Installing A Sod Lawn
The installation of sod is a popular way to establish a new lawn. Most of the sod purchased is a blend of different Kentucky bluegrass varieties or a mixture of some of the other common turfgrass types used on Long Island (i.e., fine fescue, perennial ryegrass, tall fescue). When installed correctly on properly amended soil, in the appropriate sunlight conditions and where correct maintenance is provided, a sod lawn can be a valuable part of your landscape.
Unfortunately sod is often installed on top of soil which has had little or no preparation. Sometimes little consideration is given to the turfgrass species sunlight requirements. Another problem is the "advice" the owner of the new lawn receives in regard to the maintenance Kentucky bluegrass sod requires. Although Kentucky bluegrass requires a certain level of maintenance to perform at its best and to offer its best aesthetic qualities it does not require the wasteful practices we often see property owners providing (i.e., exceeding recommended fertilizer rates and frequency, frequent over watering, excessive use of pesticides when problems do not exist, etc.).
With a little planning, preparation and correct maintenance, Kentucky bluegrass sod (and other types) can be an asset to your property.
SITE SELECTION AND PREPARATION
Survey the site before selecting the grass type and/or varieties which will dominate the sod you purchase. Most of the Kentucky bluegrass varieties grow best in sites receiving full sunlight all day. There are a few varieties which will tolerate moderate amounts of shade. If the site is too shady you will need to consider another type of grass for best results.
If obnoxious perennial and/or annual weeds exist on the site it is best to consider controlling these (if possible) before the sod lawn is installed.
Correct Drainage Problems.
Drainage problems need to be addressed before installing sod. If excess water does not drain rapidly through the soil, the turfgrass will have a poor root system and will grow weak. In some instances you may need to consider installing a drainage system to move excess water from problem areas in your yard to areas where the water will not cause a problem.
Be sure to grade the soil away from fixed points on your yard (i.e. your house, the sidewalk, etc.). You should do this with gradual, gentle slopes so that water will be directed away from your home and off your property.
The need to acquire topsoil is not a necessity when installing a sod lawn. Often existing soil is suitable for sod or can be improved to make it suitable.
- The first thing to do is have your soil tested for soil pH and nutrient levels. The test results will direct you in how to improve your existing soil. The soil pH should be between 6.0 and 7.0 for best results. Limestone is used to increase the soil pH and should be mixed with the top 6 inches of soil before the soil is final graded. This is also the time to correct any nutrient deficiencies.
- If you do not test the soil you will have to rely on certain "rules of thumb" in regard to additions of limestone and fertilizer. Add 50 lbs. of dolomitic limestone per 1000 square feet. Starter fertilizers in 1-2-1 or 3-4-1 ratios (i.e. 10-20-10 or 18-24-6) should be added at the rate of 1 lb. of nitrogen per 1000 square feet. The limestone and fertilizer should be mixed with the top 6 inches of soil.
- Most soils benefit from additions of organic matter.
- To improve a sandy soil, work about 1-2 inches of organic matter into the top 4-6 inches of soil. Another method is to thoroughly mix 1 inch of heavier soil with the top 4 inches of sand. A better alternative is to add both organic matter and heavier soil rather than one or the other.
- If a heavy or "clay-like" soil needs improvement you should work organic matter into it. Do not add sand into a clay soil, since this will cause it to pack harder than before much like concrete.
- Organic matter sources vary. Consider using 4 large (6-cubic foot) bales of peat or 2 to 3 cubic yards of well-rotted manure or cultivated peat. Similar amounts of finished compost could also be considered. These volumes should be evenly spread across 1000 square feet and mixed with the top 4-6 inches of soil.
If you decide to bring in topsoil you should plan on adding at least 4-6 inches of good topsoil, even though it is expensive. You need to consider at least this amount since a 6-inch layer of loose soil settles to about 5 inches. Turfgrass roots will occupy approximately 5 or 6 inches of soil. If the topsoil layer is too thin the turf may actually be growing in the pre-existing soil.
If possible plan ahead when purchasing topsoil. In this case you will have adequate time to have the soil tested for pH, nutrients and physical analysis.
Soil grade changes have the potential to damage and kill existing trees on your property. If you are going to add topsoil over the roots of existing trees it is imperative that you take the appropriate steps necessary to prevent damaging and killing trees. A simple "well" constructed around the trunks of trees is not sufficient. Contact a qualified professional arborist (tree specialist) for information on the necessary procedures you will need to follow to insure that grade changes will not eventually kill the valuable trees on your property.
