Reviewed March 2003
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Establishment of turfgrass brings beauty to any landscape. While preparing an area for turf, do not hurry the process. Mistakes made at that time will be evident later and will cost extra in time and labor. The success of a beautiful turf is dependent on many factors, including initial soil preparation.
General steps to turfgrass establishment
You may not need to follow all of the above steps to establish your lawn. For example, the soil need not be completely tilled where grading and soil amendments are not required and when soils are not excessively compacted.
Once soil has been tilled, considerable time and effort are required to prepare a firm, granular seedbed. Where surface grade and soil physical conditions are acceptable, lawns can be re-established with minimal effort by killing the existing undesirable vegetation and incorporating seed into the surface. (See lawn renovation section.)
Regardless of how the site is prepared, it is important that seed be incorporated into the top 1/4 inch of soil. On loose, bare soils, this can easily be done by lightly raking the seed into the surface. On hard compact soils or soils with existing vegetation and thatch, the seed should be mechanically incorporated into the soil by verticutting, slit-seeding, or intense coring. Scattering seed on the surface without incorporation is a waste of time and money.
Soil testing
A soil test is needed to determine the lime and fertilizer requirements
to ensure good turfgrass establishment and future growth. The test results provide
your soil pH value and if lime will be required. A soil pH between 6.0 and 6.8
is optimum for turfgrass growth. When pH is optimum, other nutrients such as
nitrogen, phosphorus and potassium are readily available from the soil for plant
uptake. Lime is used to raise soil pH, and sulphur is added to lower pH. Phosphorus
and potassium needs, if any, will also be indicated on the soil test report.
Phosphorus is especially important for root development and seedling establishment.
Phosphorus is most effective when incorporated into the top 4 to 6 inches of
the soil because it moves downward slowly.
Soil testing and sample bags may be obtained from your local MU Extension center for a nominal fee. Send soil for analysis two months before your planting date to allow sufficient time for you to receive fertilizer recommendations and purchase the appropriate materials.
Soil preparation
Proper attention to grading for surface drainage and conserving or
developing topsoil will lead to easier care of your lawn in the years to come.
Push aside existing topsoil when construction or excessive grade changes are
required. Topsoil will be evenly spread over the site once the rough grading
is completed.
When building a new home where a basement or foundation is dug, insist that the excavated subsoil is not combined with the existing topsoil. Trees, shrubs, groundcovers and lawns never develop to their full potential in poor quality subsoil. The initial investment in retaining on-site topsoil or amending poor quality soils will avoid the agonizing replacement of plants that could not tolerate the poor soil environment.
The area should be rough graded with gentle slopes to adequately drain or divert surface water without erosion. Slopes with a 1-foot drop in 50 feet should be adequate, but should not exceed a 1-foot drop in 15 feet. The finished grade should slope away from the foundation. On sites where topsoil is added over subsoil, be sure that the finished grade is at least 3 inches below the top of the foundation of basement homes. Surface runoff can cause basement flooding if water runs over the basement foundation. Remove all debris such as large stones, tree roots and discarded construction materials that will interfere with turfgrass root growth and water movement through the soil.
Liming and fertilizing
Apply the required amount of lime, phosphorus and potassium recommended
on the soil test report for establishing a lawn. Where a soil test is not available,
and if soils have required liming in the past but have not been limed for at
least two years, apply 25 pounds of finely ground limestone per 1,000 square
feet. Also apply 5 to 7 pounds of 0-46-0 phosphorus fertilizer per 1,000 square
feet. Phosphorus is not very mobile in the soil and should be incorporated in
the root zone (top 4 to 6 inches of soil) during this step. Nitrogen and potassium
are highly mobile in the soil and easily can be distributed by surface application.
Thoroughly till the lime and fertilizer materials into the surface 4 to 6 inches of soil. Do not exceed 3 pounds of 0-46-0 fertilizer per 1,000 square feet if nutrients are not to be incorporated into the top 4 to 6 inches of soil. These practices are aimed at building the basic soil fertility to an acceptable level.
Broadcast and work into the top inch of soil 5 pounds of 20-27-5 or 19-25-5 fertilizer or 10 pounds of a 10-24-18 fertilizer, or the equivalent, per 1,000 square feet. The fertilizer should be turf grade and contain 30 percent or more of the total nitrogen as water-insoluble or controlled-release nitrogen. Application at the recommended rate should provide adequate nutrition for the first three months of growth.
As an alternative starter fertilizer, apply 10 pounds of 10-10-10 or 12-12-12 farm-grade (soluble nitrogen) fertilizer or equivalent per 1,000 square feet (for example, 5 to 6 pounds of 20-20-20 fertilizer per 1,000 square feet). Using nitrogen fertilizers that contain only soluble nitrogen will necessitate additional nitrogen after six to eight weeks of growing weather.
