Free Guide to Planting Alfalfa for Growers

Understanding Alfalfa and Its Growing Requirements

Alfalfa is a perennial legume crop that has been grown in the United States for over 300 years. According to the U.S. Department of Agriculture, alfalfa occupies approximately 8.5 million acres across the country and serves as a critical feed source for livestock operations. The crop gets its name from the Arabic word "al-fal-fa," meaning "father of all foods," which reflects its high nutritional value for cattle, horses, sheep, and other animals.

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The plant grows from 1 to 3 feet tall with deep root systems that can extend 10 to 20 feet into the soil, depending on conditions. This deep rooting characteristic makes alfalfa particularly valuable because it can access water and nutrients unavailable to shallower-rooted crops. The plant produces small purple, pink, yellow, or blue flowers that develop into seed pods containing multiple seeds.

Alfalfa thrives in well-drained soils and requires full sun—at least 6 to 8 hours of direct sunlight daily. The crop performs best in slightly alkaline to neutral soils with a pH between 6.5 and 8.0. Soil testing before planting provides valuable information about pH levels, nutrient content, and organic matter. Most state university extension offices offer soil testing services at minimal cost, typically ranging from $10 to $25 per sample.

The crop can be grown in most regions of the United States, though it performs particularly well in the western states, upper Midwest, and parts of the Northeast. Alfalfa requires moderate moisture during establishment but becomes quite drought-tolerant once established due to its deep root system. The plant grows during spring and early summer, goes dormant in winter, and can produce multiple harvests annually depending on climate and management practices.

Practical Takeaway: Before investing in alfalfa planting, conduct a soil test through your local extension office to understand your soil's pH level, nutrient status, and drainage characteristics. This information directly impacts variety selection and planting success.

Selecting the Right Alfalfa Variety for Your Region

Alfalfa varieties differ significantly based on their adaptation to specific climates and growing conditions. The University of Wisconsin Extension notes that variety selection represents one of the most important decisions a grower makes, as it affects yield, quality, winter survival, and disease resistance. Modern alfalfa varieties have been bred to perform well in particular regions, and choosing a non-adapted variety can result in poor establishment, reduced yields, or winterkill in cold climates.

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Varieties are broadly categorized by dormancy class, which indicates how the plant responds to winter day length and temperature changes. Non-dormant varieties (Class 0) grow vigorously year-round in mild climates but struggle in regions with harsh winters. Semi-dormant varieties (Classes 3-7) stop growing in fall but resume in spring, making them suitable for transition zones. Dormant varieties (Classes 8-10) shut down completely in autumn and survive extreme winter conditions, making them appropriate for northern growing regions.

For northern states like Minnesota, Wisconsin, and North Dakota, dormant or semi-dormant varieties provide the best winter survival rates. Examples include varieties bred for these regions by university programs and seed companies specializing in northern agriculture. In the western states and California, non-dormant and semi-dormant varieties often produce more harvests annually because growing seasons are longer. Southern growing regions typically use non-dormant varieties that can withstand heat and humidity.

Modern varieties also incorporate disease resistance traits. Some resist Verticillium wilt, Phytophthora root rot, and various bacterial and fungal diseases. Seed tags and variety descriptions from seed suppliers indicate which diseases a variety resists. Growers should prioritize disease resistance in regions where particular diseases are known problems. Working with university extension specialists in your state helps identify varieties with proven performance records in your specific location.

Seed costs vary based on variety and purity level. Quality seed typically costs between $1.00 and $3.00 per pound, though premium varieties with enhanced disease resistance may cost more. A standard seeding rate is 15 to 20 pounds per acre, so seed costs typically range from $15 to $60 per acre before any herbicide or inoculant treatments.

Practical Takeaway: Contact your state's university extension office and request variety recommendations specific to your county or region. Ask extension specialists which varieties show strong performance records in your exact climate zone and soil type.

Soil Preparation and Testing Before Planting

Successful alfalfa establishment depends heavily on soil preparation. The crop is sensitive to soil conditions during its first year, when seedlings are small and compete with weeds and residual vegetation. Unlike annual crops, alfalfa occupies the same field for 4 to 8 years, so investing time in proper soil preparation pays returns throughout the crop's lifespan.

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Soil testing should occur at least 6 to 12 months before planting, allowing time to make amendments if needed. Testing reveals pH level, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and organic matter content. Alfalfa requires higher levels of phosphorus and potassium than many crops—typical recommendations are 30 to 50 pounds of P₂O₅ per acre and 100 to 150 pounds of K₂O per acre, depending on soil test results.

If soil pH falls below 6.5, lime application may be necessary. Lime takes months to fully react in soil, which is why testing in advance matters. Application rates vary based on soil type and current pH but typically range from 1 to 3 tons per acre. Growers should follow lime recommendations from their soil test report rather than guessing at rates.

Field preparation typically involves removing existing vegetation or crop residue through tillage or herbicide treatment. Fields should be relatively free of perennial weeds like quackgrass, bindweed, and wild onion because these compete aggressively with young alfalfa seedlings. Multiple tillage operations or targeted herbicide applications in the weeks before planting help reduce weed seed germination. Organic growers may use mechanical methods like cultivation and flame weeding.

Creating a fine seedbed helps alfalfa seeds make good contact with soil moisture. Seeds are very small—approximately 200,000 to 250,000 seeds per pound—so they must be placed in close contact with moist soil to germinate. Fields with large clods or excessive surface residue result in poor seed-to-soil contact and stand establishment failure.

Practical Takeaway: Submit soil samples to your extension office 8 to 12 months before planting. If amendments are needed, apply them and allow time for incorporation. Two to three weeks before planting, work the field to create a smooth seedbed free of large clods and debris.

Planting Methods, Timing, and Seeding Rates

Alfalfa can be planted in spring or fall, depending on your region's climate. In northern states, spring planting (late April through May) is preferred because it allows seedlings to establish before winter stress. Fall planting works in southern regions where mild winters allow continued establishment. Regardless of timing, avoid planting during extremely hot, dry periods when seedlings struggle to emerge and establish.

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Several planting methods are available to growers. The most common approach uses a grain drill with alfalfa boxes or a broadcast spreader followed by light incorporation. No-till seeding into killed sod is another option for growers managing erosion or avoiding excessive tillage. Grass-legume mixture plantings combine alfalfa with timothy, orchardgrass, or other grasses, creating higher-quality hay for livestock. The specific method depends on farm equipment, current field conditions, and grower preference.

Standard seeding rates are 15 to 20 pounds of pure live seed (PLS) per acre. PLS accounts for seed purity and germination percentage—both shown on seed labels. For example, seed with 90% purity and 85% germination has 76.5% viability, so you must increase the seeding rate accordingly to achieve the desired PLS per acre. Seed suppliers and extension educators can calculate the exact seeding rate needed from label information.

Seeding depth matters significantly. Alfalfa should be planted at depths of one-quarter inch to one-half