Generally — Most Areas
thyme (zones 5-9) suits most of Utah (4a-9a) — zones 5-9 are in range, and the rest of the state is the exception.
Thyme in Utah — the short answer
Thyme in Utah: hardy in zones 5–9, full sun.
- Plant zones
- 5-9
- NC State Extension Gardener Plant Toolbox
- 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
- 85 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 thyme 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 thyme 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
Thyme is rated for zones 5–9 — a cold floor USDA puts at -20 to -10°F. Against Utah’s 29 counties that band holds in 28 of them, and the line runs at Daggett County (zone 5b), the coldest county still inside it.
Inside zones 5–9
28 counties
- Iron County · zone 5b
- Sanpete County · zone 5b
- Summit County · zone 5b
3 of 28 shown
Below the zone 5 floor
1 county
- Rich County · zone 4b
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 thyme (USDA PHZM 2023):
Zone Comparison
Thyme Needs
- USDA Zones: 5-9
- Sun: Full Sun
- Mature size: 1 ft tall
- Picking window: ~120 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 5-9)
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 Thyme 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.
When to start the seed
Those dates are when thyme goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from Utah's late-side last freeze of May 6 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Winter standing
Thyme overwinters from USDA zone 5 and warmer (NC State Extension Gardener Plant Toolbox), and Utah runs as cold as zone 4, so it does not survive winter in the ground here. It is a woody plant rather than a crop you resow each spring, so neither a fall establishment date nor a harvest countdown describes it in Utah — which is why this page gives neither. What it needs here is a way through winter, not a planting date.
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 thyme 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
Thyme needs ~2000 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
Thyme tolerates a wide pH range (pH 4.5-8) — 3.5 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 5.5 and 6.5 — 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), excessive (dry/moderately dry). 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.
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 thyme 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 thyme 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 Thyme 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 thyme — is covered on the Utah growing guide.
Where in Utah Thyme Is Zone-Hardy
Thyme is rated for USDA zones 5–9. 28 of Utah’s 29 counties fall inside that band. The coldest that does is Daggett County at zone 5b. 1 county sits below the plant’s zone 5 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 thyme 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". Thyme’s zone 5–9 band: NC State Extension Gardener Plant Toolbox. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Thyme draws honeybees, native bees, and butterflies (high value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, thyme 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. Deer pressure is meaningful across much of Utah; thyme is listed as deer-resistant (NC State Extension Gardener Plant Toolbox), which makes it a safer pick for unfenced sites. Our deer & wildlife guide carries the full deer-resistant list and how to protect the rest. Pollinator value: We haven't confirmed this against a published source yet.
Good to Know Before You Plant Thyme
Listed as non-toxic to dogs and cats by a source we can't cite. We haven't confirmed this against a published source yet.
Utah Cooperative Extension
For Utah-specific cultivar recommendations, planting calendars, and pest pressure for thyme, the canonical source is Utah State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Thyme native to Utah?
No — the USDA PLANTS Database lists Thyme 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 Thyme in Utah
When can I plant Thyme 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). Thyme overwinters only from USDA zone 5 and warmer, and Utah runs as cold as zone 4, so it does not survive winter in the ground here — the question for Utah growers is how to carry it through winter under cover, not which week to plant it.
What hardiness zone is Thyme grown in across Utah?
Utah spans USDA hardiness zones 4a-9a (USDA ARS PHZM 2023). Thyme carries a range of zones 5-9, 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). Thyme needs 100+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Thyme native to Utah?
No — the USDA PLANTS Database lists Thyme 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 Thyme in Utah?
Thyme tolerates pH 4.5-8 and well (dry spells), excessive (dry/moderately dry) drainage (FAO ECOCROP). That is a 3.5-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 Thyme actually grow on my specific land in Utah?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores thyme 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 thyme against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Utah thyme 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 thyme average
Explore More
Growing guides for thyme
Explore Utah county by county
Utah carries 29 counties with their own USDA zone — a sample of the growing pages for thyme there:
Where else thyme grows
Thyme'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.
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