Sod should be installed on top of finely graded soil. After you have installed all drainage systems, added topsoil and/or soil amendments and have rough graded the area it is time to final grade.
- The soil should be raked to produce a smooth surface. This firms the soil and allows any remaining small humps and hollows to show in the soil. If any exist they should be corrected at this time.
- A mixture of soil granules and small clods of soil is preferred over a soil which has a very powdery surface.
- You may want to make a single trip with a light roller over the soil. This will help firm the soil and also helps show any small humps and hollows which may need correcting.
INSTALLING THE SOD
With proper irrigation sod can be installed almost anytime during the growing season when the ground is not frozen. It is desirable to plan ahead though and consider installing sod in the late summer - early fall. As with seeding this time of the year is usually very conducive to the environmental conditions needed for rapid establishment. Although it can be done if necessary, it may be wise to avoid installing sod during very hot, dry and humid conditions during the summer. The frequent watering needed to establish new sod during this time may encourage diseases such as Pythium blight, which can be devastating to a lawn.
Installing The Sod.
Make sure that the sod pieces are not dried out or wilted. Also be sure that the pieces are at least 1 inch thick. If the sod is not fresh cut and healthy do not accept it.
The soil should be flat and moderately moist.
- Do not leave the sod stacked in piles. If you cannot install it immediately lay the pieces out in a shady location. For best results the sod should be laid as soon after delivery as possible. Preferably no more than 36 hours after it is cut.
Lay the sod strips on the prepared soil tightly together, edge to edge, and with staggered joints like bricks in a wall.
- If needed, water the soil ahead of time very lightly. This improves the ability of the sod to survive and knit in faster.
Fill cracks with soil if necessary.
Immediately soak the newly laid sod thoroughly.
As soon as it is dry enough to walk on, lightly roll or tamp the sod to give a good contact with the soil beneath. This is necessary to remove any air pockets which will interfere with proper rooting.
Correct watering after installing the sod is critical to its survival. The idea is to keep the soil under the sod moist as well as the soil which comes with each sod piece. This does not mean constantly wet and soggy. Usually 1 inch of water every 2 to 3 days applied in the early part of the day will be sufficient to keep the soil moist.
Check on the moisture conditions from time to time by lifting the corners of the sod pieces. If the sod/soil seems excessively wet by the second day then delay watering until the third day.
- Measure 1 inch of water by placing several straight sided coffee cans in the sprinkler output pattern.
Water only as frequently as necessary to keep the soil/sod moist, not soggy and wet. It is most important that you do not over water and avoid saturating the sod/soil since this will prevent the sod from re-rooting and cause the roots to rot.
After the sod has knitted (rooted) to the soil (from 1-3 weeks), it is important to change the watering schedule. Watering should be done thoroughly to soak the root zone (top 4-5 inches of soil) but infrequently. Providing 1 inch of supplemental irrigation every 4-7 days (depending on soil, temperatures and rainfall) should be adequate for most lawns. There is no need for daily watering of a sod lawn.
Normally a newly installed sod lawn will probably require mowing 4 to 7 days after it is installed. Do not mow sod too short. A good length to consider is 2 inches. Never remove more than 1/3 of the leaf blade when mowing the lawn. It is not necessary to remove or pick up grass clippings after mowing if you mow the lawn as frequently as is necessary. Grass clippings do not cause thatch layers.
The lawn will probably require fertilizing approximately 4-6 weeks after it is installed. Apply a complete fertilizer with a ratio of 2-1-1 or 4-1-3 at the rate of 1 pound of nitrogen per 1000 square feet. Lightly water in the fertilizer after it is applied.
After this initial fertilizer application, a sod lawn installed on properly prepared soil should need fertilizing no more than 3 times per year. Use a fertilizer with a ratio of 2-1-1 or 4-1-3 or similar ratio fertilizer. Do not exceed 1 pound of nitrogen per 1000 square feet per application. Always use fertilizers containing adequate amounts of slow-release nitrogen. Fertilizer is usually applied in early September (Labor Day), late November (Thanksgiving) and in late May (Memorial Day).
Resource: Home Lawns, by A. Martin Petrovic and John F. Cornman, Information Bulletin 185, A Cornell Cooperative Extension Publication, 5/82.
Prepared by: Thomas Kowalsick, Extension Educator, Cornell Cooperative Extension - Suffolk County
1/99 Slight Revision