How to Plant, Grow, and Care for Alfalfa

Alfalfa (also called lucerne) may not be the most exciting crop to grow, but it is highly reliable. Alfalfa is in demand around the world as a feeder crop, and due to its fast growth rates and high yield, it can be a solid money-maker. Further, alfalfa also contributes vital nutrients back into the soil, including nitrogen, making it an excellent option for crop rotation as well.

Raising alfalfa is relatively easy, but still has its own challenges. Read on for our comprehensive guide to planting and growing alfalfa and maximizing harvests.

Alfalfa Basics

Soil Requirements and Preparation

Alfalfa is not very picky about soil but grows best in deep well-drained loamy soil with a pH around 7. It does need deep soil — at least three feet to grow effectively.

Perform a soil test before planting alfalfa and be prepared to fertilize as needed. As a legume, alfalfa can fix its own nitrogen (N), so consider planting it in nitrogen-starved fields, as it will contribute nitrogen back to the soil. Otherwise, optimal fertilization for alfalfa is approximately 20-30 ppm for phosphorus (P) and 150-170 ppm for potassium (K).

In addition, a small amount of sulfur (S) can be beneficial if planted in sandier soils, around 12 ppm. Calcium (Ca) is also necessary for growth, but typically additional Ca is not needed unless the soil is particularly lacking.

Weeding is also necessary during different alfalfa growth stages, especially germination time, as weeds can quickly choke out the plants. The plot of land should be as clear of weeds as possible, or else the alfalfa should be rotated with a crop such as corn or wheat to deter weeds from taking hold.

Also, pre-planting herbicides are often recommended to keep alfalfa safe.

Seed Selection

Numerous cultivars of alfalfa are available, for different needs and climates:

• Winter Hardiness: A balance must be maintained here, based on your climate. The plantings should be able to survive the winter, but excessive winter hardiness will reduce overall yield.
• Fall Dormancy: The less dormant the alfalfa is, the higher the overall yields will be — but it must still be able to survive the winter. Mid-range dormancy scores are typically best, but highly dependent on your local climate
• Disease resistance: Alfalfa is typically susceptible to diseases, with numerous cultivars bred for different resistances. Selection should be based on diseases commonly seen in your area.

Another question is whether to invest in regular seeds or choose more expensive coated seeds with extra fertilizer or antifungals included. Do coated alfalfa seeds bring a better yield? The evidence is mixed, with inconsistent results even in the same basic areas.

If your fields are known to host certain diseases or fungi that are harmful to alfalfa, buying coated seeds targeting those diseases is probably a good idea. However, it may not be worth buying coated seeds unless you have a specific reason. If you do buy coated seeds, remember that they will be both larger and heavier than normal ones, you may need to prepare your planting equipment appropriately.

In any case, always buy certified seeds to ensure the stands are disease-free.

Planting Guidelines

In most climates, alfalfa can grow for most of the year, aside from winter. In theory, it can be planted in spring, summer, or autumn. However, alfalfa seeds should not be planted in midsummer due to the high heat and most competition from weeds.

Otherwise, the optimal temperature range for planting alfalfa is around 65 and 77°F (18 and 25°C). Alfalfa will generally germinate faster in higher temperatures.

The seeds should always be planted less than 1 inch deep — typically 0.25-0.5 inches deep in clay soil, or 0.75 inches in sandy soil. Drill seeding is the best method, rather than broadcasting, since that can ensure the seeds are all planted at the optimal depth while ensuring they get plenty of water. Rows should be 18-24 inches apart.

In addition, the seeds must be inoculated with Rhizobium meliloti — a symbiotic fungus that helps legumes fix their nitrogen.

Irrigation and Water Management

Alfalfa is one of the thirstiest plants you can grow, and it will require substantial amounts of water. In general, alfalfa could need anywhere from 20-40 inches of water in a growing season, which probably will not be entirely provided by rainfall. Irrigation will likely be necessary because yield will be greatly reduced if it does not receive sufficient water. In general, assume that roughly half the water you provide will go to the plant, while the other half will evaporate or percolate downwards.

At the same time, avoid over-watering. Waterlogged soil will encourage root rot and stunted growth. Yellowing leaves are a sign that the plant is drowning. It is possible to kill alfalfa stands with overwatering, especially in high heat.

Fertilization and Nutrient Management

As a legume, most of the time, alfalfa may not require nitrogen (N) fertilizer — it creates its own nitrogen, alongside the Rhizobium meliloti in its root system. However, alfalfa does still require phosphorus (P) to encourage root growth, and potassium (K) to strengthen its disease resistance.