Soil amendments
A soil test will indicate if organic matter is required. Organic matter,
such as peat moss or compost, can be added to clay soils to improve drainage
and aerification. The same organic matter can be added to sandy soils to help
hold water and nutrients in the soil. Fresh organic matter -- manure, straw
or fresh saw dust -- is not usually recommended because it can cause a temporary
nitrogen imbalance that will lead to slow growth and grass yellowing.
Reed-sedge peat and moss peat are also good sources of organic matter that tend to last longer in the soil than most other organic matter sources. Organic matter should be worked into the top 2 to 4 inches of soil before applying the starter fertilizer.
Final grading
Rake the area to the finish grade just before seeding. Light rolling
will indicate any low spots or other irregularities to the area. A proper final
surface will be firm enough to prevent ruts made by seeding equipment but will
be loose and crumbly so that seed easily can be raked into the top 1/4 inch of
soil. Once these steps have been properly followed, you are ready to install
a turf by seeding or sodding.
When to establish
Selecting the right time of the year to seed cool-season grasses is
the most important factor in successful lawn establishment. The best time to
seed cool-season grasses is between Aug. 25 and Oct. 1. Lawns seeded within
a week of Labor Day are more likely to fill in completely by winter and produce
a thicker appearance the following spring than lawns seeded in October.
Seeding in late summer is preferred because temperatures are still warm enough to promote rapid germination when provided with rain or irrigation. The cooler temperatures and shorter days of the approaching fall are ideal for further growth and development of young seedling grasses.
Establishing cool-season grasses from seed in the spring can be extremely difficult. In some cases, complete failure should be expected. Rainfall or watering required to germinate turfgrass seeds during spring establishment will also promote excessive weed growth, especially crabgrass. If you are lucky enough to beat the crabgrass, expect to continue the battle with frequent summer irrigations to prevent moisture stress. Even if moisture is adequate, summer temperatures may severely thin or completely kill seedling turf. The constant summer watering required by seedling turf will also increase the chance of Pythium damping off and brown patch. Both of these fungal diseases are encouraged by the same conditions that promote seedling growth -- wet soils, frequent watering and summer nitrogen.
Sod of Kentucky bluegrass or tall fescue can be installed during most of the year except in mid-winter when the ground is frozen. When extreme heat and drought conditions exist in summer, sod should be cut and laid during a 12- to 24-hour period. If done under drought conditions, the turf must be kept moist and cool. The soil should be watered enough to cool it before installation. It should be thoroughly watered again immediately after the sod is laid.
Seed vs. sod
A quality lawn containing the recommended mixtures of specific grass
varieties and species can be established with either seed or sod. When seeding,
however, there are many more species and varieties from which to select. Most
sod grown in Missouri is straight Kentucky bluegrass or a mixture of mostly tall
fescue combined with a small amount of Kentucky bluegrass. Some tall fescue sod
is also available on plastic netting.
Initially, seed is less expensive than sod. However, successful establishment is more risky with seed than with sod, and if reseeding of certain areas or even an entire lawn is necessary, the overall expense may be less with sod. Also, the area is exposed to erosion because of the time required for seed to germinate and become well rooted in the soil. Sodding practically eliminates such problems, a consideration that may be especially important on steep hills or banks. Sod also reduces the chance of pesticide and nutrient contamination from surface runoff.
Sodding provides an immediately pleasing turf that is quickly functional, and it will compete with viable weed seed already present in the soil. Seeding usually requires weed control during the first year of establishment.
Seed should be used to establish lawns only in early fall or early spring, whereas sod offers less time limitation in that it may be established in nearly any season. Sodding of cool-season grasses in the spring is preferred to seeding.
Seeding
Before seeding, be sure that the soil has been prepared properly and
is smooth and level.
Seed small areas by hand. A fertilizer spreader can be used in larger areas. When seeding by hand, try to apply five to 10 seeds per square inch. Heavier seedings will cause weak, spindly seedlings and spotty establishment. Calibrate spreaders to supply half the amount of seed in one pass over the area. Divide the amount of seed to be sown into two groups. Spread the first group of seed. Then spread the second group at a right angle to the first group.
Rake the seed to cover it with 1/8 to 1/4 inch of soil. Roll lightly to make good contact between seed and soil. Use a light layer of straw as mulch -- one to one and one half bales per 1,000 square feet. This helps hasten germination, keeps soil moist and protects young seedlings. The soil should remain moist from the surface to just below the active root zone.
At first, this moist zone will be shallow and require light, frequent irrigation. Use a fine spray to sprinkle seeds one to four times per day until young seedlings are established. As the grass develops, irrigate deeper and less frequently. Always avoid puddles and runoff.
