How to Lay Sod
Want a fantastic lawn? Sod it. Here's what you need to know to get the job done right
Slowing down and watching the grass grow sounds good. In theory. But the reality is that if your lawn needs renewing, you'll be looking at a big patch of dirt for weeks. And why wait, when summer can begin right now — with a lush green carpet underfoot?
When it comes to getting a thick, healthy lawn, nothing beats sod grass rolls for instant gratification. Sure, it costs a bit more: about $400 to cover a 1,000-square-foot backyard (double that installed). But if you follow our tips for laying sod, in a couple of weeks you’ll have a dense, well-established lawn that's naturally resistant to weeds, diseases, and pest infestations.
"You're basically buying time," says This Old House landscape contractor Roger Cook. "You're paying for turf that someone else has coddled for 14 to 18 months."
You're also buying convenience. Sod can be installed spring through fall (and even in winter in mild climates). In areas of the country that favor cool-season grasses, like the Northeast, it avoids the problem of sprouting a nice crop of weeds when seeding a lawn in spring. And in southern states, which favor warm-season grasses like Bermudagrass, zoysiagrass, and centipedegrass, sod is the best way to cover the yard at any time of year, since these turf types cannot be grown from seed.
"Sometimes sod gets a bad rap, but that's usually because of mistakes people make while laying it," says Roger. "Put down on properly prepared soil, it will thrive." Turf likes a well-aerated base that's slightly acidic (with a pH between 6 and 7.5) and nutrient-rich. And the only way to know what kind of soil you've got is to test it. For about $15, your local extension service will send a soil sample to a lab for analysis; results will come back within a week or two and indicate precisely what amendments you should add and in what quantity.
Then it's time to buy your sod. Depending on where you live, you can order it from a garden center or directly from a sod farm. It will generally be a mix of two or three turf grasses, chosen for optimal color, texture, and heartiness (be sure to tell your supplier if your yard's in partial or full shade). Ideally, sod should be delivered within 24 hours of being cut and be laid the same day. Measure your yard carefully so you can order the right amount, with some overage (about 5 percent) to account for cutting around curves.
Count on one weekend to prepare the soil for sod and another to lay the turf. If your yard is covered with patchy grass, you'll need to remove it first. This is best done with a sod cutter (available from your local rental yard for about $70 per day), which slices it off below the roots. While you're at it, you'll want to rent a rototiller (about $55 per day). You'll also need a sod-cutting knife with a 2-inch blade, a spreader, an iron rake, compost, and other soil amendments, including fertilizer and lime, depending on what your soil analysis dictates. Two people should be able to cover 1,000 square feet in a day; get extra hands if you plan to lay more than that.
Read on for our step-by-step instructions on how to prepare soil for sod and correctly lay out a beautiful carpet of green.
1. Prepare soil
Loosen the top 6 to 8 inches of soil with a rototiller. Spread 2 inches of finished compost (this may be available for free if your town has a municipal compost center). Add 2 to 3 inches of sand to claylike soil to improve drainage. Till in amendments. Then, based on the results from your soil test, use a spreader to lay down the appropriate starter fertilizer, and then lime if needed.
2. Level the surface
Use an iron rake to knock down any high spots and fill in low spots so the soil is level and 1 inch below the grade of any paved surface, such as a walkway or driveway. Water lightly to dampen the soil.
3. Lay the first row
Find the longest straight edge in your yard—here, it was the fence line. Unroll the first roll of sod along it. Keep off the sod while you are installing it, and rake out any footprints as you go. Smooth out loose areas or wrinkles, patting down the sod so it's flat against the soil underneath it, with no air pockets.
4. Lay subsequent rows
After laying the first row, use the knife to cut off half of the next piece so you can stagger the short seams, as you would in laying bricks. Again, make sure to butt sections of turf snugly against each other without overlapping them. Not only will seams be less noticeable this way but the edges will be less likely to dry out and die back. Use the knife to cut out holes for in-ground sprinkler heads as needed, and to trim pieces along planting beds and paved areas.
