USDA Zone 4 planting calendar
When to plant fava beans in USDA zone 4
Sowing, transplant, and harvest dates calibrated to zone 4's 125-day season (Northern Maine, northern Wisconsin, Montana, parts of New England).
Key dates for fava beans in zone 4
| Stage | When | Anchor |
|---|---|---|
| Direct sow outdoors | early April (April 3) | 42 days before last frost (mid-May) |
| First harvest (estimate) | early July (July 2) | ~90 days from sow |
Dates are zone-wide averages. Local microclimates (south-facing slopes, urban heat, lakeside warmth, elevation) can shift the planting window by 1-2 weeks within the same zone.
Why this timing works for zone 4
Zone 4 has average annual minimum temperatures of -30 to -20°F and a 125-day frost-free window from mid-May to mid-September. Fava Beans are hardy enough to handle light frost — and in fact prefer cool weather. They bolt or turn bitter once daytime temperatures consistently climb above 24 °C, which is why earlier is better in zone 4.
Direct sow 4–6 weeks before last frost in spring (soil as cool as 40 °F/4 °C is acceptable); established plants tolerate light frost to about 21 °F (-6 °C) but flowers and young pods are frost-sensitive. Pods fail to set when daytime temperatures exceed 75 °F (24 °C), so early sowing is critical — the crop must finish before summer heat arrives. In zones 9–11 fava beans are a fall/winter crop (sow October–December); they are impractical as a spring crop in those zones.
Quick-grow guide
- Sun: Full sun — 6+ hours direct.
- Soil temperature for germination: 7–21 °C (45–70 °F); optimal 15–18 °C (60–65 °F).
- Spacing: 6–9 inches (15–23 cm) plants; 18–24 inches (45–60 cm) between rows between plants.
- Days to harvest from direct sow: ~90 days.
- Plant in cool weather and provide afternoon shade once temperatures climb above 24 °C.
Common mistakes — zone 4 × fava beans
- Planting before last frost: zone 4's last frost averages mid-May, and even a light frost will kill fava beans seedlings overnight.
- Skipping hardening off: even healthy indoor transplants need 7-10 days of progressive outdoor exposure before going in the ground.
Source and methodology
Frost-date averages from NOAA Climate Data Online within each USDA hardiness zone. Hardiness zone boundaries from the USDA Plant Hardiness Zone Map (2023). Crop timing offsets calibrated against US Cooperative Extension Service publications (UNL, UMN, NC State, Texas A&M, UF/IFAS) and cross-checked against the RHS sowing calendar for en-GB readers. Curated by the Growli editorial team.
Keep going
- How to grow fava beans — full guide
- USDA Zone 4 — frost dates and what else to plant
- All 13 USDA hardiness zones
Same crop, nearby zones
- When to plant fava beans in USDA zone 2
- When to plant fava beans in USDA zone 3
- When to plant fava beans in USDA zone 5
- When to plant fava beans in USDA zone 6