When to plant carrots in Billings, Montana

April 26 – May 10

Direct-sow outdoors · typical Billings year

Climate basis: NOAA station Billings Wtp, MT (USC00240802), 13 mi (21 km) from downtown Billings (ZCTA 59101 centroid), elevation 3097 ft, on the 1991–2020 climate normals. Direct-sow carrots from approximately the dates above, anchored to the median last spring 32°F freeze (May 10). One year in ten still freezes after May 24.

Last spring freezeMay 101-in-10 after May 24

First fall freezeOctober 11-in-10 before Sep 19

Frost-free season≈ 142 daysmedian at 32°F

Hard freeze, 28°Apr 27 – Oct 12kills even hardy greens

USDA zone5a-20 to -15°F winter low — not frost timing

The Billings year

Direct-sow outdoorsApr 26 – May 10

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 24

Carrots in Billings · freeze context from Billings Wtp, MT, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Apr 26 – May 10

Purdue: semi-hardy — 2–4 weeks before the last frost; Penn State's earliest sowing is Apr 17 for a May 1 frost (−14 days). The later Penn State start is used. Anchored to the median last spring freeze (May 10). Penn State Extension (York County Master Gardeners) · Purdue University Extension

Start seeds indoors

Not calculated

Root crops are not transplanted; carrots are direct-seeded.

Transplant outdoors

Not calculated

The cited extension guides do not time an outdoor transplanting window for this crop.

Fall planting

Not calculated

No source-backed fall planting rule exists for this crop in the registry, so no fall window is calculated.

Variety assumption: Assumes an average main-crop variety (about 65–80 days; Penn State lists 75).

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

This week, not a typical year:

Crop rule sources (2)

Penn State Extension (York County Master Gardeners): Vegetable Seed Planting Guide (accessed 2026-07-24)
Earliest/latest sowing dates for a May 1 last-frost / Oct 1 first-frost baseline; offsets derived by date difference from May 1. Also days-to-maturity figures.
Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.

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