the turf roots.
Aeration is best done by power equipment that pulls out small cores of soil, or by cutting vertical grooves to provide openings every 3 to 4 inches. Power equipment is usually available at rental stores. Lawn care companies may also provide this service to their customer.
For small areas, suitable hand equipment is available, but using it is hard work. Even an ordinary spading fork plunged into the soil at 3-inch intervals when the soil is lightly moist -- not wet -- is far better than nothing at all.
Aeration should be done at least once a year where compaction is a problem. Early fall is the best time for bluegrass lawns, but aeration will be highly beneficial anytime the grass is actively growing, except possibly during midsummer heat.
Thatch is a layer of undecayed plant parts accumulating at the turf base. It forms a barrier to water and air movement in the same manner as compaction.
Thatch is primarily a problem of intensely fertilized and watered lawns. Even though clippings are removed regularly, thatch still can form because old plants and basal leaves are more resistant to decay than are the clippings.
Thatch removal should be initiated whenever accumulation exceeds 1/2 inch. Early fall is the preferred time for dethatching lawns.
Topdressing is the periodic addition of a thin layer (1/4 to 1/2 inch) of soil to the surface of growing turf. Mixing soil with accumulating debris hastens thatch decay. Shallow depressions in a turf can be gradually leveled by this practice as well.
The texture of the topdressing material should be similar to or coarser than the soil on which the turf already exists. When topdressing with soil to reduce thatch, the addition of compost or peat moss is not required since the thatch layer is already high in organic matter.
Topdressing may be done immediately after coring, dethatching or slicing. Never bury the existing turf with too much topdressing soil. After topdressing, at least three-fourths of the grass plant should be exposed to sunlight. Never topdress during the heat of the summer.
Rolling is not desirable for smooth, uneven lawns. Surface compaction is common in many lawns without adding to the problem by heavy rolling. Rolling moist soil causes maximum compaction -- a fine way to build roadways but not soils for turf.
When late winter freezing and thawing have resulted in "heaving" young plants out of the ground, or if mole activity is serious, rolling may be required and is acceptable. In such cases, roll soon after spring thaw when the soil surface is relatively dry, and use as light a roller as possible. Don't roll more than is absolutely necessary.
The best weed control is a healthy, dense, competitive turf. Correct cultural practices to achieve this will keep out most weeds.
Chemical weed killers are useful, but should not be relied upon entirely to cure lawn weed problems. Suggestions for timing herbicide applications for several common weed problems are indicated in the calendar of this guide.
Relative merits of using fertilizer-herbicide (weed and feed) or fertilizer-insecticide combinations should be considered carefully before they are used indiscriminately. In many cases, at least one of the ingredients may not be needed or will be used at an inopportune time.
If your lawn is less than acceptable but contains at least 40 percent desirable grasses, you may be able to replant without preparing a completely new seedbed. Start in August with steps similar to the following:
Prevention is the best approach to disease problems in home lawns. Often by the time the disease is diagnosed, the damage has been done.
Controlling thatch, avoiding frequent sprinklings and fertilizing properly for healthy but not succulent grasses are simple lawn-grooming practices that aid disease prevention.
Two major insect pests are white grubs and sod webworm. Treating lawns every year with insecticides as prevention is neither necessary nor advised.
Routine inspections of the lawn for white grubs and sod webworms is advised. Treat only after the insects have been properly identified, and only when they are in sufficient numbers to cause a noticeable loss of turf.
G6705, reviewed March 2003