Always do a soil test before planting, and regularly throughout the season, to understand your existing nutrient levels. While individual fields will vary, the standard suggestion for ongoing alfalfa fertilization is 170-218 pounds per acre of potassium and 18-22 pounds per acre of phosphorus.

Also, be aware of the stand's micronutrient needs. Along with standard P & K fertilizers, alfalfa will need iron, manganese, chloride, boron, zinc, copper, and molybdenum. However, these are only required in trace amounts, less than five pounds per acre.

Weed, Pest, and Disease Control

Aside from the possibility of over-watering, the biggest threats to your alfalfa planting will come from weeds, diseases, and pests.

Weeds

Weeds can quickly choke out alfalfa — be prepared to use almost any means necessary to keep them from gaining a foothold. Many farms choose to use specific herbicide-tolerant varieties. Otherwise, keep up standard herbicides and hand-weeding to keep weeds in check. Agricultural cameras can also help you keep an eye on weed growth.
Companion plants such as oats, wheat, or corn can reduce weed growth — but they'll also take nutrients from the alfalfa and likely reduce yield somewhat.

Pests

Many insects seen in your alfalfa fields will be non-harmful, but there are a few to watch out for. In particular, cutworms, aphids, and alfalfa weevils can do the most damage to a field.


Visual observation or monitoring through agri-cameras are the best ways to keep an eye on potential infestations. Insecticides or manual destruction should be deployed immediately if any threats are spotted.

Diseases

In general, the best way to avoid alfalfa diseases is through crop rotation, typically with cereals and other forage grasses, every two years. This will prevent any alfalfa diseases from living in the soil past a particular harvest.


In addition, using coated seeds protected against certain diseases or fungi can help. Again, always be sure to buy your seeds from a certified dealer to ensure they come healthy and disease-free.

Harvesting Practices

Alfalfa grows quickly, and even in its first year, spring-planted alfalfa will typically bring two harvests. Three harvests are possible in the following years, with the largest yields coming in the second or third years.

Deciding when to harvest alfalfa is a balancing act: harvest too early — and you get high-quality alfalfa, but less yield. Wait too long, and you get a high yield of low-quality plants. Research has suggested that harvesting at the 10% bloom phase generally hits the best balance of yield, quality, and long-term plant health.

The other question is whether alfalfa should be stored as silage or hay. Silage is more complicated, as it requires anaerobic storage which can be expensive to maintain. However, silage brings more nutrient content and is more easily digestible by a wider variety of animals.

Hay, on the other hand, is exceedingly simple to create and store, but is less nutritious overall. Your own economic situation and goals will dictate which approach is better for you.

When you have questions, we'll help you find the answers you need to take control of your fields and the harvest you care about. Contact Cropler to discover more about our products and the ways we help you proactively protect your operations from the effects of crop diseases. Learn More

Common Mistakes to Avoid

Planting Too Deep

Never sow alfalfa deeper than one inch. Plants will struggle to germinate and reach air, and may even die underground.

Forgetting Inoculation

Again, Rhizobium meliloti is necessary for alfalfa to properly fix nitrogen, as well as contribute it back to the soil. Always inoculate with this necessary fungus.

Ignoring Soil pH

Never plant alfalfa in acidic fields — it needs a neutral to slightly alkaline environment. If your fields have been acidified by nitrogen fertilizer, they'll need to be improved before alfalfa can be grown.

Overcutting in the First Year

Don't be too heavy-handed with your first-year harvests. Leave enough stubble that the plants can easily regrow in future years. In year two and onward, you can harvest more intensively as the plants’ root systems will be well-established by that point.

Conclusion

In short, alfalfa is a highly reliable and fairly hardy cash crop that is constantly in demand around the world. Given its low input costs and high multi-harvest yields, it can be a good moneymaker as long as it's raised properly.

Cropler can help! We aim to make cutting-edge technology available to farms of all sizes, combining robust Internet-connected cameras and sensors with a cloud-based web platform for data collection and analysis.

Contact us to learn more!

Resources

1. Coated Alfalfa Seed, is It Worth It? Dr. Richard Leep, James DeYoung and Dr. Doo-Hong Min. Michigan State University, Department of Crop and Soil Sciences
2. Balancing Yield, Quality, and Persistence. January 2004. Steve Orloff, Dan Putnam