When To Plant Alfalfa In Oklahoma

Knowing when to plant alfalfa in Oklahoma is the single most important decision you’ll make for a successful stand. Get the timing right, and you set the stage for high yields and a perennial crop that lasts for years. Get it wrong, and you might face poor germination, weak seedlings, or winterkill. This guide cuts through the confusion to give you the clear, practical advice you need for optimal results in our state.

For most of Oklahoma, the answer is straightforward: late summer to early fall. This is often called “dormant seeding.” Planting during this window gives seedlings the best chance to develop a strong root system before winter dormancy, leading to vigorous growth the following spring. Let’s break down why this timing works so well.

Why Fall Planting is the Winner

Fall planting aligns perfectly with Oklahoma’s climate patterns. The intense summer heat has passed, but the soil is still warm from months of sun. This warm soil encourages excellent seed germination. At the same time, cooler air temperatures reduce stress on the delicate young seedlings.

Most importantly, fall rains (hopefully!) provide the moisture needed for establishment. The goal is for plants to grow for 6-10 weeks before the first hard freeze. In this period, they develop a robust crown and taproot that stores energy for winter. Come spring, these established plants explode with growth, often yielding a good first cutting earlier than spring-planted fields.

The Risks of Spring Planting

Spring planting in March or early April is possible, but it comes with significant challenges. The primary enemy is weeds. Alfalfa seedlings are slow starters, and they struggle to compete with fast-growing spring weeds. This often requires more intensive herbicide management.

Spring also brings unpredictable rainfall. A dry period after planting can doom the crop. Furthermore, spring-planted alfalfa won’t have the deep root system to handle Oklahoma’s summer drought stress. It’s yields in the first year are typically lower. For these reasons, spring planting is generally recommended only in the state’s panhandle or if you missed the fall window and have good irrigation.

Regional Timing Variations Across Oklahoma

Oklahoma’s diverse geography means your ideal dates shifts a bit. Here’s a quick regional guide:

Northern Oklahoma: Aim for August 20 to September 10. Earlier is better to ensure enough growth before frost.
Central Oklahoma: The prime window is September 1 to September 20. This includes areas around Oklahoma City.
Southern Oklahoma: You can plant a bit later, from September 10 to October 1. The warmer fall extends the growing period.
Panhandle: Here, both early spring (April) and late summer (August 15-31) are viable options due to the cooler climate.

Step-by-Step Pre-Planting Checklist

Timing is useless without proper preparation. Follow these steps in the months before your target planting date.

Soil Test: This is non-negotiable. Alfalfa requires well-drained soil with a pH between 6.5 and 7.5. Test at least 3 months ahead to allow time to amend the soil.
Address Soil pH: If your pH is low, apply lime according to test recommendations. It takes months for lime to fully react with the soil.
Fertilize for Phosphorus & Potassium: Based on your soil test, apply these nutrients before planting. They are crucial for root development and winter hardiness.
Choose the Right Variety: Select a variety with proven disease resistance and winter hardiness for Oklahoma. Your county extension agent can provide the best current recommendations.
Control Perennial Weeds: Use a non-selective herbicide or tillage the season before planting to eliminate tough weeds like bermudagrass or johnsongrass.

Planting Day: Techniques for Success

When your date arrives, focus on these key practices to ensure a good stand.

Seedbed Preparation: Create a firm, fine seedbed. The classic test is that your boot heel should sink no more than half an inch when you step on it. This prevents seeds from being planted to deep.
Seeding Depth: This is a common mistake. Plant alfalfa seeds no deeper than ¼ to ½ inch in heavy soils, and no more than ¾ inch in sandy soils. Too deep, and seedlings won’t emerge.
Seeding Rate: For a pure stand, aim for 15 to 20 pounds of pure live seed (PLS) per acre. Using inoculated seed specific to alfalfa is highly recommended to ensure proper nitrogen fixation.
Post-Planting Rolling: If possible, use a light roller after planting. This ensures good seed-to-soil contact, which is vital for moisture uptake and germination.

First-Year Management After Planting

Your job isn’t done after seeding. Care in the first year ensures longevity.

Fall Growth: Allow seedlings to grow without grazing or cutting in the fall. Let them reach about 6-8 inches tall before a killing frost. This builds root reserves. Avoid the temptation to take a hay cutting; it severely weakens the plants.

Weed Scouting: Monitor for weed pressure. Some broadleaf weeds may require a post-emergent herbicide, but be sure it’s safe for young alfalfa. Always read the label carefully.

First Spring Harvest: For fall-planted alfalfa, wait until the plants are in the late bud to early bloom stage for your first cutting the following spring. This allows the stand to fully mature and maximizes root carbohydrate stores.

Common Mistakes to Avoid

Steer clear of these pitfalls that can ruin a new alfalfa field.

Planting into a weedy or poorly prepared seedbed.
Ignoring soil pH and fertility recommendations from a test.
Planting to deep, which is the number one cause of seeding failure.
Harvesting or grazing the new seeding in the fall of the planting year.
Choosing a variety based on price alone, without considering disease resistance.

FAQ: Your Oklahoma Alfalfa Questions Answered

Can I plant alfalfa in the spring in Oklahoma?

You can, but it’s riskier than fall planting. Spring planting faces more weed competition and summer drought stress. It’s best suited for irrigated fields or if fall conditions prevented planting.

What is the latest date to plant alfalfa in Oklahoma?

For central OK, aim to have seed in the ground by late September. In southern areas, you might push into early October. The rule is to allow a minimum of 6 weeks of growth before a hard freeze (temps below 25°F).

How do I prepare an old field for alfalfa?

Start with a soil test. Control existing vegetation with glyphosate. Consider a “stale seedbed” technique: prepare the bed early, let weeds germinate, and kill them just before planting your alfalfa. This reduces weed pressure alot.

Should I use a cover crop with alfalfa?

It’s generally not recommended for Oklahoma. A companion crop like oats can compete to aggressively for water and nutrients, often leading to alfalfa stand failure. The best practice is to plant alfalfa alone into a clean seedbed.

How long does an alfalfa stand last in Oklahoma?

With good management, including proper cutting height and soil fertility, you can expect a productive stand to last 4 to 7 years. Thinning often occurs after the third or fourth year, at which point you may need to consider renovation or rotation.

Getting your alfalfa off to a strong start hinges on correct timing and careful preparation. By targeting that late summer to early fall window, you work with Oklahoma’s climate rather than against it. Remember to test your soil, plant shallow, and protect those young seedlings in their first year. Following these steps will give you a resilient, high-yielding stand that provides quality forage for seasons to come.