Establishing an alfalfa stand is typically done in the spring, but it can also be accomplished in late summer in NW Iowa. This procedure can be advantageous with crop rotations involving small grains or when a spring seeded alfalfa stand did not establish very well. Late summer seeded alfalfa should only be attempted when conditions allow for it.

Having a good, firm seedbed and plentiful moisture are essentials for a successful seeding operation, whether it is late summer or spring. Seeding should begin by early August and be completed by mid to late August. The seedlings need a minimum of six weeks to develop a root system (before the first hard frost) that will sustain the plant through the winter. The first hard freeze (26 F) in northwest IA typically occurs in late September to early October.

Herbicides and companion crops are typically not necessary when establishing a new seeding in late summer. A companion crop of rye or wheat most often becomes too competitive to the alfalfa. As with traditional spring seeded of alfalfa, a firm, moist seedbed is extremely important. A seeding rate of 12 to 15 lbs. of seed/acre should be used. Stands established in late summer often produce near full production the following year (assuming good winter survival).

You may have attempted to establish an alfalfa field last spring and did not have the success that you had hoped for. A newly seeded stand should have approximately 20 plants per square foot going into the winter months. Over-seeding into the existing thin stand can be an option as long as the original alfalfa stand is less than 12 months old. Older alfalfa stands tend to have auto-toxicity problems, which result in reduced germination, viability and yield of the newly seeded alfalfa. A no-till drill should be used for proper seed placement. If weeds are present, herbicides or clipping should be employed to reduce competition. Once again, a firm, moist seedbed is critical to successfully over-seed alfalfa into an existing alfalfa field.

Before attempting to improve a new alfalfa seeding, try to determine what the original problem was. Consider the following items when determining what may have led to the failure of the original stand.

• What is the soil pH? It should be no lower than 6.5.
• What condition was the seedbed in? Was there good seed to soil contact and good soil moisture?
• Planting depth should have been a uniform ¼ to ½ inches deep.
• Was there herbicide carryover from the previous cropping year. Check last year’s herbicide program rotational restrictions with alfalfa.

Late summer seeded alfalfa can be successfully accomplished if you follow the steadfast rules of developing a good firm seedbed; make sure there is good moisture throughout the soil profile and allow ample time after seeding for the seedling root systems to develop.

Todd Vagts
Iowa State University Extension
Field Crops Specialist
1240 D. Heires Avenue 
Carroll, IA 51401 
Office: 712-792-2364; Cell: 712-249-6025;  Fax: 712-792-2366
Email: vagts@iastate.edu  

For questions or comments please respond to vagts@iastate.edu

This page last updated on 07/21/03