Idaho planting calendar

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

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

Turnips planting timetable for Idaho

Stage	When in Idaho	Anchor
Direct-sow outside	mid-April (April 17)	28 days before the last frost (mid-May)
First harvest (estimate)	early June (June 6)	~50 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 turnips 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 — turnips bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Turnips are direct-sown cool-season roots that tolerate hard frost — seedlings survive down to about -4 °C once established. Sow 3-5 weeks before the last spring frost for a late-spring harvest; a fall sowing 6-8 weeks before first fall frost is often preferred since mild frost actually sweetens the roots. Harvest roots at 2-3 inches diameter; roots left longer turn woody. Greens ('turnip tops') can be cut at any size and are ready in 30-35 days.

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: 7-29 °C (45-85 °F).
Spacing: 4-6 inches (10-15 cm) between plants.
Days to harvest: ~50 days from planting out.

Frequently asked questions

When is the best time to plant turnips in Idaho?

In Idaho (mostly USDA zone 6a), direct-sow turnips mid-April (before the last frost, mid-May), and harvest from early June. Turnips are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

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 turnips in Idaho?

Yes. Idaho's dominant zone 6a supports turnips — the key is timing. Turnips are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

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.