Turfgrass Seeding Recommendations for the Pacific Northwest

Publication Date: 
12/01/2010

A PACIFIC NORTHWEST EXTENSION PUBLICATION • PNW299

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Washington State University • Oregon State University • University of Idaho

Introduction

Scientists at Washington State University, Oregon State University, and the University of Idaho have conducted turfgrass variety evaluation trials in the Pacific Northwest for over 50 years, and continue to cooperate in local, regional, and national testing programs to provide current information on the performance of most turfgrass species marketed today. Data from these trials are used as the basis for recommendations to establish turfgrass under common and complex field situations. The National Turfgrass Evaluation Program (NTEP) lists all the data collected from around the country at www.ntep.org. For best results, use data from the research site closest to your turfgrass management location.

The blends, mixtures, and rates in this publication are current recommendations for homeowners, seed companies, salespersons, and turfgrass managers based in Washington, Oregon, and Idaho. No variety names are included because of the variability of adaptation for specific regions of the Pacific Northwest and the constant changes as to which cultivars may be available to turfgrass managers. If you have questions about particular varieties, contact your local Extension personnel or go to the website of the nearest turfgrass program.

Turfgrass Seed Characteristics

Seeds per pound.Turfgrass seeds are different sizes. The number of seeds per pound varies widely among grass genera, species, and even varieties. Seed size influences the seeding rate required to produce comparable stands; for example, bentgrass is seeded at a lower seeding rate than tall fescue. Table 1 compares the seed size of most common Pacific Northwest turfgrasses.

Germination and purity. Germination of a seed lot refers to the amount of pure seed that is viable, or the percentage of seed that will germinate under ideal laboratory conditions. Purity is the freedom from matter other than the seed itself. Germination and purity are expressed as a percentage of the total seed in a particular lot. The germination and purity percentage can vary and still meet state certification standards and federal seed laws.

Pure live seed (PLS) is the percentage of seed from a particular variety that will germinate and produce viable seedlings. PLS is calculated by multiplying the percent germination by the percent purity. For example, if 80% of Lot No. 1 germinates and is 85% pure, while 82% of Lot No. 2 germinates and is 98% pure, the PLS of Lot No. 1 is 68%, while the PLS of Lot No. 2 is 80%. The seeding rate of Lot No. 1 would need to be increased by more than 12% to obtain the same number of PLS as in Lot No. 2. Turfgrass seeding rates (Tables 2–11) are expressed on a PLS basis. Therefore, to determine how much seed to purchase for the best stand of grass, adjust the seeding rate according to the percent PLS of each seed lot.

Table 1. Average number of seeds per pound for common Pacific Northwest turfgrasses.

GrassSeeds
Streambank wheatgrass (Elymus lanceolatus ssp. lanceolatus)156,000
Tall fescue (Festuca arundinacea and Lolium arundinaceum)178,000–234,000
Perennial ryegrass (Lolium perenne)210,000–270,000
Crested wheatgrass (Agropyron cristatum)311,000
Red fescue (creeping) (Festuca rubra var. rubra)365,000
Chewings fescue (Festuca rubra var. commutata)449,000
Sheep or Idaho fescue (Festuca ovina or Festuca idahoensis)530,000
Hard fescue (Festuca ovina var. duriuscula)592,000
Kentucky bluegrass (Poa pratensis)1,022,000–1,758,000
Colonial bentgrass (Agrostis tenuis)6,130,000
Creeping bentgrass (Agrostis palustris and stolonifera)6,130,000
Velvet bentgrass (Agrostis canina)8,247,000

Table 2. Seeding recommendations for new golf course putting greens.

GrassSeeding rate (lb/1,000 ft2)
Creeping bentgrass varieties*1–2
Velvet bentgrass1–2
*See the websites listed at the end of this bulletin for the most recent bentgrass variety rankings from WSU, OSU, UI, and NTEP.

Table 3. Seeding recommendations for new golf course teeing grounds.

GrassSeeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Perennial ryegrass5–8R*R
Kentucky bluegrass3NR**R
Creeping bentgrass2RR
Perennial ryegrass4NRR
  -plus Kentucky
    bluegrass
1.5NRR
Perennial ryegrass5RR
  -plus
    bentgrass
1RR
*Recommended.
**Not recommended unless as part of a mixture.

Table 4. Seeding recommendations for new golf course fairways.

