Grass Seed

 Willamette Valley Grass Seed Production

Oregon is the world’s major producer of cool-season forage and turf grass seed and a widely recognized center of expertise in seed production. Most of the acreage is located in the Willamette Valley, the “grass seed capital of the world.” Farm gate value of Oregon’s production for the last several years has been historically low. Farm gate sales for 2010 were estimated to be $228,464,000. Collectively, Oregon’s Willamette Valley produces almost two-thirds of the total production of cool-season grasses in the United States (U.S.).

Grass seed is produced on nearly 1,500 grass seed farms in Oregon. Seed production of one or more grass species are the major enterprises, with growers using machine technology especially adapted to small seeds. Mild and moist winters with dry summers favoring seed development and harvest make the Valley an ideal place to produce high quality seed. Over 390 seed conditioning plants located in the Willamette Valley prepare the seed for market once the harvest operation is complete.

Prior to World War II, farms in the Willamette Valley were more diversified and smaller than farms today. Grass seed was introduced as early as the 1920s as an alternative crop for the south valley. Ryegrass was especially well adapted to the wet soils and soon became an important crop. Grass seed also established itself as an excellent alternative crop for the highly erodible foothill soils found on the valley’s eastern flank. Since 1940, the industry has made steady growth, with many national and international seed companies located in the Willamette Valley.

The Willamette Valley’s mild, wet winters and dry summers have provided an ideal environment for the grass seed industry to expand. Grass seed crops are grown on more than half of the total harvested cropland in the Willamette Valley. In 2010, Oregon growers produced over 592 million pounds of cool-season grass seed crops. Today, seed crops of over 950 varieties from eight grass species are grown on over 375,000 acres statewide. Of these, 347, 000 acres are located in the Willamette Valley.

Oregon growers produce essentially all of the U.S. production of annual ryegrass (Lolium multiflorum Lam.), perennial ryegrass (L. perenne L.), bentgrass (Agrostis spp.), and fine fescue (Festuca spp.). Smaller amounts, but significant portions of the USA production of Kentucky bluegrass (Poa pratensis L.), orchardgrass (Dactylis glomerata L.), and tall fescue (Festuca arundinacea Schreb.) are also grown in Oregon.

For more information on grass seed produced in Oregon and the Willamette Valley:

Seed Production Research Reports

Oregon Seed Council

Publication: Using Seed Moisture as a Harvest Management Tool

Video: Using Seed Moisture as a Harvest Management Tool

Grass Seed Nutrient Management

Nutrient Management in Grass Seed Crops

Before planting a grass seed crop, test soil for pH, phosphorus, potassium, calcium, magnesium, and lime requirement. Add and incorporate material before planting.

Nitrogen is needed by all grass seed crops. A small amount, of fall nitrogen is recommended for tall fescue. For perennial ryegrass, fall nitrogen is not required. A small mount of fall nitrogen, 30 to 40 lb/a, and can be applied and used to reduce spring nitrogen rate.

Most of the N is supplied in the spring from mid-February to mid-April in two to three applications or “splits”. Nitrogen application rate varies for grass species. Fine fescue requires the lowest rate, 30 to 70 lb/a and perennial ryegrass the highest, 120 to 160 lb/a. Refer to fertilizer and nutrient management guides for each grass species for specific nitrogen rate information.  

Straw removal by baling removes a substantial amount of potassium. Monitor soil test potassium where straw is baled.  More information on nutrient amounts and value in grass straw.


Click on the following links to view related OSU Extension Publications:

Applying Lime to Raise Soil pH for Crop Production (Western Oregon), EM 9057

Soil Acidity in Oregon: Understanding and Using Concepts for Crop Production, EM 9061

Postharvest Residue Management for Grass Seed Production in Western Oregon

Nutrient Management for Annual Ryegrass Grown for Seed

Fertilizer Guide: Tall Fescue Grown for Seed

Fertilizer Guide: Orchardgrass Grown for Seed

Fertilizer Guide: Fine Fescue Grown for Seed

Perennial Ryegrass Grown for Seed (Western Oregon)

Soil Test Interpretation Guide

Monitoring Soil Nutrients Using a Management Unit Approach

Nutrient Amounts and Value in Grass Straw

Grass Seed Weed Management


The OSU Weed Science Group conducts greenhouse, laboratory and small plot herbicide evaluation trials in support of the development of weed management activities in the diverse cropping systems of Western Oregon.  Labeled and experimental herbicides are evaluated for crop safety and weed control efficacy in the following crops:  Winter and Spring Wheat, Cool-season Grasses grown for seed, Native cool-season Grasses and forbs grown for seed, Canola, Meadowfoam, Camelina, Clovers and Peppermint among others.

Annual Bluegrass

Roughstalk Bluegrass

Rattail Fescue

California Brome

Sharp Point Fluvelin

Annual Sowthistle

Mayweed Chamomile

Catchweed Bedstraw

Prickly Lettuce

Weed Science Related Links:

Weeds of the West

Weeds of California and Other Western States 

PNW Weed Management Handbook 

PNW Weed Management Extension Publications Series

Postharvest Residue Management for Grass Seed Production in Western Oregon

Oregon Society of Weed Science

Western Society of Weed Science



Weed Identification Resources:

Weed Science Society of America

Center for Invasive Plant Management

USDA Plants Database


Herbicide Labels:

CDMS Database

Grass Seed Disease/Insect Management

Grass Seed Diseases

 Stem Rust

USDA Stem Rust Model

Stripe Rust


Stripe Smut

Rynchosporium Scald

Blind Seed


Rathay's Disease

Brown Stripe


Grass Seed Insects

Orchardgrass Billbug


European Crane Fly

 Sod Webworm

 Garden Symphylan

Grey Garden Slug

 Winter Grain Mite

 Wireworm/Click Beetle

 March Fly

Grass Thrips

Meadow Plant Bug

 Army Worm