August Best Time To Seed Grasses

Seeding grasses as early as possible during August in the Midwest will produce the best results for next year’s yields, reports Dan Undersander, University of Wisconsin forage agronomist.

Undersander reports they seeded six forage grasses at several late-summer and fall dates at three sites in Wisconsin (River Falls, Arlington and Lancaster) over three years. Seeding dates were spaced approximately every two to three weeks from about Aug. 1 to late November.

Species included orchardgrass, smooth bromegrass, timothy, reed canarygrass, perennial ryegrass and tall fescue. All of the grasses seeded by mid- to late September produced stands with visible plants before a killing frost most years, and these plants usually survived the winter. Later seedings did not produce visible plants until spring, if at all.

Slow-establishing species, particularly reed canarygrass, produced better stands when seeded by early September. Timothy tended to be the most variable with regard to seeding date and next-year yield. In only one trial out of nine did a November seeding, where the seed lay dormant over winter, produce a stand the next spring.

The most important finding is that grasses with earlier seeding dates (early through mid-August) usually had more tillers per square foot, more tillers per plant and higher dry matter yield the following season. The average first-cutting yield the spring after seeding ranged from 1.5 tons/acre to less than 0.5 ton/acre when the grasses were harvested at the boot stage, depending on when they were sown the previous year. By later cuttings the stands had recovered and all yielded well.

However, delaying late-summer seeding from mid-August to mid-September generally resulted in 1 ton/acre less yield the next year. Undersander says this study clearly shows that delaying grass seeding in the late summer or early fall not only increases the risk of establishment failure but reduces yield of the stand the next year.