When to plant scallions (green onions) in Billings, Montana

April 12 – April 26

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 scallions (green onions) 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 12 – Apr 26

Fall plantingAug 6 – Sep 3

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

Scallions (Green Onions) in Billings · freeze context from Billings Wtp, MT, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Apr 12 – Apr 26

Colorado State University Extension's CMG GardenNotes #720 groups onions with the Hardy Vegetables that may go in "As early as 2-4 weeks before the date of the average last spring frost," and the same publication's Table 1 Cool Season Vegetable Planting Guide lists "Onions, green" among those cool-season crops, so the 2-to-4-week pre-frost span is used directly; no other extension source located gave a later-starting green-onion spring rule, so nothing needed reconciling. Anchored to the median last spring freeze (May 10). Colorado State University Extension (Colorado Master Gardener)

Fall planting

Aug 6 – Sep 3

Purdue Extension HO-186-W Table 2 lists green onion among cool-season plants for late-summer or fall planting to be planted "at least 4-8 weeks before first fall frost," which encodes as a window running from eight weeks down to four weeks ahead of the first fall freeze; it was the only extension source found anchoring a green-onion fall sowing to frost, so it stands unreconciled. Anchored to the median first fall freeze (Oct 1). Purdue University Extension, Department of Horticulture and Landscape Architecture

Variety assumption: Assumes non-bulbing bunching types or true onions pulled young; Colorado State's Table 1 gives 60 typical days to harvest for "Onions, green" versus 110 for dry onions, and this entry encodes only the green-onion crop.

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)

Colorado State University Extension (Colorado Master Gardener): CMG GardenNotes #720: Vegetable Planting Guide (accessed 2026-07-25)
"Hardy Vegetables ... Crops: broccoli, cabbage, kohlrabi, onions, lettuce, peas, radish, spinach, turnips"
Purdue University Extension, Department of Horticulture and Landscape Architecture: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-25)
"Table 2. Cool season plants for late-summer or fall planting (plant at least 4-8* weeks before first fall frost) (See Figure 2)"

Keep exploring

This crop, other cities

Related crops in Billings

Local overview