Kentucky Bluegrass Seed Production

Introduction

Kentucky bluegrass is a cool-season, sod-forming perennial grass. Cultivars range from short to medium height one to three inches (2 to 8 cm). Kentucky bluegrass is adapted to a wide range of mineral and organic soils. However, it is most productive on fertile well-drained soils with a pH greater than five. It grows best in humid areas at air temperatures between 15 and 32°C and is one of our most cold-hardy grasses.

The climate and soils in Manitoba are well adapted to the production of Kentucky bluegrass. Growers report yields of 300 to 600 lbs/acres (350 to 675 kg/ha). The major market for this seed is the lawn grass industry. The price fluctuates in response to the general economy and the amount of activity in the housing industry. Growers should contact the various members of the Canadian seed trade for the current price being paid for Kentucky bluegrass seed.

Plant Development

Seedlings develop slowly but produce many tillers which must reach a certain size or stage of growth by fall. At that time they react with the shorter days and cooler temperatures to grow flowers. Less well-developed tillers cannot respond to the light-temperature stimulus and never produce flower heads. Good seed yields require adequate fall growth, often coupled with thinning of stands, to reduce excess competition among tillers. For seed production management, practices must be directed toward producing healthy, large tillers before the fall seed induction period.

Site Selection

The field chosen for seed production should be free of quackgrass, other perennial weeds and impediments such as stones which interfere with tillage, seeding and harvest. In Manitoba, seed yields are highest on clay or loam soils. Annual precipitation of 20 inches (50 cm) is considered adequate for production of forage or seed.

The bluegrasses are apomictic; this means they produce seed without fertilization. Consequently, for the production of certified seed, isolation distances from other bluegrasses is only 17 feet (five metres).

Site Preparation

The selected site should be fallowed the year before the stand is established. The tillage operation may be preceded by an application of Roundup to control quackgrass and other serious perennial weeds. Fallowing will also ensure the preparation of a fine, firm seedbed.

A soil test should be taken in the fall to determine the status of soil nutrients. Just before seeding, the field should be fertilized according to soil test recommendation, then worked lightly and packed.

Seeding

Seeding in spring is generally best because temperature and moisture conditions are usually ideal for germination and emergence. Spring seedlings have a long period to develop tillers before the critical fall temperature/light induction period. Stands can be established through late spring and summer up to late August, but fewer tillers will be induced to produce seed heads the following year.

The seed should be placed no deeper than 1/4 inch(6 mm). Seeding in 12 inch(30 cm) rows is recommended if moisture is adequate; wider spacings may be used in drier conditions.

The rate of seeding will vary with seedbed preparation, the time of seeding and the cultivar. Usually, the range is from one to four lb/acre (one to four kg/ha). The lower rates are used on fertile, moist, well-prepared seedbeds and/or for cultivars which tiller profusely.

Kentucky bluegrass is preferably seeded without a companion crop since these crops are too competitive and impede tiller development. If a companion crop must be used, choose one such as flax which offers relatively less competition. Seeding rates for the companion crop should be reduced by one third to one half of the normal seeding rate.

Harvesting

Bluegrass cultivars flower early and their seed is usually ripe by mid-July. The seed is ready to harvest when the seed heads have turned brown. Bluegrass does not shatter readily, so the best method for harvesting is swathing followed by combining. It is difficult to separate the seed from the straw; consequently, if the conventional combine is used, it may be necessary to pass the seed through the combine twice to have a product which can be augered and stored conventionally. The new rotary or axial flow combines work extremely well with bluegrass and usually make a second pass through the machine unnecessary.

Burning

It is essential that Kentucky bluegrass seed fields be burned. This not only provides sanitation for the field, but also stimulates seed production for next year. Studies conducted in Minnesota have indicated up to a six-fold increase in seed production from fields burned after harvest compared to unburned fields. The best time to burn is immediately after combining the seed crop. A good chopper and spreader on the combine is an advantage to avoiding a concentration or hot spot when burning.

Weed Control

Avenge can be used to control wild oat when Kentucky bluegrass is underseeded to a companion crop. Lontrel can be used to control some perennial and annual broadleaf weeds. Consult Manitoba Agriculture, Food and Rural Initiatives Guide to Crop Protection for more complete information.