Alfalfa in the Garden: Understanding This Non-Native Perennial
You might know alfalfa (Medicago sativa) as livestock feed, but this hardy perennial legume has caught the attention of some gardeners for its unique properties. Also called lucerne, this non-native plant has quite a story to tell and some interesting characteristics that might surprise you.
What Exactly Is Alfalfa?
Alfalfa is a forb – essentially a non-woody plant that lacks the thick, woody stems you’d find on shrubs or trees. Instead, it produces soft, herbaceous growth with fine-textured green foliage and can live for many years as a perennial. This plant grows upright in a single crown formation and can reach about 2 feet tall at maturity.
Where Does Alfalfa Come From and Where Does It Grow?
Originally from the Mediterranean region and southwestern Asia, alfalfa is completely non-native to North America. However, it has established itself across virtually the entire continent, from Alaska to Puerto Rico and from coast to coast. You’ll find it growing in all 50 states, all Canadian provinces, and U.S. territories.
The Garden Appeal (Or Lack Thereof)
Let’s be honest – alfalfa isn’t winning any beauty contests. While it does produce small purple flowers in spring that are somewhat conspicuous, the brown seeds that follow aren’t particularly showy. The fine-textured foliage is pleasant enough, but this plant is more about function than form.
What alfalfa lacks in ornamental value, it makes up for in rapid growth and impressive root depth. Those roots can extend 24 inches deep or more, making it excellent for soil improvement and erosion control.
Why (Or Why Not) Plant Alfalfa?
Here are some reasons you might consider alfalfa:
- Nitrogen fixation: Like other legumes, alfalfa pulls nitrogen from the air and adds it to the soil
- Wildlife food: Provides 5-10% of the diet for various birds and 2-5% for small mammals
- Pollinator support: The purple flowers attract bees and butterflies
- Drought tolerance: Once established, it handles dry conditions well
- Rapid regrowth: Bounces back quickly after cutting or grazing
However, consider these drawbacks:
- Non-native status: It doesn’t support native ecosystems as well as indigenous plants
- High fertility needs: Requires rich, well-fertilized soil to thrive
- Can cause bloat: Problematic if you have grazing animals
- Known allelopath: May inhibit growth of nearby plants through chemical compounds
Native Alternatives to Consider
Since alfalfa is non-native, you might want to explore indigenous nitrogen-fixing legumes instead. Consider native clovers, wild lupines, or other regional legumes that provide similar soil benefits while supporting local wildlife and ecosystems more effectively.
Growing Conditions and Care
If you do decide to grow alfalfa, here’s what it needs:
Soil: Prefers medium to fine-textured soils with excellent drainage. It’s quite tolerant of alkaline conditions (pH 6.0-8.5) and even handles some salinity.
Sunlight: Full sun only – this plant is completely intolerant of shade.
Water: Moderate to high moisture needs, though it becomes drought-tolerant once established thanks to those deep roots.
Climate: Hardy in USDA zones 3-9, tolerating temperatures as low as -43°F. Needs at least 90 frost-free days and annual precipitation between 12-65 inches.
Planting and Propagation
Alfalfa is grown exclusively from seed – no fancy propagation methods needed. With about 226,800 seeds per pound, a little goes a long way! The seeds are routinely available commercially and show high abundance and vigor when planted.
Plant in spring for best results, and don’t expect it to spread quickly on its own – both seed and vegetative spread rates are slow. However, once established, expect rapid growth during the active growing season of spring through fall.
Special Considerations
Keep in mind that alfalfa is an obligate upland plant in most regions, meaning it almost never grows in wetlands. The exception is the Midwest, where it’s classified as facultative upland and may occasionally appear in wet areas.
This plant also has some quirks worth knowing about. It can regrow rapidly after harvest or cutting, making it potentially useful for areas that need frequent maintenance. However, its allelopathic properties mean it might not play well with other plants nearby.
The Bottom Line
Alfalfa is a hardworking, if not particularly glamorous, addition to specific garden situations. While it’s non-native, it’s not considered invasive and can serve useful purposes in the right context. However, for most ornamental gardens, you’ll probably find better options among native plants that provide similar benefits while supporting local ecosystems. Consider alfalfa for agricultural areas, erosion control, or wildlife food plots rather than traditional flower beds or landscape gardens.