Sodding
Sodding is the installation of commercially grown turf. Sod has a carpetlike
appearance consisting of green shoots attached to roots and soil. It usually
comes in 3-foot sections, 18 inches wide, with less than 1/2 inch of soil attached.
Sodding has the advantage of almost immediate establishment, but its disadvantages are initial cost and the high amount of labor involved.
Choose high-quality sod that is actively growing. Sod is perishable and should not remain on the pallet or stack for more than a few hours. The presence of mildew and distinct yellowing of the leaves is usually good evidence of reduced turf vigor from being stacked too long.
To lay the sod, start with a straight edge such as a driveway or sidewalk. Unroll sod pieces tightly against each other, but don't overlap. Lay the pieces in a staggered, bricklike pattern. Using a sharp knife, cut pieces to fit curves or small areas. After the sod has been laid, roll it to ensure good contact with the soil. Be sure to water thoroughly, and water every day during dry, warm weather. Avoid soggy situations.
Newly seeded or sodded lawns require special irrigation. A newly seeded lawn requires daily watering and may need as many as four light waterings in a single day if conditions are dry and windy. Keep the seedbed moist, but not saturated, to a depth of 1 to 2 inches until germination occurs (green cast to lawn and seedlings 1/4 to 1/2 inch tall). At this stage it is crucial that seedlings not be stressed to the point of wilt.
Continue to water one to four times a day with light applications, approximately 1/8 to 1/4 inch of water per day. Straw applied at the time of seeding helps to shade the soil and to prevent rapid drying of the soil surface. It will also reduce soil erosion and seedling damage from the force of large sprinkler drops.
Watering with a light mist is best for establishing new lawns. As seedlings reach 2 inches, gradually reduce the frequency of watering and water more deeply. Begin mowing once a week when the seedlings reach a height of 3 inches. After the new lawn has been mowed two or three times, water deeply and infrequently.
Newly sodded lawns may require watering one or two times a day. Begin irrigation immediately after laying sod. Plan your sodding operation so that a section of laid sod can immediately be watered while other areas are being sodded. Sod should be watered so that the sod strip is wet as well as the top 1 inch of soil below the sod.
The first irrigation requires about 1 inch of water to achieve complete wetting of the sod. After watering, lift up pieces of sod at several locations to determine if it has been adequately irrigated. Continue watering one to two times a day or as needed with light irrigations to prevent wilting and to ensure a moist soil just below the sod layer. As sod becomes established and roots penetrate and grow in the soil, gradually reduce the frequency of watering but wet the soil deeper. After sod has been mowed two or three times water deeply and infrequently.
During hot, windy conditions, establishing sod may require several light mistings per day to prevent wilt and potentially high lethal temperatures. In this case, mist the sod lightly just to wet the leaf surface and not to supply water to the soil. Misting cools the grass plant as water is evaporated from the leaves.
Do not over-irrigate the soil because that will inhibit sod roots from growing into the soil. In situations where daily watering is not possible, thoroughly water the sod and soil to a depth of 6 inches. This will delay the rooting time of sod but will reduce the chance of rapid drying and severe loss of grass.
Spring seeded cool-season grasses
Even though spring seeding of cool-season grasses is not as successful
as fall seeding, spring and early summer seeding may be unavoidable. Some tips
may help your attempt to establish cool-season grasses.
| Higher -- spring seeding rate | Normal -- fall seeding rate | |
|---|---|---|
| Kentucky bluegrass | 3 pounds per 1,000 square feet | 2 pounds per 1,000 square feet |
| Perennial ryegrass | 10 pounds per 1,000 square feet | 7 pounds per 1,000 square feet |
| Tall fescue | 10 pounds per 1,000 square feet | 7 pounds per 1,000 square feet |
Fall seeded cool-season grasses
Fall seedings are much more successful than spring seedings because
crabgrass and summer stress are not a problem. However, winter annual broadleaved
weeds such as henbit, chickweed and speedwell may require control. These weeds
germinate September through November, grow during the winter and result in a
dense mat of weeds by early spring.
If weeds dominate the new lawn in the fall, use a postemergence herbicide after the lawn has been mowed at least three times, usually about 45 days after grass germination. Apply broadleaf herbicides on a warm sunny day in the fall when no frost is expected. If needed, winter annual broadleaved weeds can also be killed in late March and April. Even though these weeds naturally die in May, without herbicide application, they should be controlled in early spring if they are overly competitive.
If annual broadleaved weeds are left uncontrolled, turf will appear thin and weakened through the summer in areas where weeds have naturally died.
Lawns may occasionally thin out and become weedy as the result of poor management, pests or severe summer stress. Lawns that do not need regrading or soil tilling may be renovated by simply controlling weeds, planting seed and fertilizing. Also, determine the cause of lawn decline so that you can adjust your lawn care program.
