When is the Best Time to Transplant an Alfalfa Plant?

Alfalfa, also known as lucerne, is a perennial flowering plant that is commonly grown as livestock feed. It is highly nutritious, producing high yields of protein-rich hay. Many farmers choose to start alfalfa from transplants, rather than direct seeding. But when is the ideal time to transplant alfalfa?

Why Transplant Alfalfa?

There are a few key reasons why a farmer may opt to transplant alfalfa instead of direct seeding:

• More reliable stand establishment – Transplanted alfalfa has higher and more uniform germination rates compared to direct seeding This leads to a thicker, more productive stand of alfalfa

• Quicker establishment – Transplants establish faster than seeds since the plants are already partially grown when planted This allows the alfalfa to be harvested sooner

• Weed control – Transplanting gives alfalfa a head start on any weeds The larger transplants can outcompete weed seedlings,

• Extend growing season – Using transplants allows the alfalfa growing season to start a few weeks earlier than direct seeding.

Spring is Best for Transplanting Alfalfa

The ideal window for transplanting alfalfa is in spring, from mid-spring through late spring. This timing maximizes the success and productivity of the alfalfa stand.

Why Spring Works Best

There are a few key reasons why spring is the prime season for transplanting alfalfa:

• Soil temperatures – Alfalfa requires warm soil to grow vigorously and become established. Soil temperatures in spring are ideal, generally above 50°F (10°C).

• Moisture – Spring soils often have good moisture levels from winter precipitation and snowmelt. This provides the right conditions for new transplants.

• Sunlight – Increasing daylight in spring fuels growth and productivity of the young alfalfa plants.

• Growing season – Transplanting in spring allows the alfalfa to become established and grow for the majority of the frost-free growing season.

• Weed pressure – Many annual weed species have not yet germinated in spring, giving the alfalfa transplants time to grow before weed competition.

• Stress avoidance – Summer heat and drought can stress and damage young alfalfa transplants. Transplanting in spring avoids these harsh conditions.

Step-by-Step Spring Transplanting

If spring transplanting is planned, here are the key steps:

• Start alfalfa seeds indoors 6-8 weeks before the last expected frost date. Use individual pots or trays.

• Harden off seedlings for 7-10 days by setting them outdoors to transition. Bring in at night if frost threatens.

• Prepare transplant beds by tilling soil and removing any debris. Mix in compost or fertilizer if needed.

• Transplant after daytime temps are reliably over 50°F and no freezing nights are forecast.

• Space plants 12-18 inches apart in rows spaced 2-3 feet apart. Dig holes and water transplants after planting.

• Ensure plants receive 1-2 inches of water per week from rain or irrigation for the first 2 months.

• Scout for pests and diseases. Apply insecticides or fungicides if infestations occur.

• Harvest the first cutting about 60-70 days after transplanting.

Summer Transplanting Can Stress Alfalfa

While spring is ideal, some growers opt to transplant alfalfa over the summer months. However, summer transplanting is riskier and can put more stress on the young alfalfa plants.

Challenges of Summer Transplanting

If transplanting in summer, be aware of these key challenges:

• Heat – Hot summer temperatures, especially over 90°F, can shock transplants and stunt growth. Gradual hardening off is critical.

• Drought – Lack of rainfall in summer means diligent irrigation is needed to establish transplants. Moisture stress will reduce growth.

• Weeds – Weeds grow rapidly in summer. Transplants will need to compete with well-established weeds.

• Pests – Hot, dry conditions favor higher populations of alfalfa weevils, aphids, leafhoppers and other pests.

• Reduced yield – Due to stress, summer-transplanted alfalfa often has lower productivity the first year compared to spring plantings.

• Shortened stand life – Heat and drought reduced root reserves in the first year, decreasing the lifespan of the alfalfa stand.

Tips for Summer Transplanting

If summer transplanting can’t be avoided, here are some tips to maximize success:

• Prioritize irrigation – ensure transplants receive 1-2 inches of water per week, avoiding moisture stress.

• Use raised beds to improve drainage and reduce root rot in wet summers.

• Transplant in the morning or evening when temperatures are lower to avoid midday heat.

• Use a starter fertilizer when transplanting to support initial growth.

• Scout vigilantly for pests like alfalfa weevil that thrive in hot weather.

• Harvest the first cutting later to allow more established growth before cutting.

• Be prepared to renovate or reseed if the stand is poor – summer transplants often have higher failure rates.

Can Alfalfa Tolerate Partial Shade?

Alfalfa thrives best in full sunlight. But some shade can be tolerated, especially in hot climates where partial shade provides a break from excessive heat and drought pressure.

How Much Shade can Alfalfa Handle?

• Alfalfa can tolerate partial shade, but growth will be reduced compared to full sun conditions.

• Generally alfalfa can thrive with up to 50% shade throughout the day.

• Light levels below 50% shade will start to significantly depress productivity.

• If shade is more than 70% over the course of a day, the alfalfa stand will likely fail.

• Morning sun is particularly important, so avoid shade on the east side of plantings.

Effects of Shade on Alfalfa

When grown in partial shade, alfalfa exhibits some of these effects:

• Slower germination and emergence of new seedlings.

• Looser, more open growth habit as plants reach for sunlight.

• Reduced shoot and root mass as energy production decreases.

• Lower yields at harvest time, producing less tons of hay per acre.

• Increased susceptibility to fungal diseases like spring black stem.

• Greater weed pressure as the alfalfa is less competitive.

• Thinner stands over time as individual plants are weakened.

• Potentially lower feed quality and protein content.

Should Alfalfa be Planted in Shade?

While alfalfa can tolerate some shade, it performs best in full sun. Before planting alfalfa in a shaded area:

• Assess the amount and timing of shade to determine if light levels are adequate for growth.

• Test the soil – shade can lead to wetter, cooler, more acidic soils. Adjust pH and improve drainage if needed.

• Select an alfalfa variety adapted to partial shade if available.

• Prepare for potential disease and weed pressure. Have a management plan for these issues.

• Reduce stocking rates and expect lower yields compared to sunny fields.

• Monitor stands closely and be ready to renovate or reseed thin areas.

While challenging, with care alfalfa can produce reasonably well in partly shaded areas. But full sun is ideal for maximum production from alfalfa.

Determining the best transplant window is an important decision when establishing an alfalfa crop. Spring almost always provides the ideal conditions for planting and growing vigorous alfalfa transplants. Transplanting in summer is riskier, but can work with careful management. While alfalfa strongly prefers full sun, it can tolerate partial shade of 50% or less. But be prepared for potential reductions in productivity. With attention to timing and management, transplanting alfalfa can lead to a productive stand that provides high-quality forage for years to come.