Seeding: New Life for Your Lawn

Establishment of turfgrass areas is most commonly accomplished with seed, although sod can be used. Sod offers the advantage of an “instant lawn,” whereas seed takes much longer to produce green turf. Establishment with seed is much less expensive and is surprisingly less complicated than with sod. But in no way is establishing a lawn with seed an easy task that should be taken lightly. Following proper establishment procedures can produce healthy turf that one can be proud of for many years to come.

Time of Seeding

The best time to seed a lawn is in the late summer to early fall. Adequate soil moisture, warm soil and limited weed pressure allow for excellent seedling growth. Between August 15 and September 15 is the 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. 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. Establishment in the spring is possible but not as effective as fall seeding.

Watering

Seedlings are very susceptible to desiccation, and the seed bed should not be allowed to dry. A newly seeded lawn will need to be irrigated two to four times daily depending on the weather. Enough water should be applied to moisten the top 1 to 2 inches of the soil profile, but avoid over-watering and saturating the area. Once the seedlings are 2 inches high, gradually reduce the frequency of irrigation and water more deeply. After the turf has been mowed two or three times, deep and infrequent irrigation is most effective.

Mowing

Mowing a new lawn will encourage the turf to fill in quickly. Mowing should begin when the first few seedlings are tall enough to mow. You may only mow 10% of the plants in the first mowing, 20% to 30% of the plants in the second mowing, and so on. Most wait too long to mow a newly seeded lawn, so mow early and often. Initially mow Kentucky bluegrass, perennial rye and fine fescue at 1.5 inches, and tall fescue at 2 inches. After the first three to four mowings, you can adjust your mower to the permanent mowing height, which is 2.5 to 3.5 inches for Kentucky bluegrass, perennial rye, and fine fescue, and 3 to 4 inches for tall fescue. As always, never remove more than one third of the grass blade at any one mowing.

Fertility

New seedlings have poorly developed root systems. Thus, they cannot effectively absorb nutrients from the soil. Therefore, it is important to fertilize frequently after seeding to encourage establishment. Apply 0.75 to 1 lb. N/1,000 square feet four to six weeks after germination, and again eight to 10 weeks after germination. Assuming seeding in mid-August, these applications would be in mid- to late September and again in mid- to late October.

Weed Control

There is little weed pressure in the fall, so weed control may not be needed. Broadleaf weeds may become a problem in the fall, but these can easily be controlled with a broadleaf herbicide application in October or November (after the third or fourth mowing). Annual grasses such as crabgrass can easily be controlled with pre-emergent herbicides applied in the spring.

Spring Seeding

The best time to seed a lawn is in the fall (mid-August to mid-September). Seeding in the spring is very difficult and often unsuccessful. However, there are circumstances that do warrant a spring seeding:

  • Thin turf due to winter damage.
  • Poor turf density due to poor recovery from previous year’s problems (e.g., grub damage, drought damage, etc.)

To Make Your Spring Seeding Most Successful, You Must:

  • Seed as early in the spring as possible to maximize the competition of turfgrass over crabgrass. Dormant seeding or early-April seeding is preferred.
  • Maximize seed-to-soil contact through good soil preparation.
  • Irrigate often as soon as temperatures favor germination (soil temperatures above 55º F). As root systems develop, gradually reduce frequency, but increase duration of irrigation. Continue irrigation throughout the summer until an adequate root system is established.
  • Control weeds in the lawn, because spring-germinating weeds will out-compete the desirable turfgrass (and may kill the turfgrass).

Dormant Seeding

If a spring seeding is necessary, consider doing it before the frost comes out of the ground. This is defined as “dormant seeding,” because the seed will lie dormant until the soil temperatures warm in April or May. Depending on your location in Indiana, dormant seeding can be done as early as Thanksgiving and as late as March. The benefit of dormant seeding is that as the soil heaves and cracks during the winter, crevices are created for the seeds. This creates ideal germination conditions. Additionally, dormant seeding is easier to schedule than spring seeding, because spring rains make it difficult to seed after March in Indiana.

Weed Control Guidelines

  • Perennial grassy weeds (nimblewill, creeping bentgrass, etc.) are not effectively controlled in the spring with glyphosate (Roundup or Kleen Up). Plan this type of renovation for the late summer.
  • Avoid using broadleaf herbicides in newly seeded areas until the new seedlings have been mowed at least three times.
  • Avoid using pre-emergent crabgrass controls (except those containing siduron) at the same time as a spring seeding. As a general recommendation, delay the use of these materials until the new seedlings have been mowed four to eight times, depending on the herbicide. Check the label of the specific crabgrass control material for the exact recommendations. As mentioned earlier, siduron is an exception to this rule. It can be used at the time of seeding, but will only control crabgrass for three or four weeks.