Idaho planting calendar

When to plant fava beans in Idaho — sow, transplant & harvest dates

Idaho is mostly USDA zone 6a (range 3a-7a). Dates below are derived from fava beans's frost tolerance and Idaho's frost window — not generic national averages.

Fava Beans planting timetable for Idaho

Stage	When in Idaho	Anchor
Direct-sow outside	early April (April 3)	42 days before the last frost (mid-May)
First harvest (estimate)	early July (July 2)	~90 days from direct sow

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Idaho's climate shifts the fava beans dates

Idaho's last spring frost averages mid-May and first fall frost late September, which sets the whole planting clock. Idaho ranges from cold mountain valleys to the mild Treasure Valley. The lower Snake River Plain has the longest, warmest season. Sow early — fava beans bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

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.

Frost-risk note

Don't plant before mid-May — a hard freeze can still set young plants back. In the central mountains and high valleys (zone 3a-4b) the safe date runs a week or two later.

Regional variation within Idaho

the central mountains and high valleys (zone 3a-4b) runs roughly 1-2 weeks behind the state average; the Treasure Valley around Boise (zone 7a) can plant 1-2 weeks earlier.

Boise — USDA zone 7a
Idaho Falls — USDA zone 5a
Pocatello — USDA zone 6a
Coeur d’Alene — USDA zone 6b

What else to plant in Idaho around then

The same early window suits peas, lettuce, spinach, and onion sets.

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: ~90 days from planting out.

Frequently asked questions

When is the best time to plant fava beans in Idaho?

In Idaho (mostly USDA zone 6a), direct-sow fava beans early April (before the last frost, mid-May), and harvest from early July. Fava Beans are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

What USDA zone is Idaho?

Most of Idaho sits in USDA hardiness zone 6a, with the state spanning roughly 3a-7a from the central mountains and high valleys (zone 3a-4b) to the Treasure Valley around Boise (zone 7a). The last spring frost averages mid-May and the first fall frost late September.

Can you grow fava beans in Idaho?

Yes. Idaho's dominant zone 6a supports fava beans — the key is timing. Fava Beans are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

Does the planting date change across Idaho?

the central mountains and high valleys (zone 3a-4b) runs roughly 1-2 weeks behind the state average; the Treasure Valley around Boise (zone 7a) can plant 1-2 weeks earlier.

What else can I plant in Idaho around the same time?

The same early window suits peas, lettuce, spinach, and onion sets.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.