How to Grow Alfalfa 'WL 920'
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Alfalfa 'WL 920'
Medicago sativa L.
herbWL 920 is a winter-dormant alfalfa variety bred for cold-hardy perennial growth in northern climates. This cultivar combines excellent forage quality with superior winter survival, making it ideal for hay production and livestock feed in harsh winters. The variety is known for its consistent regrowth after cutting and disease resistance.
When should you plant Alfalfa 'WL 920' in your zone?
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Example Alfalfa 'WL 920' timeline · Pittsburgh, PA (Zone 6b)
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Plant Alfalfa 'WL 920'
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Alfalfa 'WL 920'
Around Jun 6≈ 50 days after planting
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 2-7; winter dormancy makes it ideal for cold northern regions
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Germination & Seedling
2-4 weeksSeeds germinate in 5-10 days; seedlings emerge with cotyledons and first true leaves. Root system develops rapidly, with the characteristic taproot forming early.
Keep soil consistently moist but not waterlogged during germination. Avoid foot traffic on seedling beds. Thin seedlings if overcrowded. Protect from livestock grazing until plants are well-established (6-8 weeks).
Vegetative Growth & Establishment
6-12 weeks (first season)Plant develops compound pinnate leaves and branching stems. Deep taproot extends downward while above-ground growth strengthens. Multiple shoots emerge from the crown.
Monitor for weeds and remove competing vegetation. Do not graze or harvest during first growing season to allow root development. Water during dry periods. In fall, allow plant to harden off for winter dormancy.
Winter Dormancy
3-4 months (November-March in northern climates)Above-ground growth ceases and plant goes dormant. Crown remains alive with stored carbohydrate reserves. Vernal dormancy type means early spring growth compared to non-dormant varieties.
No active management needed. The dormancy trait of WL 920 provides winter hardiness and prevents winter injury from freeze-thaw cycles. Mulching not necessary in dormant varieties.
Spring Regrowth & Cutting Cycles
4-6 months (April-October)Plant breaks dormancy in early spring with vigorous shoot growth. Reaches boot to bloom stage in 40-50 days. Multiple flushes of growth occur throughout the season.
First harvest at late boot to early bloom stage (before flowers fully open) for best forage quality. Harvest every 28-35 days during growing season. Remove 3-4 inches of top growth, leaving 2-3 inches of stubble. Avoid harvesting after September 1 in northern zones to allow regrowth before dormancy.
Harvest & Post-Harvest
Ongoing throughout growing seasonMature hay is dried to 15-20% moisture before baling. Quality is highest when harvested at pre-bloom to early-bloom stage.
Cure hay properly in field (2-3 days in good weather). Bale at optimal moisture to prevent mold. Store in dry location. WL 920 hay has high protein content (18-20%) and palatability for livestock. Can also be grazed rotationally.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Harvest early to disrupt life cycle; use Bacillus thuringiensis (Bt) biological control; maintain good stand vigor; insecticides if populations exceed thresholds
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Monitor with sticky traps; early harvest reduces populations; resistant varieties help; predatory insects; insecticidal soap if severe
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Harvest frequently; use resistant varieties like WL 920; maintain plant vigor; natural predators and parasitoids; spray with neem oil if needed
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Scout plants regularly; early harvest before major feeding; Bt products; encourage parasitic wasps
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and
(Fusarium species)
Use resistant varieties; ensure good drainage; avoid overwatering; crop rotation; remove and destroy infected plants; proper stand management
Uses
Livestock Feed & Hay Production
CulinaryWL 920 is primarily grown as a high-protein forage crop for cattle, horses, sheep, and other livestock. The hay is nutrient-dense with 18-20% crude protein and excellent digestibility when harvested at proper growth stage. [source]
Herbal Medicine & Supplements
MedicinalAlfalfa is traditionally used in herbal medicine for nutritional supplementation, containing vitamins K, A, D, and minerals including calcium, magnesium, and iron. Modern supplements often use alfalfa leaf meal and extracts. [source]
Soil Improvement & Nitrogen Fixation
HouseholdAlfalfa's symbiotic relationship with Rhizobium bacteria allows it to fix atmospheric nitrogen, enriching soil naturally. The deep taproot breaks up compacted soil and improves soil structure when incorporated. [source]
Pollinator & Wildlife Habitat
WildlifeAlfalfa flowers attract honeybees, native bees, and butterflies, supporting pollinator populations. The dense stand provides habitat for beneficial insects and nesting cover for ground-nesting birds. [source]
Sprouts & Human Consumption
CraftAlfalfa seeds can be sprouted for use in salads and sandwiches, providing fresh microgreens rich in enzymes and nutrients. Some regions also use young alfalfa shoots as a vegetable. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Harvest alfalfa WL 920 at late boot to early bloom stage for maximum forage quality and protein content. For hay, cut when lowest flower buds appear but blooms haven't fully opened. Cut to 2-3 inches above soil surface to encourage regrowth from crown. In northern climates, stop harvesting after September 1 to allow plant to accumulate reserves before dormancy. For grazing, use rotational system with 28-35 day regrowth cycles. Typical yield is 4-6 tons dry matter per acre annually in optimal conditions.
Fun Facts
- 🌱 The name 'alfalfa' comes from the Arabic word 'al-fal-fa' meaning 'father of all foods,' reflecting its historical importance as a livestock feed and soil improver.
- 🌱 WL 920's 'vernal dormancy' classification means it enters dormancy in response to decreasing day length in fall, providing superior winter hardiness compared to non-dormant varieties—a critical breeding trait for northern climates.
- 🌱 Alfalfa's taproot can extend 15 feet or deeper into the soil, allowing it to access water during droughts and improving soil aeration far below the surface.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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