Grass*Seeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Kentucky bluegrass (blended varieties)3NR**R***
Kentucky bluegrass (blended varieties)2NRR
  -plus creeping red,
    Chewings, or hard
    fescue
1NRR
Kentucky bluegrass2NRR
  -plus perennial ryegrass2NRR
Perennial ryegrass (blended varieties)5–8RR
Perennial ryegrass2RR
  -plus creeping red,
    Chewings, or hard
    fescue
2RR
  -plus colonial
    bentgrass****
0.5RR
Perennial ryegrass1RR
  -plus creeping red,
    Chewings, or hard
    fescue
1RR
  -plus Kentucky bluegrass1RR
  -plus colonial
    bentgrass****
0.5RR
Creeping red, hard, or Chewings fescue3RR
  -plus colonial bentgrass0.75RR
Perennial ryegrass3RR
  -plus colonial
    bentgrass****
0.5RR
*Never plant bentgrasses on fairways in eastern Washington, eastern Oregon, or Idaho unless mowing heights are maintained at less than 5/8 inch and fungicides are used to control snow mold.
**Not recommended.
***Recommended.
****Colonial bentgrass will most likely dominate when added to these mixtures. Take care to match the grass colors and growth habits to avoid a mottled and bouncy appearance.

Table 5. Seeding recommendations for new athletic fields.

GrassSeeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Kentucky bluegrass (blended varieties)3NR*R**
Kentucky bluegrass (blended varieties)2RR
  -plus perennial
    ryegrass
2RR
Perennial ryegrass (blended varieties)5–8RNR
*Not recommended for lower maintenance fields.
**Recommended.

Table 6. Seeding recommendations for new home lawns, parks, and cemeteries*.

Grass**Seeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Kentucky bluegrass (blended varieties)3NR***R****
Kentucky bluegrass (blended varieties)1.5NRR
  -plus creeping red,
    Chewings, or hard
    fescue
1.5NRR
Kentucky bluegrass (blended varieties)2RR
  -plus creeping red,
    Chewings, or hard
    fescue
1RR
  -plus perennial
    ryegrass
1–2RR
Perennial ryegrass4RR
  -plus creeping red,
    Chewings, or hard
    fescue
2RR
Creeping red, Chewings, or hard fescue3RNR
  -plus colonial
    bentgrass
1RNR
Turf-type ryegrass5–8RNR
Colonial bentgrass0.75–1.5RNR
Creeping red, Chewings, or hard fescue3RR
Tall fescue8limited use; must be overseeded to maintain stand densityR
*In cemeteries with large numbers of existing or planned trees, plant seed mixtures containing 35–50% creeping red, Chewings, or hard fescues by weight.
**Maintain lawns seeded with fine fescue and bentgrass in western Washington and western Oregon at 1/2–3/4 inch mowing height for maximum beauty and thatch control. Seeding eastern Washington, eastern Oregon, or Idaho lawns to bentgrass is not recommended.
***Not recommended.
****Recommended.

Table 7. Overseeding recommendations for putting greens and teeing grounds.

GrassSeeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Putting greens
  Creeping or
  velvet
  bentgrass
1–2R*R
Tees
  Kentucky
  bluegrass
3NR**R
  Perennial
  ryegrass
6RR
  Perennial
  ryegrass
6RR
    -plus any
      bentgrass
1RR
  Any
  bentgrass
1–2RR
*Recommended.
**Not recommended.

Seed tag. In addition to germination, purity, and turfgrass species, the seed tag must show percentages of weeds, other crop seed, inert matter, and the date of the last germination test. If you buy Washington, Idaho, or Oregon certified seed, you can be confident that particular lot meets good seed standards. Some noncertified seed may be better than average quality certified seed, but you cannot always be certain of its genetic origin.

Blend. Seed blends contain two or more varieties of a single species.

Mixture. Seed mixtures contain two or more turfgrass species. An example of a simple mixture is one variety of Kentucky bluegrass combined with one variety of perennial ryegrass, while a complex mixture would be blends of several Kentucky bluegrass varieties and several perennial ryegrass varieties. In Tables 3–8, the recommended mixtures are identified with “plus” between species.

Overseeding Turfgrass Areas

Overseeding is the application of seed to depleted turfgrass areas where optimum seedbed preparation or cultivation cannot be accomplished. Overseeding strengthens or reestablishes turfgrass stands in small bare areas, increases the density of established turf, or infuses new varieties or different types of grasses into established turfgrass stands. The overseeding rates in Tables 7–10 are standard recommendations; individual site characteristics such as soil type, time of year, and cultural practices may affect these numbers slightly.

