Seeding and Sodding Tips

When to Seed

Late summer is the best time to establish Kentucky bluegrass, creeping bentgrass, tall fescue, and perennial ryegrass from seed. Between August 15 and September 15 is optimum seeding time in the northern half of Indiana, from September 1 to September 30 is optimum in the southern half of Indiana. It is critical to seed as early as possible within these windows. You likely cannot seed too early and even when seeding within these windows, waiting one week later to seed may mean the stand will take two to four additional weeks to mature. The primary reason that late-summer seeding is preferred is that it maximizes the time for the grass to establish before it faces the heat and stress of next summer. Even though a late-summer seeding requires frequent irrigation, limited weed and disease pressure, warm soils, and moderating air temperatures encourage quick establishment.

Springtime Seeding

Late summer (August) is easily the best time to seed cool-season grasses, but sometimes turf must be seeded in the spring. The following points should help improve the success of spring seeding:

1. Seed as soon as possible so the seed is in the ground and ready to germinate as soon as the soil temperatures rise.
2. Improve the seed-soil contact by raking or disturbing the soil before seeding. After seeding, a light raking will further mix the seed and soil or a light rolling will push the seed into better contact with soil.
3. Water lightly to keep the seedbed moist as soil temperatures warm to 50° and the seed starts to germinate.
4. Avoid any pre-emergence crabgrass or post-emergence broadleaf herbicide applications to the seeded areas until the seedlings are established and mowed at least 3 or 4 times, which might be May or later depending on the weather. The exception to this is any pre-emergence products containing siduron. Since all herbicides have slightly different restrictions, be sure to check the label of your specific product for specifics.
5. Since the seedlings will not develop a good root system until next fall, keep the newly seeded areas well-watered all summer.

Zac Reicher, Professor/Turfgrass Extension Specialist

Sod Selection and Installation

Some things to consider when purchasing sod include thickness, soil type, weed content, and freshness. Sod is generally cut to a depth of 0.25 to 0.5 inches and properly harvested sod should contain surprisingly little soil. Thinner sod is easier to ship and handle and will also root faster. However, thin sod requires more frequent irrigation during establishment. Choose sod that contains soil similar to the soil found on the site. This will help avoid creating layers that could reduce rooting depth and water flow. Weed content is an obvious consideration. If possible, ask to see the area from where the sod will be harvested. This will also give some idea of the health of the sod. Finally, the sod should be fresh when it is delivered to the site. Many sod growers cut to order and then deliver the sod within the same day.

It is very important not to let the sod get too dry. If you cannot lay the sod immediately after delivery, you may need to sprinkle with water to keep the outer rolls moist. Also, lightly moisten the soil where the sod is to be laid, but avoid over-watering the work area. Begin laying the sod in a brick-like pattern so that the ends are staggered. This will reduce the number of long seams. The edges of the sod should be in contact with each other. Exposed edges can dry quickly and die. It is also important to avoid stretching or overlapping the sod. A piece of sod that has been stretched is likely to shrink latter forming gaps and exposed edges. If there is a slope, start at the bottom and run the sod perpendicular to the slope. A steep slope (10% or more) may require pegging or stapling the sod in place. Wooden pegs can be pulled out late after the sod is rooted down, but biodegradable sod staples do not have to be removed.

The final steps in sod installation are to lightly roll and then thoroughly water the sod. Rolling is not meant to remove underlying irregularities in the soil but to insure good sod-soil contact and remove any air pockets without compacting the soil. Thoroughly water the sod immediately after rolling. Keep traffic off the sod until it is well-established.

Glenn Hardebeck and Zac Reicher
Purdue University Turfgrass Specialists