Establishment practices mentioned above for time of seeding, weed control, fertility and watering also apply to renovation.
General steps to renovate turfgrass
Assess situation
First, assess your lawn situation for desirability and appropriateness
of the grass, presence of weeds and bare spots. Kill existing vegetation (grasses
and weeds) if any one of the following apply:
Lawns that have more than 50 percent desirable grass, but still appear thin and weak with several broadleaved weeds, may need only control of broadleaved weeds with broadleaf herbicides. After weed competition is reduced, lawns may regain their original density.
Bare patches less than 4 inches in diameter likely will fill in on their own with proper fertility and no additional seeding. Larger areas that remain too thin a month after broadleaf herbicide treatment may be overseeded. Shaded areas of lawns with thin turf and exposed soil often appear to need additional seeding. Renovate these areas but do not kill existing turf that has thus far survived the difficult growing conditions of shade.
Prepare surface for seeding
One of the most important steps in renovation is placing the seed in
contact with soil. This sounds simple, but most lawns have thatch - an intermingled
layer of both dead and living plants - over the soil surface. This brown, decomposing
layer may be up to 1-1/2 inches thick. Lawns with more than 1/2 inch of thatch should
be dethatched.
Seed placed on or in the thatch layer may germinate, but the eventual stand of grass that develops will be poor. To ensure good seed-to-soil contact, use power equipment to prepare the surface for seeding. Power rakes, verticutters, slit seeders and core aerators are effective machines for properly preparing the surface for seeding.
Dethatching equipment is sometimes available from local rental stores. Local lawn care and landscape companies also provide dethatching and renovation service. Two to four passes over the lawn may be necessary depending on the soil hardness and thatch thickness. Raking of excess debris will be necessary as well.
Power rake
Power rakes are lawn mower-like machines that have spring tines instead
of blades. The
power-driven spring tines rotate in a vertical position
and pull the thatch to the surface.
Spring tines that attach to the lawn mower blade do not adequately prepare the surface for seeding. A half inch of thatch can be removed with a severe power raking, but be prepared to handle several bags of loosened thatch. Power rakes that can be adjusted so that the soil surface is slightly scratched will ensure good seed-to-soil contact but may not loosen hard soils.
Vertical mower
Vertical mowers are similar to power rakes except that they have fixed
or flail-type blades that cut groves through the thatch and into the soil. Fixed-blade
vertical mowers, sometimes called slicers, are better at cutting into the soil.
Heavy-duty, walk-behind vertical mowers are superior to power rakes for preparing a seedbed. They cut deeper into the soil, 1/2 to 3/4 inch, redistribute some soil onto the surface, and provide some soil loosening that helps seedling establishment.
Power rakes and vertical mowers can accumulate a large amount of grass debris on the surface that should be removed so that the seed can contact the soil. After sufficient disruption of the surface, lightly rake the dead debris off the surface, leaving the loosened soil behind. After raking, a final pass with the equipment will produce closely spaced groves that are excellent channels for catching broadcast seed.
Slit seeder
Slit seeders are smaller versions of agricultural grain drills, but
with closer spacings between discs. The discs slice open the ground just ahead
of a small tube that drops the seed into the open furrow. A packing wheel follows
the seed tube and closes the sliced ground.
Some slit seeders also have a vertical mowing attachment in front of the discs that loosens and redistributes soil on the surface. A slit seeder sows grasses in distinct rows 2 to 6 inches apart depending on the space between the drill discs. It is important to repeat the seeding process at different angles. This usually can be accomplished with two to four passes across the lawn making a checkerboard pattern.
Core aerifier
Coring machines have a series of hollow tines that cut several cylindrical
holes in the ground 2 to 3 inches deep and 1/2 inch in diameter. Some machines
will not penetrate hard and dry compacted soils.
Coring machines are primarily used to provide a channel through which air, fertilizer and water can enter the soil. This channel cut through the thatch and into the soil helps to reduce soil compaction, increase root growth and redistribute soil on the upper surface of the thatch. The soil should be sufficiently moist so that the coring machine can penetrate. If a screwdriver can be pushed by hand 3 inches into the ground, the soil is about right. Soils that are too wet will clog the hollow tines and prevent core removal.
The soil cores should be left on the surface to create a more favorable environment for breakdown of the thatch layer by naturally occurring soil microbes. When the soil cores have dried, they can be chopped and dispersed over the surface with a mower, verticutter or power rake. If coring is to be the primary means of preparing a seedbed, the area should be cored to produce at least one hole every 2 inches. Seed and fertilize while the core holes are open.
Core aerifiers are of many different sizes and shapes. As with all equipment, check to see that it will fit through the gates on property gates before renting or contracting a service.
G6700, reviewed March 2003