Roadside and Slope Stabilization

Grasses or grass and legume mixtures are widely used to establish vegetation along roadsides and stabilize erodible slopes; see Table 11 for common types of grasses that work well for this purpose. Wheatgrasses have excellent seedling vigor and compete well against weeds east of the Cascades. If irrigation will not be provided, plant wheatgrasses in early spring or as a late fall dormant seeding.

Table 8. Overseeding recommendations for golf course fairways.

GrassSeeding rate(percentage by weight)*Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Perennial ryegrass50NR**R***
  -plus
    Kentucky
    bluegrass
50NRR
Perennial ryegrass80RR
  -plus colonial
    bentgrass
20RR
*Overseeding rates can vary from 75 to over 400 lb/acre. Contact your local Extension specialist for more information.
**Not recommended.
***Recommended.

Table 9. Overseeding recommendations for home lawns, parks, and cemeteries.

GrassSeeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Perennial ryegrass6R*R
Perennial ryegrass4RR
  -plus creeping red,
    Chewings, or hard
    fescue
2RR
Creeping red, Chewings, or hard fescue2RNR**
  -plus colonial bentgrass0.5RNR
Kentucky bluegrass (blended varieties)2NRR
Kentucky bluegrass (blended varieties)1NRR
  -plus creeping red,
    Chewings, or hard
    fescue
2NRR
Perennial ryegrass4NRR
  -plus Kentucky
    bluegrass
1.5NRR
Tall fescue6–8limited useR
*Recommended.
**Not recommended.

Table 10. Overseeding recommendations for athletic fields.

GrassSeeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Perennial ryegrass6R*R
Perennial ryegrass4RR
  -plus Kentucky
    bluegrass**
1.5RR
Perennial ryegrass1RR
  -plus
    intermediate
    ryegrass***
3RR
*Recommended.
**Kentucky bluegrass seedlings are extremely poor competitors during establishment. If turfgrasses cover as much as 50% of the ground, seed turf-type perennial ryegrasses alone since Kentucky bluegrasses will not compete favorably.
***Use intermediate ryegrass very early or late during the seasons when soil temperatures are too cool to get quick cover by perennial ryegrass or Kentucky bluegrass. Intermediate ryegrass will act as a biennial in most cases.

Table 11. Seeding recommendations for roadside and slope stabilization*.

GrassSeeding rate(lb/1,000 ft2)Western Washington and Western OregonIdaho, Eastern Washington, and Eastern Oregon
Crested wheatgrass**0.5–1.0NR***R****
Streambank wheatgrass**1NRR
Hard fescue*****1NRR
Hard fescue0.35NRR
  -plus crested wheatgrasse0.5NRR
Sheep or Idaho fescue*****1NRR
Common or improved perennial ryegrass1.5RR
  -plus creeping red or Chewings
    fescue
1RNR
Common or improved perennial ryegrass1.5RNR
  -plus creeping red or Chewings
    fescue
1RNR
  -plus white Dutch clover0.1RNR
Colonial bentgrass can be added to the two preceding entries for wet sites0.25RNR
*These rates are based upon prepared seedbeds seeded with a brillion drill or hydroseeding methods.
**On nonirrigated 8–15 inch rainfall areas, crested wheatgrass and streambank wheatgrass perform very well.
***Not recommended.
****Recommended.
*****On nonirrigated 15–25 inch rainfall areas, sheep, hard, or Idaho fescue and crested wheatgrass perform well.

Authors: G.K. Stahnke, Associate Extension Agronomist, and E.D. Miltner, Associate Research Agronomist, Washington State University, Puyallup; R.C. Golembiewski, Assistant Professor of Horticulture, Oregon State University, Corvallis; T.A. Salaiz, Turfgrass Extension Specialist, University of Idaho, Aberdeen; and W.J. Johnston, Professor of Crop Science, WSU, Pullman.

Websites with the most recent bentgrass variety rankings

Washington State University: http://turf.wsu.edu/; http://www.puyallup.wsu.edu/turf

Oregon State University: http://www.BeaverTurf.com

University of Idaho: http://www.extension.uidaho.edu/idahogardens/

National Turfgrass Evaluation Program: http://www.ntep.org

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PNW299