Choosing grasses

What’s growing on your field?

Let’s start with grass identification which can be tricky. With a magnifier, the right identification tool and a little experience you will be able to check the identifying features of the grass plant and accurately identify the grass as either a desirable or weedy grass.

These websites have excellent photos and descriptions to help you get started.

Grasses for sports fields

The major cool season grass species used for sports fields include Kentucky bluegrass (Poa pratensis), perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea). These grasses are selected based on their ability to withstand traffic (wear and tear) and stress (from drought and heat), recovery from field use (recuperative ability), good color, desirable growth characteristics, resistance to pest pressure (insects, weeds and diseases) and maintenance requirements.

Characteristics Kentucky bluegrass Perennial ryegrass Tall fescue
Quality Good Good Medium
Establishment Speed Fair Excellent Medium
Wear Tolerance Medium-good Good Good
Recuperative Potential Good Medium Fair
Drought Tolerance Fair-medium Good Good
Disease Tolerance Medium Fair Fair-medium
Insect Tolerance Fair-medium Medium-good Good
Shade Tolerance Fair Fair Good
Fall/spring Color Fair-medium Good Medium

Considerations: Can you supply the maintenance required? Do you have irrigation?

Managers also need to recognize within grass species there can be slight to great varietal differences (i.e. color, spring green up, resistance to pest pressure, etc.) that will impact selection decisions.

Kentucky bluegrass

Kentucky bluegrass (Poa pratensis) is a fine-textured cool season grass which spreads by underground stems called rhizomes. This characteristic gives it the ability to form a dense sod, crowd out weeds and recover from heavy traffic.

Management requirements:

  • Best results when irrigation is available
  • Requires medium level of management
  • Mowing height ranges from 1¼ -3”
  • When seeded alone apply 1-3 lbs./1,000 sq. ft.

Issues:

  • It takes up to 3-4 weeks to germinate and 12-18 months to develop a sod that is dense enough for sports turf use.

There are over 170 Kentucky bluegrasses (KBG) on the market today! Select the variety that matches your management program.

Level of Management Requires Type Comments
Minimal 1-2# of nitrogen per 1,000 sq. ft. per year
Mow at 2½ “ height
Select drought tolerant varieties For non-irrigated sites
High 3-4# of nitrogen per 1,000 sq. ft. per year
Regular mowing
Irrigation
Select aggressive types Ideal for high traffic sites
Produces dense growth
Recovers quickly from traffic
Requires aerification to reduce thatch
Slow to green up, may not be ideal for spring sports

Aggressive types of KBG produce dense growth and recover quickly from traffic. They generally produce more thatch then other bluegrass varieties and will require routine core aerfication programs. During initial establishment and when overseeding, use aggressive types in high traffic areas of football and soccer fields.

Compact types are varieties that have a low, compact growth habit and good resistance to leafspot. They can be mowed at ¾ “if properly watered”. These types are also slow to green up so they may not be ideal for spring sports.

Common type Kentucky bluegrass varieties are not recommended for overseeding programs. These older varieties do not have the attributes of disease resistance and wear tolerance found in newer improved varieties but could be used on very low budget fields.

Perennial ryegrass

Perennial ryegrass (Lolium perenne) is a medium-textured bunch (non-spreading) grass that can germinate within a few days, making it competitive against weed encroachment. It can provide a uniform turf within 2 weeks under ideal conditions.

Management requirements:

  • Select endophyte enhanced varieties
  • Best when mowed at 2½"
  • Prefers sunny, well-drained sites
  • Does not tolerate shade or droughty conditions
  • When seeded alone apply 4-6/1,000 sq. ft.

Issues:

  • Routine overseeding will be required to maintain density and uniformity so turf won’t become “clumpy” in appearance.
  • Check the latest variety performance data to note visual quality color and texture of improved varieties but pay special attention to the disease resistance ratings.

Tall fescue

Tall fescue (Festuca arundinacea) is a bunch-type, coarse leaf-textured cool season grass. In the past some managers have avoided using tall fescue (TF) because of its poor winter hardiness and brown patch susceptibility, but these concerns have largely been alleviated with newer, improved varieties.
 

Endophytes Endophytic fungi are beneficial organisms that produce chemicals that deter surface-feeding insects like chinch bugs and sod webworms and provide improved disease tolerance. Studies have shown that only 20% of the plants in the field need to be endophytic to decrease insect problems so when seeding perennial ryegrass or tall fescue select varieties that contain these endophytic fungi.

Management:

  • Select endophytic enhanced varieties
  • Mow above 2"
  • Regularly overseed to avoid its clumpy growth habit and to outcompete weeds in heavily trafficked sites.
  • Establishment window is from August 15 – September 15
  • When seeded alone apply 6-8/1,000 sq. ft.

