When To Plant Alfalfa In Missouri

If you’re a Missouri farmer or a dedicated gardener looking to establish a perennial forage, knowing when to plant alfalfa in Missouri is the most critical step for success. Getting the timing right sets the stage for a strong stand that can yield for several years, making it a vital piece of your planning.

Spring and fall are both viable planting windows in our state, but each has its own set of advantages and risks. The best choice for your field depends heavily on your specific location, soil conditions, and that year’s weather patterns. Let’s break down the optimal timing so you can make a confident decision.

Missouri’s climate, with its hot summers and variable winters, creates two primary planting seasons: spring and late summer to early fall. The goal is to seed when soil moisture is good, temperatures are moderate, and the young seedlings have enough time to develop a robust root system before extreme weather hits.

Spring Planting: The Traditional Window

Spring planting is common and often preferred in northern Missouri or on fields where fall planting is risky. The key is to wait for the soil to be ready.

Optimal Timing: Aim for mid-April to mid-May. Soil temperature at seeding depth should be at least 50°F and rising.
Advantages: You have the whole growing season ahead. Spring rains usually provide good moisture. It allows for a harvest or two in the establishment year.
Risks: Competition from weeds is typically higher in spring. A late frost can damage seedlings. Dry spells in early summer can stress young plants before their roots are deep.

For spring success, focus on soil preparation the previous fall. A well-drained seedbed is non-negotiable. Make sure to test your soil pH and fertility early; alfalfa requires a pH of 6.5 or higher for optimal growth.

Fall Planting: The Preferred Method for Many

Fall planting, often called “dormant seeding,” is highly recommended for central and southern Missouri. It takes advantage of cooler temps and fall moisture.

Optimal Timing: Target August 15 to September 10. This is critical—seedlings need a minimum of 6-8 weeks of growth before the first killing frost.
Advantages: Weed competition is usually much lower. Cooler temperatures reduce moisture stress. Plants establish roots in the fall and are ready to explode in growth the following spring, often yielding more in the first full year.
Risks: A dry August can delay planting or hinder germination. An early, hard freeze can kill vulnerable seedlings. It does not allow for a harvest in the seeding year.

The fall window is tighter than spring’s. Don’t gamble with a late planting; if you miss the deadline, it’s safer to wait for spring.

Regional Considerations Across Missouri

Missouri’s long north-south gradient means timing shifts a bit by region.

Northern Missouri: Spring planting (April-May) is very reliable. Fall planting is possible but riskier; aim for the very early part of the window, by September 1st.
Central Missouri: Both seasons work well. Fall planting (Aug 20 – Sept 5) is often the top choice for its vigor and yield potential.
Southern Missouri: Fall planting (Aug 15 – Sept 1) is generally best. Springs can be wet, delaying fieldwork, and summer heat arrives quickly, stressing spring seedlings.

Step-by-Step Guide to Planting Alfalfa

Once you’ve chosen your season, proper execution is everything. Follow these steps.

Soil Test and Amend: Take a soil test 6-12 months ahead. Apply lime if needed to raise pH to 6.5-7.0; this takes time. Address phosphorus and potassium deficiencies based on the report.
Prepare a Firm Seedbed: Create a firm, fine, and weed-free seedbed. The old rule is that your footprint should not sink more than half an inch. This ensures good seed-to-soil contact.
Select the Right Seed: Choose a variety with proven disease resistance (like Phytophthora and Anthracnose) and winter hardiness suited for Missouri. Don’t skimp on seed quality.
Plant at the Correct Depth: This is a common mistake. Alfalfa seed is tiny. Plant at ¼ to ½ inch deep in heavy soils, and no more than ¾ inch in sandy soils. A drill with press wheels is ideal.
Use the Proper Seeding Rate: For a pure stand, aim for 15-20 pounds of live seed per acre. If using a nurse crop (like oats in spring), reduce the rate slightly. Higher rates don’t compensate for poor bed preparation.
Manage Weeds and Pests: Scout fields regularly. Use pre-emergent herbicides if needed, and control insects like potato leafhoppers, which can devastate new seedlings.

Critical Mistakes to Avoid

Even with good timing, these errors can ruin a stand.

Planting in Wet Soil: Working soil when it’s too wet creates clods and compaction, leading to poor emergence. Patience is key.
Incorrect Seeding Depth: Planting too deep is the number one cause of seeding failure. When in doubt, err on the shallow side.
Poor Weed Control: Weeds steal light, water, and nutrients. Have a management plan ready before you plant.
Harvesting Too Soon: In the establishment year, wait until the plants are in full bloom for the first cutting. This allows the root system to build up reserves.

Another frequent oversight is not inoculating the seed with the proper rhizobium bacteria (for nitrogen fixation). Always use a fresh, specific alfalfa inoculant.

FAQs: Planting Alfalfa in Missouri

Can I plant alfalfa in the summer in Missouri?

Summer planting (June-July) is generally not recommended. The heat and drought stress make it extremely difficult for seedlings to survive without intensive irrigation. It’s a high-risk endeavor.

What is the best month to plant alfalfa in Missouri?

There isn’t one single “best” month. For spring, April is often ideal. For fall, late August is the prime target. Your specific location and that year’s weather are the final deciders.

How late is too late to plant alfalfa in the fall?

If seedlings won’t have at least 6 weeks of growth before a killing frost (24°F), it’s too late. For most of Missouri, planting after September 10-15 becomes very risky. A better stand will result from waiting for spring.

Can I frost seed alfalfa in Missouri?

Frost seeding (broadcasting seed on frozen ground in late winter) is unreliable for alfalfa. Alfalfa requires good soil contact and precise depth control. It’s a technique better suited to clovers in pastures, not for establishing a pure alfalfa hay field.

Should I use a nurse crop when planting alfalfa in the spring?

A nurse crop like oats can help control erosion and suppress some weeds. However, it also competes fiercely for water and light. In Missouri, it’s often better to plant alfalfa alone in a well-prepared seedbed and manage weeds with other methods. If you do use one, make sure to harvest or remove it early.

Choosing when to plant alfalfa in Missouri is a balance of science, observation, and sometimes a bit of luck with the weather. By understanding the strengths of both spring and fall windows, preparing your site meticulously, and avoiding common pitfalls, you can establish a thick, productive stand. Pay close attention to your soil test, the calendar, and the forcast, and you’ll give your alfalfa the best possible start for years of reliable production.