Alfalfa planted in August establishes well when moisture is available. Be sure to plant early enough so alfalfa has 6 to 8 weeks between emergence and freeze back to develop good cold tolerance. That means that if you are in northern Nebraska or southern South Dakota, you need to plant in early August. But only if you also have moisture right away for seeds to germinate. Any delay is likely to cause poorer stands. In southern Nebraska you can plant a little later, mid-August is ideal while planting after August 31st becomes risky. In central Kansas alfalfa can be planted as late as mid-September.
Seedbed preparation is crucial for late summer plantings. Good seed-to-soil contact and weed control are critical, both when seeding into prepared seedbeds or into wheat stubble. Conserve soil moisture whenever possible, and put extra effort into getting a firm seedbed.
Whenever seeding alfalfa in August, be especially wary of grasshoppers. They sometimes seem to come from nowhere, and they love to eat new seedlings. Spray field margins with insecticides before planting if necessary.
One important caution -- never plant into dry soil. August plantings into dry soil may lie dormant for several weeks. Too little time remains for seedlings to develop good cold tolerance. Many failures occurred in recent years because folks forgot that fall rains are unreliable.
But if you have moisture, then plant. With help from Mother Nature, good hay is just a spring away.