Generally — Most Areas
saffron crocus (zones 6-9) suits most of Utah (4a-9a) — zones 6-9 are in range, and the rest of the state is the exception.
Saffron Crocus in Utah — the short answer
Saffron Crocus in Utah: hardy in zones 6–9, full sun.
- Plant zones
- 6-9
- Not verified — NC State Extension Gardener Plant Toolbox lists zones 5a–8b
- 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
- 75 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.
Utah spans zones 4a-9a, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score saffron crocus against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your parcel report in seconds — read in full free for your first 14 days
Utah is not one climate
Utah’s winter-low ladder runs across 29 counties, from zone 4.5 in Rich County to zone 7.5 in Washington County. That is 30°F between the two counties’ average coldest night — the difference between saffron crocus overwintering in the ground and coming under cover.
The middle half of 29 counties runs 6–7 zones, with a median of 6.5 zones — a 3-zone span end to end.
Measured across 29 Utah counties. USDA PHZM 2023, per county. 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
Saffron Crocus is rated for zones 6–9 — 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 6–9
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 saffron crocus (USDA PHZM 2023):
Zone Comparison
Saffron Crocus Needs
- USDA Zones: 6-9
- Sun: Full Sun
- Mature size: 6 in tallWe haven't confirmed this against a published source yet.
- Picking window: ~7 days of harvestWe haven't confirmed this against a published source yet.
- Drought tolerance: HighWe haven't confirmed this against a published source yet.
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 6-9)
Preferred Soil pH
We haven't confirmed this against a published source yet.
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 Saffron Crocus 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.
Winter standing
Utah runs as cold as USDA zone 4, and no sourced winter-hardiness floor is on record for saffron crocus, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether saffron crocus is a permanent planting or a replant-every-spring crop for you turns on your own zone within Utah; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Summit County, not the statewide average.
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 saffron crocus survives winter in part of Utah, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Growing degree days
Saffron Crocus needs ~1500 GDD (base 50°F) to ripen. We haven't confirmed this against a published source yet. The state median runs ~2690 GDD (from PRISM 1991-2020 climate normals), so Utah'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
Saffron Crocus tolerates a wide pH range (pH 5.5-8.5) — 3 units, acid ground through alkaline — so soil acidity is rarely what limits it in Utah. 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 6 and 8 — 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, a raised bed lifts the roots above wet ground, or work in compost. pH range, preferred pH and drainage need: We haven't confirmed this against a published source yet.
Your land, not the state average
Utah's soils run mostly loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for saffron crocus is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how saffron crocus performs.
Check your parcel → Source: USDA NRCS SSURGO.
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.
Before you plant saffron crocus for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before saffron crocus goes in. What follows is Utah’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Utah — and how to grow with it.
We checked the federal record across Utah — 11,221 documented sites across 7 of the 8 source types we track.
The most significant on record: 202 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Utah carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds of imported, lab-tested soil grow well almost anywhere in the meantime.
Sources Checked
across Utah
Severity Distribution
across Utah
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Utah, Mining runs higher than the national average — 3,654 sites across Utah. That's not a problem with your land — it's information about it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Sources: EPA, USGS — 950K documented sites tracked nationwide across 8 federal source types.
What Else to Consider for Saffron Crocus 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
Growing saffron crocus here specifically
Utah's soils run mostly loam (Mollisols), and whether that suits saffron crocus's pH 5.5–8.5 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward saffron crocus's 5.5–8.5 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Utah grower, not just saffron crocus — is covered on the Utah growing guide.
Timing shifts within Utah
Utah isn't one climate. In Summit County, the last hard freeze (28°F) holds until about Jun 10 — roughly 45 days later than the recorded state median — so plant saffron crocus to your county's window, not the statewide date.
County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). A parcel report resolves your address's own frost dates.
Where in Utah Saffron Crocus Is Zone-Hardy
Saffron Crocus is rated for USDA zones 6–9. 22 of Utah’s 29 counties fall inside that band. The coldest that does is Duchesne County at zone 6a. 7 counties sit below the plant’s zone 6 floor, where an unprotected plant is relying on snow cover and a mild year. Where you are in Utah decides this one.
Across those 29 counties Utah’s winter-low ladder runs from zone 4b in Rich County to zone 7b in Washington County — 3 USDA zones of spread, which is 30°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Summit County holds its last hard freeze (28°F) until about Jun 10, while Washington County is clear by Mar 20 — 82 days apart. Set saffron crocus out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Saffron Crocus’s zone 6–9 band: Not verified — NC State Extension Gardener Plant Toolbox lists zones 5a–8b. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Saffron Crocus draws honeybees and native bees (moderate value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, saffron crocus 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. Pollinator value: We haven't confirmed this against a published source yet.
Good to Know Before You Plant Saffron Crocus
Saffron Crocus is listed as toxic to dogs, cats. (Source: Pet Poison Helpline.) Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
On Growable Ground, Saffron Crocus means Crocus sativus — not to be confused with autumn crocus (Colchicum autumnale). a different plant that is very toxic to pets; if you cannot tell which one a pet ate, treat it as autumn crocus.
Recommended Saffron Crocus Varieties for Utah
Utah publishes no state variety trial for saffron crocus, so we won't invent a "best for Utah" list. Choose types rated to your USDA hardiness zone (4a-9a), and confirm winter survival and drainage against your own parcel.
Utah Cooperative Extension
For Utah-specific cultivar recommendations, planting calendars, and pest pressure for saffron crocus, the canonical source is Utah State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Saffron Crocus native to Utah?
No — the USDA PLANTS Database lists Saffron Crocus 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 plants that USDA PLANTS records growing in Utah and that Kew and NatureServe Explorer both list in its native range, leaving out any that NatureServe flags as exotic there or that our audit holds.
State records: USDA PLANTS Database state-distribution data (presence, not state-level nativity), accessed 2026-10-19.
Common Questions About Growing Saffron Crocus in Utah
When can I plant Saffron Crocus 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). No sourced winter-hardiness floor is on record for Saffron Crocus, so this page does not state whether it overwinters in Utah and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Saffron Crocus grown in across Utah?
Utah spans USDA hardiness zones 4a-9a (USDA ARS PHZM 2023). Saffron Crocus carries a range of zones 6-9, 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). Saffron Crocus needs 150+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Summit, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Saffron Crocus native to Utah?
No — the USDA PLANTS Database lists Saffron Crocus 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 Saffron Crocus in Utah?
Saffron Crocus tolerates pH 5.5-8.5 and well (dry spells) drainage. We haven't confirmed this against a published source yet. That is a 3-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Utah site — amend for drainage and organic matter first.
Will Saffron Crocus actually grow on my specific land in Utah?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores saffron crocus against your address's mapped 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 saffron crocus against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Utah saffron crocus 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 saffron crocus average
Explore More
Growing guides for saffron crocus
Explore Utah county by county
Utah carries 29 counties with their own USDA zone — a sample of the growing pages for saffron crocus there:
Where else saffron crocus grows
Saffron Crocus'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 1,033 plants — a rotating sample of the rest of the shelf.
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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