Turf Tips
08/24/2010

Now is the time to seed lawns and other turf areas

Timing

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 optimum seeding time in the northern half of Indiana, and September 1 to September 30 is optimum in the southern half of Indiana. Although our soils are slightly warmer than their normal temperature this time of year we are still recommending that turf managers and homeowners seed during the window recommended above. The seeding window may be a little larger (longer) this year with warmer soil temperatures now and with forecasts showing a possibility of a warmer than normal September.

It is critical to seed as early as possible within these windows. Even when seeding within these windows, waiting one week to seed may mean the stand will take 2 or more additional weeks to mature. For more information see, Establishing a Turfgrass Areas From Seed.

Selection
It is important to purchase quality grass seed. According to state law, each seed bag must be labeled as to what exactly is in the bag. Make sure that the seed was tested within the last six months as well as checking that the germination rate is 85% or better. Also, make sure that the seed label specifies the cultivar that you had in mind and contains less than 0.3% weed seed and no noxious weeds. Other things to look for are less than 5% inert matter and less than 0.5% of any other crop. For more information see, Purchasing Quality Grass Seed for your Lawn.

Seeding
Seed should be applied using a drop spreader because rotary spreaders do not disperse the seed uniformly. However, spreaders typically do not come with calibration information about seeding turfgrasses. The easiest way to apply seed uniformly is to set the spreader adjustment very low, sow one half of the seed in one direction, and then sow the other half at right angles to the first direction of seeding. It might take three or more passes over your lawn in a single direction, but it is well worth the time to get a uniform seeding. Seeding rate recommendations are presented in Table 1.

Table 1. Recommended seeding rates for lawns in Indiana.


Seed Blend or Mixture

Seeding rate

lbs./1000 ft2

lbs./acre

100% Kentucky bluegrass

1.5-2.0

65-87

85-90% Kentucky bluegrass + 10-15% perennial rye

3.0-4.0

130-175

50-70% Kentucky bluegrass + 30-50% fine fescue

4.0-5.0

175-220

100% tall fescue

6.0-8.0

261-348

90% tall fescue + 10% Kentucky bluegrass

5.0-7.0

220-305

Mulching
While mulching is not essential for lawn estab­lishment, it will help prevent erosion on sloped sites, conserve moisture, and reduce seed loss from wind, birds, and washing. Weed-free straw is a good choice for mulching. One square bale of straw typically covers 1,000 ft2. The tendency for most homeowners is to apply too much straw. Applying straw too thick can be detrimental to establishment and require removal after seedling germination. About 50 percent of the soil should be visible after mulching. There are many other erosion blankets available to help prevent erosion and increase soil temperature and increase moisture holding capacity. These materials are often constructed out of jute, coconut fiber, excelsior, polypropylene, and paper based products. Some blankets are permanent, while others are to be removed after seedling germination. Read and follow the manufacturer instructions for best results.

Watering
Seedlings are very susceptible to moisture stress during the first few weeks after seeding. The upper 1 inch of soil should be kept moist with frequent irrigations for the first two or three weeks after planting. After the seed germinates and seedlings develop, the lawn should be watered less often. Eventually, the lawn should be water deeply and infrequently only when the plant shows signs of water stress.

Hydroseeding
Hydroseeding is the process where professionals apply seed in a water, fertilizer, and mulch slurry. This profess was developed in 1953 by Charles Finn in order to help establish turf on roadsides. This process is especially helpful in areas with difficult equipment access such as sloped areas. Wood or paper based products are typically used as a mulch to help retain moisture. Professionals also commonly add tackifiers or polymers to help increase uniformity, and the stability of the hydromulch. The key ingredient in hydroseeding is the seed so it is important to use improved cultivars that are well adapted to your location.

Aaron Patton, Turfgrass Extension Specialist


Send corrections, suggestions, and comments to biehlj@purdue.edu