5. Water, water, water
Water the installed lawn thoroughly, which also helps settle the soil. Try to keep foot traffic off the sod for a week. Water every day, preferably in the morning: During the heat of the day, you lose a lot of water to evaporation. And if you water at night, the sod goes to bed wet, which can encourage fungal disease. After the first week, cut back watering to every other day, tapering off to just twice a week by the third week. Then like any lawn, give it an inch of water a week, more during hot summer months.
6. Mow the lawn
When the grass reaches 3 inches high, it's time to mow it down to 2 inches. Because your new lawn is still fragile, use a walk-behind mower (rather than the heavier ride-on type) for the first trim, and be sure to bag the clippings. Though you'll probably want to grow it higher in the summer months — to encourage a deep root system and to shade out weeds—always aim to cut off one-third of the grass's length anytime you mow, and be sure to use a sharp blade.
7. Fertilize once more
Allow your lawn about three to four weeks' growth, then feed it again with a starter fertilizer to make up for nutrients that washed away during the heavy watering schedule.
Secrets From Sod Farmers
These guys have made it their business to figure out the best way to grow lawn grasses. Here's some advice from the pros for DIY sod installation.
- Because sod is perishable and dries out quickly, many farmers cut their turf in the middle of the night so that it can be delivered and installed the same day. To keep it moist, consider watering the sod after you lay the first large area and move the sprinkler around the lawn as you complete each subsequent section.
- Even sod farmers can't tell how moist soil is by looking at a lawn. Use a soil probe (many types are available at home and garden centers) to check moisture levels. After a thorough watering, soil should be damp 3 to 4 inches below the surface.
- Strong turf needs plenty of sun; shade-grown grass is weaker and more susceptible to disease since it stays covered with dew longer. Water shady spots less often and reduce fertilizer by 25 percent.
Throwing Sod a Curve
Neat green rectangles of sod fit tightly against each other when laid in straight lines, but they won't conform to a curve, such as around the edge of a flower bed. Some people cut the sod lengthwise into strips that can be bent around a curve, but This Old House landscape contractor Roger Cook says smaller pieces like that are more likely to dry out and die than ones that remain full-width.
Instead, Roger makes his sod curve the way a tailor might, by cutting a dart or two in a full-sized piece. With the sod laid next to the curve, he grabs a couple of spots along one edge and pinces them together to make the sod follow the contours of the bed(1). This creates a triangular upward fold that he slices down its crease with a razor knife(2). One side of the cut goes down against the ground; he lays the other flap on top of it(3). Using the cut edge of this flap as a guide, he saws the knife through the sod and removes the triangular piece underneath(4). Now, the flaps meet and — voila — the cut disappears.
Before you spend a lot of money to lay down sod, spend a little bit to have your soil tested. Then you'll be sure you're providing the best environment for your new lawn to thrive.
A do-it-yourself kit from a garden center will give readings on pH (how acidic or alkaline your soil is) and the levels of crucial nutrients— nitrogen, potassium, and phosphorus. But for the most accurate and complete results, have your soil tested by your county extension service or state university. They'll analyze a sample from your yard and send you a report, like the one shown at right, detailing the soil's pH, texture, and nutrient levels, and recommending how to correct any deficiencies. And it only costs about $15.
Soil can be tested year-round, but it's best done in the spring or fall. To collect a good sample, dig at least five holes, 6 inches deep by 2 inches wide, in various spots in your yard. As you go, avoid or remove any grass, weeds, thatch, or roots. Mix all the samples together, then put about 2 cups of the mix into a zip-seal bag and send it to the lab.
The more information you give with the sample, the more useful its recommendations will be. Note what kind of turf grass you'll be using; whether the yard gets lots of shade, sun, or foot traffic; or if the soil has been recently disturbed due to construction. Just don't wait until the last minute to have a test done. It takes about two weeks to get the lab's results, and then you'll need some more time to correct the soil, if necessary, before your sod goes down.