USDA zone 6b in Utah
USDA plant hardiness zone 6b covers 37 locations across Utah (average annual extreme minimum −5 to 0 °F): Castle Valley, UT, Eagle Mountain, UT, East Carbon, UT, Emery, UT, Emigration Canyon metro, UT, Emigration Canyon metro, UT, and 31 more. Average last spring frost across this group ranges April 13 (La Verkin) to June 14 (Wendover), and growing seasons run 86–202 days (Wendover to La Verkin) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Utah location's own frost dates; the printable planting calendar uses Ferron, this group's median-season location.
- USDA zone
- 6b−5 to 0 °F
- Last frost range
- Apr 13–Jun 14avg, 32°F
- First frost range
- Sep 8–Nov 2avg, 32°F
- Growing season range
- 86–202days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Castle Valley | — | Gateway 1ene | Apr 20 | Oct 21 | 182 |
| Eagle Mountain | Ophir | Fairfield | Jun 2 | Sep 16 | 103 |
| East Carbon | — | Sunnyside City | Apr 26 | Oct 25 | 181 |
| Emery | — | Salina 24 E | May 29 | Sep 26 | 118 |
| Emigration Canyon metro | Bountiful, Centerville | Bountiful Bench | Apr 25 | Oct 24 | 181 |
| Emigration Canyon metro | — | Cottonwood Weir | Apr 29 | Oct 22 | 174 |
| Enoch | — | Cedar City Muni Ap | May 21 | Sep 29 | 130 |
| Escalante | — | Escalante | May 8 | Oct 10 | 155 |
| Eureka | — | Little Sahara Rec Area | May 15 | Oct 1 | 137 |
| Fayette | — | Manti | May 11 | Oct 6 | 146 |
| Ferron * | — | Ferron | May 6 | Oct 10 | 156 |
| Granite | — | Alta | Jun 11 | Sep 18 | 98 |
| Green River | Thompson Springs | Moab Canyonland Ap | Apr 22 | Oct 20 | 179 |
| Hobble Creek | Sundance | Provo Byu | Apr 18 | Oct 21 | 185 |
| Honeyville | Bear River | Brigham City Waste Plt | May 5 | Oct 5 | 150 |
| Kanosh | — | Fremont Indian Sp | Jun 4 | Sep 21 | 106 |
| Kenilworth | — | Price Carbon Co Ap | May 3 | Oct 12 | 160 |
| La Sal | Nucla | Uravan | Apr 26 | Oct 18 | 174 |
| La Verkin | Springdale | Zion Np | Apr 13 | Nov 2 | 202 |
| Meadow | — | Fillmore | May 4 | Oct 14 | 160 |
| Monticello | — | Monticello 2e | May 19 | Oct 2 | 133 |
| Oak | — | Oak City | May 2 | Oct 13 | 162 |
| Ogden | North Ogden | Pineview Dam | May 22 | Sep 26 | 125 |
| Ogden | — | Ogden Hinkley Ap | Apr 22 | Oct 22 | 180 |
| Orderville | Glendale | Orderville | May 15 | Oct 8 | 144 |
| Pine Valley | Central, Kanarraville | New Harmony | May 9 | Oct 11 | 155 |
| Riverside | — | Cutler Dam | May 3 | Oct 12 | 160 |
| Rush Valley | — | Johnson Pass | May 15 | Oct 5 | 142 |
| Salt Lake | — | Bountiful-val Verda | Apr 24 | Oct 19 | 178 |
| Santaquin | Elk Ridge, Mona, Elberta, Goshen | Santaquin Chlorinator | May 4 | Oct 11 | 157 |
| Summit | — | Cedar City 5e | May 23 | Oct 4 | 130 |
| Thatcher | — | Brigham City 28 Wnw | May 12 | Oct 5 | 144 |
| Thatcher | Deweyville | Tremonton | Apr 24 | Oct 17 | 175 |
| Thompson Springs | — | Dewey | Apr 27 | Oct 9 | 165 |
| Vernon | — | Vernon | Jun 1 | Sep 20 | 110 |
| Wendover | — | Ibapah | Jun 14 | Sep 8 | 86 |
| Wendover | West Wendover | Wendover Ap Awos | Apr 18 | Oct 23 | 188 |
* Ferron is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Ferron, representative)
Computed from Ferron's average frost dates — the median-season location in this Utahzone 6b group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Mar 11 – Mar 25 | May 13 – May 20 | Jul 12 – Aug 1 | — | matures comfortably |
| Pepper | Very tender | Feb 25 – Mar 11 | May 20 – May 27 | Jul 19 – Aug 18 | — | matures comfortably |
| Cucumber | Tender | Apr 8 – Apr 15 | May 13 – May 20 | Jul 2 – Jul 22 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 13 – May 20 | Jun 27 – Jul 12 | — | matures comfortably |
| Bush bean | Tender | — | May 13 – May 20 | Jul 2 – Jul 12 | Aug 11 – Aug 21 | matures comfortably |
| Sweet corn | Tender | — | May 6 – May 20 | Jul 5 – Aug 4 | — | matures comfortably |
| Basil | Very tender | Mar 25 – Apr 8 | May 13 – May 20 | Jun 12 – Jun 27 | — | matures comfortably |
| Lettuce | Half-hardy | Mar 25 – Apr 8 | Apr 8 – Apr 22 | May 23 – Jun 7 | Jul 28 – Aug 12 | matures comfortably |
| Pea | Hardy | — | Mar 25 – Apr 8 | May 19 – Jun 3 | Jul 18 – Aug 2 | matures comfortably |
| Spinach | Hardy | — | Mar 25 – Apr 8 | May 4 – May 14 | Aug 7 – Aug 17 | matures comfortably |
| Carrot | Half-hardy | — | Apr 15 – Apr 22 | Jun 14 – Jul 4 | Jul 8 – Jul 28 | matures comfortably |
| Broccoli | Half-hardy | Mar 11 – Mar 25 | Apr 8 – Apr 22 | Jun 2 – Jun 22 | Jul 13 – Aug 2 | matures comfortably |
Which crops fit this growing season
Using Ferron's own 156-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Ferron)
From NOAA's 1991–2020 Climate Normals at station USC00422798. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | May 21 | Jun 9 | Oct 1 | Oct 13 | 131 |
| 32°F (freeze) | May 6 | May 27 | Oct 10 | Oct 22 | 156 |
| 28°F | Apr 23 | May 11 | Oct 19 | Nov 4 | 177 |
| 24°F | Apr 8 | Apr 26 | Oct 31 | Nov 13 | 204 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 37 locations is 2,837; Ferron's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,871 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,960 | cool-season crops (brassicas, greens) |
Hardiness zone 6b in Utah
Zone 6b means an average annual extreme minimum winter temperature of about −5 to 0 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Utah spans 9 hardiness zones in this dataset — see all Utah locations for the full range, including zones4a, 5a, 5b, 6a, 7a, 7b, 8a, 8b.
Explore zone 6b in other states at zone 6b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 6b mean in Utah?
- Zone 6b means an average annual extreme minimum winter temperature of −5 to 0 °F — the standard USDA measure of which perennials survive winter. 37 locations in Utah fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Utah's zone 6b is the growing season longest?
- La Verkin runs the longest season on this page at about 202 days; Wendover is shortest at about 86 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in Utah's zone 6b?
- Using Ferron's frost dates (this page's median-season location): start seeds indoors about Mar 11 – Mar 25, then transplant outside about May 13 – May 20. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in Utah's zone 6b have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 37 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.