Issues:

  • An 8-12 month establishment period will help with long term success of the stand.
  • Use newer varieties. These have improved cold temperature hardiness, excellent drought and wear tolerance and Brown patch resistance.
  • According to the 2010 NTEP results the top performing TF varieties that scored in the top 25% of the ratings included: Bullseye, Falcon V, Monet, Wolfpack II, Faith, Turbo, Catalyst, Firecracker LS and Hemi.

Seeding mixtures and blends

Research conducted at the University of Wisconsin concluded that over a 12 month period under ideal maintenance, the best quality KBG+PRG stand was obtained with Compact Kentucky bluegrass types. The next best performers were the Aggressive Kentucky bluegrass types. Common types were not favored.

Seed mixtures contain 2 or more species, for example Kentucky bluegrass (KBG) and perennial ryegrass (PRG).

Although Kentucky bluegrass fields make up the best quality sports fields most have been seeded as a Kentucky bluegrass and perennial ryegrass mix, usually an 80:20 mix. Perennial ryegrass should not make up more than 20% of the mix in a new seeding because it is not as wear tolerant or winter hardy as KBG and because over time the PRG could become the dominant species.

Seed blends contain 2 or more varieties of the same species. A dense turf stand can be achieved by blending improved varieties. Use a couple of the highest quality varieties that contain the desired characteristics (wear tolerance, recuperative potential, resistance to stress, establishment speed, color, etc.) desired for your situation.

Sample seed label

Seeding rates

Seeding rates depend upon the species and whether they are planted alone or in combination with another species. The seed label lists the percentage weight of each species in the mixture. Another factor to keep in mind is seed number. There are approximately 1.5 million seeds in a pound of KBG seed and 250,000 seeds in a pound of perennial ryegrass. So seeding a mixture containing 70% PRG and 30% KBG would actually result in a 50:50 mix of KBG and PRG.

Seed or Seed Mixture % Weight Seed Rate lbs./ 1,000 sq. ft. Time between Seeding and Play
Kentucky bluegrass (KBG) 100% 1-3 9-12 months
Kentucky bluegrass (KBG) +
Perennial ryegrass (PRG)
80-90% +
10-20%
3-4 6 months
PRG should not make up more than 20% of the mixture unless you want predominately a PRG stand
Kentucky bluegrass (KBG) +
Perennial ryegrass (PRG)
50%
50%
3-5 3 months
Perennial ryegrass (PRG) 100% 4-6 <3 months
Tall Fescue (TF) 100% 6-8 9 months
Does not mix well with PRG. Should be at least 85-90% when mixed with KBG.

Pure live seed is the percent (%) of seed that is pure and viable and capable of germinating. For example if you had a blend of Kentucky bluegrasses at 95% and the germination listed is 85% the pure live seed capable for germinating would be 81%: (.95) (.85) = 81%

You need to buy ~20% more seed to provide the recommended amount.

Seeding strategies

Establishing a new seeding

The best time to establish a new seeding is between mid-late August and mid-September (August 15 –September 15). Kentucky bluegrass and tall fescue are better seeded in August, while perennial ryegrass can be seeded well into September. During this period soils are still warm, weed pressure is lower than it is in spring and the likelihood of rain is high. You can establish grass in the spring but success is influenced by variable weather, higher weed pressure and soil water content.

Steps:

  1. Avoid soil compaction issues by minimizing the use of heavy equipment on a site to be seeded.
  2. Till into the upper 6-8” of soil, organic matter (i.e. good quality compost) and lime if needed.
  3. Complete final surface grade.
  4. Use soil test results to determine the amount of phosphorus and potassium to apply. Use a York rake or similar tool to incorporate fertilizer into the upper 1-2” of soil.
  5. Lightly rake the surface smooth and apply high quality seed at the recommended rate by applying ½ the seed in one direction and the other ½ in the opposite direction. Drop spreaders and rotary spreaders can be used under calm conditions. Incorporate the seed into the upper ¼ - ½” of soil. Lightly roll to ensure good soil to seed contact. Using a slicer or slit seeding is also commonly used.
  6. Broadcasted seedings should be mulched to prevent soil erosion and increase establishment success, especially if irrigation is not available. Use weed-free straw and apply 50-90 lbs. per 1,000 sq. ft. to cover to about ½” thickness.
  7. Lightly water daily until the first mowing.
  8. Mowing can begin once grass reaches about 3¾” on a field that will be mowed at 2½”.
  9. 3-4 weeks after germination apply ½ lb. of nitrogen per 1,000 sq. ft. or up to 1 lb. if using a 50% slow release source. 

Overseeding small areas for quick cover

Broadcast perennial ryegrass at 4-6 lbs. of seed per 1,000 square feet.

Providing faster turf cover using pre-germinated seed

Mike Andresen, athletic field manager at Iowa State University, uses the following procedure on heavily used fields when faster turf cover is desired.  

