Seeding in spring is difficult and unsuccessful if not done correctly. However, there are many in Indiana who didn't seed last fall but still need to seed this spring to help fill in thin areas from last summer's drought. The following circumstances that warrant a spring seeding:
- Thin turf due to winter damage
- Poor turf density due to poor recovery from previous year's problems, i.e., grub damage, drought damage, etc. This is the case in 2013 due to heat and drought in 2012.
- Construction of a new building.
If a spring seeding is necessary, it is best done as early as possible. Ideally, early spring seeding should actually take place in winter before the ground thaws. Although it is not necessary to seed before the ground thaws it may make seeding more easy as soils are often soft and moist in the spring which may make it more difficult to seed certain areas, especially with heavier equipment.
Seed planted now will germinate in mid to late April as temperatures warm. Although any cool-season grass can be seeded in the spring, spring seedings are more successful with tall fescue and perennial ryegrass than with Kentucky bluegrass due to the faster germination rate and better seedling vigor of perennial ryegrass and tall fescue compared to Kentucky bluegrass. If Kentucky bluegrass is seeded in the spring consider using a mixture of tall fescue: Kentucky bluegrass (90:10, weight: weight) or a mixture of Kentucky bluegrass: perennial ryegrass (such as 80:20, weight: weight). Seeding Kentucky bluegrass alone will result in marginal bluegrass establishment due to the slow germination and vigor of the seedlings and increased competition from crabgrass.
Fertilizing seedings properly is important. New turfgrass seedlings have poorly developed root systems and thus they cannot effectively take up the nutrients from the soil. Therefore, it is important to fertilize after seeding to encourage establishment.
To help the turf establish, apply a "starter fertilizer" at seeding to enhance seedling root development. Starter fertilizer is high in phosphorus which is listed as the second number in the analysis on the fertilizer bag. For instance, a 16-22-8 fertilizer contains 22 percent P2O5. Apply the fertilizer according to the label directions would should supply at least 1.0 lb. P2O5 /1000 ft2. This application will likely include nitrogen (first number in the fertilizer analysis), which will also help the turf develop an extensive fibrous root system that is better able to take up nutrients and obtain water.
Source: Purdue Turf Tips