Planting a lawn in the summer is more difficult because of hot weather, but it's not impossible. Because they grow best in hot weather, warm-season grasses are easier to establish in the summer than cool-season grasses. With adequate water, you can establish warm-season grasses from seed or both warm- and cool-season grasses from sprigs, plugs or sod.
Make sure the soil is ready before planting a lawn with seed, plugs, sprigs or sod. Remove weeds and large rocks, then spread a 1- to 2-inch layer of organic matter like well-rotted manure, compost or peat moss over the soil surface. Till to a depth of 5 to 7 inches. Water the soil well right before planting.
Seeding a Lawn
Whether or not you should plant grass seed in the summer depends on the type of grass and climate location. Kentucky bluegrass (Poa pratensis), tall fescue (Festuca arundinacea) and other cool-season grasses are unlikely to survive planting in summer heat. These grasses, which are both hardy in U.S. Department of Agriculture plant hardiness zones 2 to 7, actively grow in cool weather and are best planted in the fall.
Warm-season grasses like Zoysia grass (Zoysia spp.) and Bermuda grass (Cynodon spp.) actively grow during the warm months of the year. Zoysaia grass is hardy in USDA zones 6 through 9, and Bermuda grass is hardy in zones 7 through 10. Warm-season grasses can be seeded in the summer months.
Step 1: Sow
Use a rotary or drop spreader to scatter warm-season grass seed evenly across the lawn surface. Apply half the seed working in one direction across the lawn, then the rest of the seed at right-angles to the first seeding.
Step 2: Cover
After planting, lightly cover seeds with 1/4 to 1/2 inch of loose topsoil. Alternately, go over the lawn surface with a rake to work the seeds into the top 1/2 inch of soil. Go over the lawn again with a lightweight roller to firm the soil.
Step 3: Mulch
Cover the seeded surface with a thin layer of weed-free hay or straw. About one-half to three-quarters of the soil surface should be covered when you are done.
Step 4: Water
The soil has to stay moist for seeds to germinate, especially in the hot summer months. Water the newly planted lawn two to three times a day in small quantities for about two weeks. Applying too much water at once will wash seeds away. After the seedlings are growing, you'll still need to keep the soil moist, but you can water less often and apply larger quantities of water each time.
Planting Plugs and Sprigs
It's much easier to start lawns in the summer from live grass plants than from seed, but you still have to be careful that the plants don't dry out. Warm-season grass will be easier to establish in the summer than cool-season grass, unless you're having a cool or rainy summer. In locations with drought or unseasonably hot weather, you might want to hold off on sprigging or planting plugs until fall.
Step 1: Dig
For plugs, dig individual holes 6 to 12 inches apart. For sprigs, dig rows 2 inches deep and 6 to 12 inches apart. The closer you make the holes or rows, the faster the lawn will fill-in with grass.
Step 2: Plant
Plant plugs in the holes so they are level with the ground, then firm soil around them. For sprigs, place them in the furrows so that the nodes (the part of the grass piece that forms roots) are touching the soil, then fill-in the furrows. Go over both sprigs and plugs with a light roller after planting.
Step 3: Water
Keep the plugs or sprigs constantly moist, but not soggy, until roots develop. In hot summer weather you'll need to water once or twice every day for the first one to two weeks. After that, you can cut back to watering just enough to keep the soil from drying out. If plants start to wilt, increase watering.
Laying New Sod
Using sod is probably the best way to plant a lawn in summer, but it is not without its problems. You'll have to water frequently to keep the grass alive in the hot weather, but hot weather combined with humidity from frequent watering can lead to disease formation. If you lay sod in hot weather, monitor the lawn carefully to avoid letting soil dry out from underwatering or become soggy from overwatering.
Step 1: Lay
Once the sod arrives, place it in a shaded location and spray it with water every time it starts to dry out while you're planting. Start along one edge of the lawn, and lay the sod in rows, staggering the joints in each row as if you were laying bricks. Make sure the sod pieces are touching, but do not overlap.
Step 2: Roll
After laying, completely soak the sod by applying at least 1 inch of water over the whole lawn. Roll the sod with a water ballast roller to make sure the roots are in contact with the soil.
Step 3: Water
Keep the sod moist for the first seven days by applying small amounts of water two to three times a day. You want to keep the soil moist so roots can establish but not soggy enough to cause disease. Continue watering regularly to keep the soil from drying out until the grass is actively growing.