  1. Begin with 50 lbs. of seed in a nylon bag.
  2. Place the bag in a 50 gallon barrel and cover it with water and then cover the barrel with plastic.
  3. Remove the plastic and change the water each day.
  4. Aerify the area to be seeded on the 4th day. Empty the water from the barrel and spread  seed by hand on the aerified area.
  5. Apply a starter fertilizer and a recommended fungicide to control Pythium in the summer or Gray Leafspot if seeding in August.
  6. Use a verticutter to slice in seed and break up plugs.
  7. Lightly rake the area and roll with a medium-weight roller (200-500 lbs.).
  8. Water the area until establishment is complete.

Dormant seeding for early spring turf cover

Dormant seeding is done in late fall or early winter and can increase the chance of having improved turf cover in the spring on soils that are poorly drained or soils frequently too wet to work. Dormant seedings can germinate 2-3 weeks earlier in the spring than conventional spring seeding.  

However, to improve your chance of success the seeding must take place late in the season, when the average air temperature is below 50° and when there is no chance of seed germination, which usually occurs when the soil temperature is above 50°.  Check the soil temperature at the 1” depth to make sure it is not higher than 40-45°. The ultimate success of a dormant seeding is determined by the winter conditions. You can expect some seed mortality so the seeding rate at this time should be increased 50%. When seeding KBG apply 3-4 lbs. per 1,000 sq. ft. On areas that may be prone to erosion mulching is suggested to help stabilize the soil.

Another window of opportunity for dormant seeding would be during periods when the night time temperatures reach freezing, the day time temperatures warm up and there is no snow cover.  These conditions allow for the broadcasted seed to work its way into the soil. In the Northeast this time period occurs around late February or early March.

Sports turf seeding schedule

Adapted from Dave Minner, Iowa State University

  March April May June July August September October November
Football
Practice
Field
C
PR
C
PR
D
PR
   

 

C
PR
C
PR
D, Dormant
KB + PR
Fall
Football
  D,B
KB once
D,B
KB+ PR
      C,B

Weekly

C,B C,B
Final seeding KB+PR 
Multi-Use
Fall Football +
Spring Soccer
C,B,D
KB
C,B,D
Weekly
KB
C,B,D
Weekly
PR
D
once
    C,B,D
Weekly
KB+PR
C,B,D
Weekly
KB+PR
D, Dormant
Once
KB+PR 

Shaded areas indicate times when fields are in use.
Species:  KB= Kentucky bluegrass, PR= Perennial ryegrass, TF= Tall fescue
Method:  B= broadcast seed, C= cleat-in seed, D= drill seed

When to use sod

When there is not time to wait for grass to establish and turf cover is needed sod ( mature turf cover) can provide quick cover on heavily worn areas such as goal mouths. Sodding can be done any time the ground is not frozen.

Start with good quality thin-cut sod or thick-cut sod that was grown in soil similar to the existing soil. Thin-cut sod, which usually has about ¼ - ½” of soil, is easier to handle and will root faster than thick cut sod.

Thick-cut sod can have as much as 1-2” of soil which makes it much heavier to handle and contributes to  higher  trucking costs. However, once laid properly it is ready for play immediately.

Use sod to quickly repair high-traffic areas such as goal mouths (above).

Consider tall fescue sod

If you are expecting high traffic and will not be able to provide regular fertilization and irrigation after establishment consider a tall fescue dominated sod (at least 90% TF) with some Kentucky bluegrass to help knit the sod together.

Be sure to prepare the soil before the sod arrives!

  • If you have a clay subsoil consider adding a high quality compost (yardwaste or biosolid)
  • Till compost into 4-6” of soil
  • Properly grade and level the area to maximize surface drainage

Sod should be protected during transportation.  Remember sod that is left too long on the truck runs the risk of heating up due to respiration by both the turf and microorganisms. The center of the sod stack could reach very high temperatures causing turf damage or death. So avoid leaving sod in the sun and place it in the shade or be prepared to lay the sod when it arrives.

Lightly moisten the soil if the soil is dry at the time of sodding. The sod should be placed in a brick-like pattern, staggered so the edges do not line up.  Minimize the number of edges that are exposed that could lead to desiccation.  A light rolling could be helpful at this time to eliminate any air pockets. Watering is key now and important in promote rooting.  Check to make sure that the watering has gone deeper than just the surface and has thoroughly wetted the underlying soil. Keep the soil moist and periodically check on sod to see how it is rooting.  Avoid traffic until the sod is rooted which could take 1 week or so. To avoid layering problems once the turf is rooted core cultivate and remove the cores.  Mowing can begin once the area is firm enough to handle traffic. A light application of nitrogen (½ lb./1,000 sq. ft.) may be beneficial 3-4 weeks after the sod has been laid.