USDA zone 7a in Utah
USDA plant hardiness zone 7a covers 26 locations across Utah (average annual extreme minimum 0 to 5 °F): Boulder, UT, Enterprise, UT, Erda, UT, Escalante, UT, Grantsville, UT, Hanksville, UT, and 20 more. Average last spring frost across this group ranges April 11 (Spanish Valley) to June 2 (Saratoga Springs), and growing seasons run 103–192 days (Saratoga Springs to Spanish Valley) — 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 Erda, this group's median-season location.
- USDA zone
- 7a0 to 5 °F
- Last frost range
- Apr 11–Jun 2avg, 32°F
- First frost range
- Sep 16–Oct 28avg, 32°F
- Growing season range
- 103–192days
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) |
|---|---|---|---|---|---|
| Boulder | — | Boulder | May 4 | Oct 14 | 160 |
| Enterprise | — | Enterprise | May 21 | Oct 2 | 132 |
| Erda * | Herriman, Copperton metro | Tooele | May 2 | Oct 16 | 165 |
| Escalante | — | Escalante | May 8 | Oct 10 | 155 |
| Grantsville | — | Johnson Pass | May 15 | Oct 5 | 142 |
| Hanksville | — | Hanksville | May 5 | Oct 3 | 149 |
| Hanksville | — | Capitol Reef Np | Apr 18 | Oct 28 | 192 |
| Hildale | — | Colorado City | Apr 26 | Oct 25 | 180 |
| Kanab | — | Kanab | Apr 29 | Oct 22 | 175 |
| La Sal | — | La Sal 1sw | May 17 | Oct 6 | 141 |
| Layton | Plain, West Haven, Roy, West Point, Clinton, Sunset, +1 more | Ogden Hinkley Ap | Apr 22 | Oct 22 | 180 |
| Lehi | Draper, Riverton, Alpine | Alpine | May 3 | Oct 12 | 159 |
| Mapleton | Salem | Spanish Fk Pwr House | Apr 25 | Oct 18 | 174 |
| Modena | — | Modena | May 20 | Oct 3 | 136 |
| Montezuma Creek | — | Hovenweep Nm | May 2 | Oct 10 | 159 |
| New Harmony | — | New Harmony | May 9 | Oct 11 | 155 |
| Orderville | — | Orderville | May 15 | Oct 8 | 144 |
| Orem | Pleasant Grove, Lindon, Vineyard | Pleasant Grove | Apr 17 | Oct 25 | 188 |
| Provo | Orem | Provo Byu | Apr 18 | Oct 21 | 185 |
| Salt Lake | — | Bountiful-val Verda | Apr 24 | Oct 19 | 178 |
| Saratoga Springs | — | Fairfield | Jun 2 | Sep 16 | 103 |
| South Jordan | — | Cottonwood Weir | Apr 29 | Oct 22 | 174 |
| Spanish Valley | — | Moab | Apr 11 | Oct 23 | 192 |
| Tselakai Dezza | — | Bluff | Apr 24 | Oct 13 | 172 |
| White Mesa | — | Blanding | Apr 28 | Oct 21 | 174 |
| Willard | — | Brigham City Waste Plt | May 5 | Oct 5 | 150 |
* Erda 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 (Erda, representative)
Computed from Erda's average frost dates — the median-season location in this Utahzone 7a 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 7 – Mar 21 | May 9 – May 16 | Jul 8 – Jul 28 | — | matures comfortably |
| Pepper | Very tender | Feb 21 – Mar 7 | May 16 – May 23 | Jul 15 – Aug 14 | — | matures comfortably |
| Cucumber | Tender | Apr 4 – Apr 11 | May 9 – May 16 | Jun 28 – Jul 18 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 9 – May 16 | Jun 23 – Jul 8 | — | matures comfortably |
| Bush bean | Tender | — | May 9 – May 16 | Jun 28 – Jul 8 | Aug 17 – Aug 27 | matures comfortably |
| Sweet corn | Tender | — | May 2 – May 16 | Jul 1 – Jul 31 | — | matures comfortably |
| Basil | Very tender | Mar 21 – Apr 4 | May 9 – May 16 | Jun 8 – Jun 23 | — | matures comfortably |
| Lettuce | Half-hardy | Mar 21 – Apr 4 | Apr 4 – Apr 18 | May 19 – Jun 3 | Aug 3 – Aug 18 | matures comfortably |
| Pea | Hardy | — | Mar 21 – Apr 4 | May 15 – May 30 | Jul 24 – Aug 8 | matures comfortably |
| Spinach | Hardy | — | Mar 21 – Apr 4 | Apr 30 – May 10 | Aug 13 – Aug 23 | matures comfortably |
| Carrot | Half-hardy | — | Apr 11 – Apr 18 | Jun 10 – Jun 30 | Jul 14 – Aug 3 | matures comfortably |
| Broccoli | Half-hardy | Mar 7 – Mar 21 | Apr 4 – Apr 18 | May 29 – Jun 18 | Jul 19 – Aug 8 | matures comfortably |
Which crops fit this growing season
Using Erda's own 165-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 (Erda)
From NOAA's 1991–2020 Climate Normals at station USC00428771. 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 16 | Jun 6 | Oct 6 | Oct 19 | 141 |
| 32°F (freeze) | May 2 | May 28 | Oct 16 | Nov 2 | 165 |
| 28°F | Apr 16 | May 7 | Oct 27 | Nov 12 | 193 |
| 24°F | Mar 26 | Apr 15 | Nov 8 | Nov 22 | 225 |
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 26 locations is 3,200; Erda's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 3,287 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 5,492 | cool-season crops (brassicas, greens) |
Hardiness zone 7a in Utah
Zone 7a means an average annual extreme minimum winter temperature of about 0 to 5 °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, 6b, 7b, 8a, 8b.
Explore zone 7a in other states at zone 7a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 7a mean in Utah?
- Zone 7a means an average annual extreme minimum winter temperature of 0 to 5 °F — the standard USDA measure of which perennials survive winter. 26 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 7a is the growing season longest?
- Spanish Valley runs the longest season on this page at about 192 days; Saratoga Springs is shortest at about 103 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 7a?
- Using Erda's frost dates (this page's median-season location): start seeds indoors about Mar 7 – Mar 21, then transplant outside about May 9 – May 16. 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 7a 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 26 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.