Generally — Most Areas
black mustard (zones 6-10) suits most of Utah (4a-9a) — zones 6-9 are in range, and the rest of the state is the exception.
Black Mustard in Utah — the short answer
Black Mustard in Utah: hardy in zones 6–10, full sun, against a state median of ~175 frost-free days.
- Plant zones
- 6-10
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Utah zones
- 4a-9a
- USDA PHZM 2023
- Frost window
- Apr 12 - May 6 – Oct 8 - Oct 27
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 98 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 60 days
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Black Mustard is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Utah site runs ~175 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 black mustard against your land's actual frost dates, sun, and soil.
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Utah is not one climate
A single Utah answer averages 29 counties whose growing seasons are 139 days apart — from 98 frost-free days in Summit County to 237 in Washington County. Which end of that your land sits nearer changes what black mustard can finish before the first hard freeze.
The middle half of 29 counties runs 156–195 days, with a median of 175 days — a 139-day span end to end.
Measured across 29 Utah counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Utah Fits Best
Black Mustard is rated for zones 6–10 — a cold floor USDA puts at -10 to 0°F. Against Utah’s 29 counties that band holds in 22 of them, and the line runs at Duchesne County (zone 6a), the coldest county still inside it.
Inside zones 6–10
22 counties
- Juab County · zone 6a
- Millard County · zone 6a
- Morgan County · zone 6a
3 of 22 shown
Below the zone 6 floor
7 counties
- Rich County · zone 4b
- Daggett County · zone 5b
- Iron County · zone 5b
3 of 7 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Even within Utah's zones 4a-9a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for black mustard (USDA PHZM 2023):
Zone Comparison
Black Mustard Needs
- USDA Zones: 6-10
- Frost-Free Days: 120+
- Sun: Full Sun
- Mature size: 4 ft tall
Utah Has
- USDA Zones: 4a-9a
- Last Hard Freeze (28°F): Apr 12 - May 6
- First Hard Freeze (28°F): Oct 8 - Oct 27
- Annual Rainfall: 5-20 inches
- Common Soils: Sandy loam, Alkaline clay, Desert sand
Plant Zone Range (zones 6-10)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Black Mustard in Utah
The frost window
Across Utah, the last spring hard freeze (28°F) clears between Apr 12 and May 6, and the first fall hard freeze lands between Oct 8 and Oct 27 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 155-day window you can count on — up to 198 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.
Days to maturity vs. the window
At 60 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 95 days to spare even in Utah's tightest freeze scenario — room for a later start or a second sowing.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. 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 black mustard survives winter in part of Utah, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Black Mustard wants 120+ frost-free days; a typical Utah site sees ~175 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
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
Black Mustard likes near-neutral soil (pH 5.3-7.8). That's the common-ground band across Utah's sandy loam and alkaline clay — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 7 — worth knowing before you decide whether a Utah soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Utah site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Utah soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Black Mustard in Utah
Zone compatibility tells you about winter cold survival — but Utah growers also need to think about:
Very low rainfall — irrigation essential
Alkaline soils (pH 7.5-8.5) limit many species
High altitude frost risk in mountain valleys
What to actually do about these — and the constraints that apply to every Utah grower, not just black mustard — is covered on the Utah growing guide.
Timing shifts within Utah
Black Mustard needs about 120 days of frost-free season to complete its cycle. 26 of Utah’s 29 counties give it that outright. The tightest that does is Sevier County at 136 frost-free days — 16 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Utah’s 29 counties the frost-free season runs from 98 days in Summit County to 237 days in Washington County — a spread of 139 days, which is why a single statewide planting date misleads. The median Utah county sees 175 frost-free days, leaving black mustard about 55 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"). Black Mustard's 120-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Black 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, black mustard can only work that bloom inside Utah's frost window — roughly 175 days, opening after the last 28°F freeze (Apr 12 - May 6) and closing at the first (Oct 8 - Oct 27), per NOAA Regional Climate Centers ACIS, 1991-2020.
Utah Cooperative Extension
For Utah-specific cultivar recommendations, planting calendars, and pest pressure for black mustard, the canonical source is Utah State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Black Mustard native to Utah?
No — the USDA PLANTS Database lists Black Mustard as introduced rather than native in the Lower 48, so it is not part of Utah's native flora. It grows here as a garden plant; pairing it with a few Utah natives keeps local pollinators fed too.
Looking for plants that belong here? The Utah 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 Black Mustard in Utah
When can I plant Black Mustard in Utah?
Utah's last spring hard freeze (28°F) clears between Apr 12 and May 6, and the first fall hard freeze lands between Oct 8 and Oct 27 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Black Mustard mature before first frost in Utah?
Yes — Black Mustard matures in 60 days (Growable Ground Plant Database), and Utah's dependable hard-freeze-free window runs 155 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 95 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 Black Mustard grown in across Utah?
Utah spans USDA hardiness zones 4a-9a (USDA ARS PHZM 2023). Black Mustard carries a range of zones 6-10, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Utah site have?
A typical Utah site sees ~175 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Black Mustard needs 120+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Black Mustard native to Utah?
No — the USDA PLANTS Database lists Black Mustard as introduced rather than native in the Lower 48, so it is not part of Utah's native flora. It grows here as a garden plant; pairing it with a few Utah natives keeps local pollinators fed too.
How should I amend the soil for Black Mustard in Utah?
Black Mustard prefers pH 5.3-7.8 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Utah soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Black Mustard actually grow on my specific land in Utah?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores black 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 Utah
State-level data is a sketch. Your Growable Ground report scores black mustard against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Utah black mustard averages can't show:
We read public map data around Utah — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Utah black mustard average
Explore More
Growing guides for black mustard
Explore Utah county by county
Utah carries 29 counties with their own USDA zone — a sample of the growing pages for black mustard there:
Where else black mustard grows
Black Mustard's zone band crosses state lines — these are the states closest to Utah in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Utah
Utah has a growing page for 1,038 plants — a rotating sample of the rest of the shelf.
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