Generally — Most Areas
Ethiopian mustard (zones 4-10) suits most of Montana (3a-6b) — zones 4-6 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Ethiopian Mustard is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Montana site runs ~151 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score ethiopian mustard against your land's actual frost dates, sun, and soil.
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Zone Comparison
Ethiopian Mustard Needs
- USDA Zones: 4-10
- Sun: Full Sun
- Mature size: 4 ft tall
- Drought tolerance: Medium
Montana Has
- USDA Zones: 3a-6b
- Last Hard Freeze (28°F): May 2 - May 13
- First Hard Freeze (28°F): Sep 28 - Oct 7
- Annual Rainfall: 10-20 inches
- Common Soils: Sandy loam, Clay, Glacial till
Plant Zone Range (zones 4-10)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Ethiopian Mustard in Montana
The frost window
Across Montana, the last spring hard freeze (28°F) clears between May 2 and May 13, and the first fall hard freeze lands between Sep 28 and Oct 7 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 138-day window you can count on — up to 158 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Frost tenderness
Ethiopian Mustard is frost-tender — its listed minimum temperature is 41°F (USDA PLANTS Database) — so set plants out two to three weeks PAST your local last hard freeze, not on it and not on the state's earliest date. The 28°F marker above is when killing freezes stop, not when light frost does.
When to start the seed
Ethiopian Mustard is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Montana's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Days to maturity vs. the window
At 90 days to maturity (USDA PLANTS Database), counting from the last hard freeze it ripens with 48 days to spare even in Montana's tightest freeze scenario — room for a later start or a second sowing.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says ethiopian mustard survives winter in part of Montana, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Days to maturity
Ethiopian Mustard matures in ~90 days (Growable Ground Plant Database). A typical Montana site has ~151 frost-free days, so plenty of room for a second succession.
Growing degree days
Ethiopian Mustard needs ~1400 GDD (base 50°F) to ripen. The state median runs ~1769 GDD (from PRISM 1991-2020 climate normals), so Montana's typical season clears that easily.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Ethiopian Mustard tolerates a wide pH range (pH 5-8.5) — 3.5 units, acid ground through alkaline — so soil acidity is rarely what limits it in Montana. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 5.5 and 8 — worth knowing before you decide whether a Montana soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Montana site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH and drainage requirements from USDA PLANTS Database. Montana soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Ethiopian Mustard in Montana — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 4-10 (USDA PLANTS Database)
- State Zones: 3a-6b (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about May 2 - May 13 to Sep 28 - Oct 7 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 90 days
What Else to Consider for Ethiopian Mustard in Montana
Zone compatibility tells you about winter cold survival — but Montana growers also need to think about:
Very short growing season (60-100 frost-free days)
Low rainfall requires irrigation in most areas
Extreme winter cold (-40F possible)
What to actually do about these — and the constraints that apply to every Montana grower, not just ethiopian mustard — is covered on the Montana growing guide.
Timing shifts within Montana
Ethiopian Mustard needs about 90 days of frost-free season from planting to harvest. 55 of Montana’s 56 counties give it that outright. The tightest that does is Gallatin County at 114 frost-free days — 24 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Montana’s 56 counties the frost-free season runs from 59 days in Deer Lodge County to 170 days in Petroleum County — a spread of 111 days, which is why a single statewide planting date misleads. The median Montana county sees 151 frost-free days, leaving ethiopian mustard about 61 days of slack on a typical parcel — room for a second sowing where the season runs long.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Ethiopian Mustard's 90-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Where in Montana Fits Best
Even within Montana's zones 3a-6b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for ethiopian mustard (USDA PHZM 2023):
Pollinator + Wildlife Value
Ethiopian Mustard draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, ethiopian mustard can only work that bloom inside Montana's frost window — roughly 151 days, opening after the last 28°F freeze (May 2 - May 13) and closing at the first (Sep 28 - Oct 7), per NOAA Regional Climate Centers ACIS, 1991-2020.
Montana Cooperative Extension
For Montana-specific cultivar recommendations, planting calendars, and pest pressure for ethiopian mustard, the canonical source is Montana State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Ethiopian Mustard native to Montana?
No — the USDA PLANTS Database lists Ethiopian Mustard as introduced rather than native in the Lower 48, so it is not part of Montana's native flora. It grows here as a garden plant; pairing it with a few Montana natives keeps local pollinators fed too.
Looking for plants that belong here? The Montana growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Ethiopian Mustard in Montana
When can I plant Ethiopian Mustard in Montana?
Montana's last spring hard freeze (28°F) clears between May 2 and May 13, and the first fall hard freeze lands between Sep 28 and Oct 7 (NOAA Regional Climate Centers ACIS, 1991-2020). Ethiopian Mustard is frost-tender — its listed minimum temperature is 41°F (USDA PLANTS Database) — so wait two to three weeks past your site's last hard freeze, when light frost has also stopped, before planting out.
Can Ethiopian Mustard mature before first frost in Montana?
Yes — Ethiopian Mustard matures in 90 days (USDA PLANTS Database), and Montana's dependable hard-freeze-free window runs 138 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 48 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Ethiopian Mustard grown in across Montana?
Montana spans USDA hardiness zones 3a-6b (USDA ARS PHZM 2023). Ethiopian Mustard carries a range of zones 4-10, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Montana site have?
A typical Montana site sees ~151 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Ethiopian Mustard should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Ethiopian Mustard native to Montana?
No — the USDA PLANTS Database lists Ethiopian Mustard as introduced rather than native in the Lower 48, so it is not part of Montana's native flora. It grows here as a garden plant; pairing it with a few Montana natives keeps local pollinators fed too.
How should I amend the soil for Ethiopian Mustard in Montana?
Ethiopian Mustard tolerates pH 5-8.5 and well (dry spells) drainage (FAO ECOCROP). That is a 3.5-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Montana site — amend for drainage and organic matter first.
Will Ethiopian Mustard actually grow on my specific land in Montana?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores ethiopian mustard against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Montana
State-level data is a sketch. Your Growable Ground report scores ethiopian mustard against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Montana ethiopian mustard averages can't show:
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