State × crop calendar
Alfalfa planting in Oregon.
- Secondary crop
- Zone 8a
- 185-day season
- Last frost April 20
- Forage
- Frost Hardy
Alfalfa planting in Oregon is shaped by the state's 8a dominant hardiness zone, last frost date around April 20, and a 185-day growing season. Alfalfa is grown in Oregon but is not a dominant crop — works for home gardens, food plots, and some commercial production.
Planting dates on this page are climatological estimates from USDA frost-date norms and zone-typical planting offsets. Verify against OSU Extension Service for variety- and county-specific guidance.
Planting calendar — 2026
Frost-anchored windows.
Alfalfa · Oregon · planting calendar
Planting windows shift earlier in southern parts of the state and later in northern parts. Use last frost date in your specific county as the reference.
Planting windows
Earliest → ideal → latest.
Spring planting
AlfalfaEarliest
March 30
Ideal start
April 13
Ideal end
May 11
Latest
June 1
Soil-temp trigger
Spring seeding: cool-season germination at 45°F+. Fall seeding: 60-90 days before first hard freeze for establishment.Fall planting
AlfalfaEarliest
August 6
Ideal start
August 21
Ideal end
September 5
Latest
September 20
Soil-temp trigger
Spring seeding: cool-season germination at 45°F+. Fall seeding: 60-90 days before first hard freeze for establishment.Harvest window
Typical start
June 12
Typical end
July 12
Harvest timing varies with planting date and seasonal weather — these dates are typical for the ideal planting window.
Growing notes
Alfalfa can be successfully grown in Oregon with attention to variety selection. The state's 185-day growing season requires choosing varieties appropriate for the growing window.
Alfalfa is grown in Oregon but is not a dominant crop — works for home gardens, food plots, and some commercial production.
Agronomy reference
Alfalfa fundamentals.
Soil-temp minimum
45°F
Soil-temp optimum
50–75°F
Days to maturity
60–90
Water (in/wk)
0.7–1"
Soil pH
6.5–7.5
Nitrogen demand
low
Establishment year produces limited harvest. Stand life 4-6 years with proper management. Spring vs. fall seeding strategy varies by region.
Common pests to watch
- Alfalfa weevil
- Potato leafhopper
- Aphids
Pest pressure varies by region and year. Confirm current outbreaks with OSU Extension Service.
Common diseases
- Sclerotinia crown rot
- Verticillium wilt
- Phytophthora root rot
Resistance varieties shift each year. Check the current variety trial report for your state.
Variety selection
Alfalfa varieties for Oregon live with your extension.
Variety selection
Variety performance is micro-regional and changes with each year's trial cycle. We don't republish variety lists — instead, we point directly at the source.
OSU Extension Service →Search the extension site for “alfalfa variety trial” or “recommended alfalfa varieties” to find the current report.
Yield varies significantly by variety, soil, fertility, and management. Consult your state extension service for variety performance trials in your region.
Alfalfa timing. Live alerts.
Bield: Farm ties weather and soil-temperature stations in your county to crop planting thresholds — get notified the day soil temp clears your target window.
Start free trial →