Seed or sod?

Are you considering installing a new lawn, or renovating a worn one? Then one choice you are faced with is whether to use seed or sod. With either, your lawn will establish more easily with proper prior soil preparation.

Begin with a soil test to determine what nutrition you may need, and if the soil pH or acidity needs adjusting. Soil test kits are available from local Extension offices and many complete garden stores.

Rototill the soil well to four to six inches, raking off any rocks and other debris. This will incorporate any fertilizer you may have applied, and usually kill off most annual weeds. Try to do this before annual weeds go to seed. Perennial weeds have roots that remain in the soil. Tilling the soil only breaks roots into many pieces which result in more plants. The quick way to control such weeds is with a post-emergent herbicide (which kills weeds that have already emerged). If using a herbicide, make sure to read and follow label directions. Organic ways to control perennial weeds are to cover the area with black plastic for a season prior, or use cover crops for a year or two prior to beginning your lawn.

If you plan to start your lawn from seed, keep in mind that the best time to plant grass seed is late April through May and late August to early September. Spring and fall provide favorable growing conditions for cool season lawn grasses.

Grass seed can be spread over the ground with a fertilizer spreader. Use about four pounds of seed per 1,000 square feet of area, unless other amounts are recommended on the bag or by your dealer. Apply half the amount in one direction, the other half at right angles to ensure uniform coverage.

Drag a lawn rake over the seeded area to mix the seed into the soil surface. Use a roller (these can be rented) to firm the seeds into the soil and improve germination. Watering is critical for new seedings. Sprinkle the ground lightly several times a day to keep the soil surface cool and moist. As the grass begins to grow, water less often but more each time.

Cover the new seeding with straw, using one bale for each 500 square feet of area. When the grass is about two inches tall, remove half the straw. The rest can be allowed to decompose naturally. Begin mowing when the grass is two to three inches tall. The mower blade must be sharp. Dull blades will pull the young plants out of the ground rather than cut the leaves. A newly seeded lawn will fill in faster if mown more often.

Fertilize with a lawn fertilizer when the plants are two inches tall. Be sure to water in the fertilizer if the instructions on the bag say to do so. Water so that an inch of water per week is applied to the new seeding.

If you are renovating an existing lawn, you can overseed it without starting all over if it contains less than 50 percent weeds. As with starting a new lawn, begin with fertility according to a soil test. Use a power rake or verti-cutter to remove weeds and thatch. Most important is to use a blend of improved seed varieties that can withstand insects and diseases, and can outgrow weeds. Once seeds are applied as with a new lawn, use a slit seeder to work them into the existing lawn. You can rent this equipment at complete rental stores, or hire a professional.

Sod can provide a lawn in a shorter time than seed. A prime disadvantage of sod is the limited number of grass species included in sod mixes. Most sod is a blend of several Kentucky bluegrass cultivars.

Sodding can be done when the soil is dry enough to work, and the sod will have enough time to root before winter. Do not lay sod during dry weather if water cannot be provided. Rolled-up sod heats up, and this heat can kill the sod. To avoid injury, lay the sod within 24 to 48 hours after it was cut.

Do not lay sod on hot, dry soil. Moisten the soil to a depth of six inches, then lay the sod in a pattern that looks like bricks in a wall. This can be done by starting alternate rows with half a roll of sod rather than a full one. The edges of the rolls should be touching firmly to prevent the sod from drying out. Once all the sod is laid, roll it to remove air pockets and ensure roots are in good soil contact. Hold sod laid on a slope in place with wooden stakes.

Water the sod immediately after rolling. Unlike with seeds, water heavily every day after laying the sod until the roots have begun growing into the soil—often two to three weeks. Then reduce watering gradually. A sodded lawn should not need fertilizer for the first season.

Dr. Leonard Perry is Extension Professor, Department of Plant and Soil Science at the University of Vermont. Visit his website at