USDA zone 5a in Utah
USDA plant hardiness zone 5a covers 3 locations across Utah (average annual extreme minimum −20 to −15 °F): Garden, UT, Tabiona, UT, Woodruff, UT. Average last spring frost across this group ranges May 28 (Garden) to June 11 (Tabiona), and growing seasons run 97–119 days (Tabiona to Garden) — 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 Woodruff, this group's median-season location.
- USDA zone
- 5a−20 to −15 °F
- Last frost range
- May 28–Jun 11avg, 32°F
- First frost range
- Sep 18–Sep 25avg, 32°F
- Growing season range
- 97–119days
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) |
|---|---|---|---|---|---|
| Garden | — | Laketown | May 28 | Sep 24 | 119 |
| Tabiona | — | Moon Lake | Jun 11 | Sep 18 | 97 |
| Woodruff * | — | Evanston Burns Fld | Jun 3 | Sep 25 | 113 |
* Woodruff 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 (Woodruff, representative)
Computed from Woodruff's average frost dates — the median-season location in this Utahzone 5a 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 | Apr 8 – Apr 22 | Jun 10 – Jun 17 | Aug 9 – Aug 29 | — | matures comfortably |
| Pepper | Very tender | Mar 25 – Apr 8 | Jun 17 – Jun 24 | Aug 16 – Sep 15 | — | matures, but with little margin |
| Cucumber | Tender | May 6 – May 13 | Jun 10 – Jun 17 | Jul 30 – Aug 19 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Jun 10 – Jun 17 | Jul 25 – Aug 9 | — | matures comfortably |
| Bush bean | Tender | — | Jun 10 – Jun 17 | Jul 30 – Aug 9 | Jul 27 – Aug 6 | matures comfortably |
| Sweet corn | Tender | — | Jun 3 – Jun 17 | Aug 2 – Sep 1 | — | matures comfortably |
| Basil | Very tender | Apr 22 – May 6 | Jun 10 – Jun 17 | Jul 10 – Jul 25 | — | matures comfortably |
| Lettuce | Half-hardy | Apr 22 – May 6 | May 6 – May 20 | Jun 20 – Jul 5 | Jul 13 – Jul 28 | matures comfortably |
| Pea | Hardy | — | Apr 22 – May 6 | Jun 16 – Jul 1 | Jul 3 – Jul 18 | matures comfortably |
| Spinach | Hardy | — | Apr 22 – May 6 | Jun 1 – Jun 11 | Jul 23 – Aug 2 | matures comfortably |
| Carrot | Half-hardy | — | May 13 – May 20 | Jul 12 – Aug 1 | Jun 23 – Jul 13 | matures comfortably |
| Broccoli | Half-hardy | Apr 8 – Apr 22 | May 6 – May 20 | Jun 30 – Jul 20 | Jun 28 – Jul 18 | matures comfortably |
Which crops fit this growing season
Using Woodruff's own 113-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 11 of 12 crops mature here with comfortable margin, 1matures with little room to spare. The tightest fits: pepper (+10 day 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 (Woodruff)
From NOAA's 1991–2020 Climate Normals at station USW00004111. 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 | Jun 13 | Jun 24 | Sep 16 | Sep 26 | 92 |
| 32°F (freeze) | Jun 3 | Jun 17 | Sep 25 | Oct 8 | 113 |
| 28°F | May 17 | Jun 6 | Oct 4 | Oct 21 | 138 |
| 24°F | May 2 | May 20 | Oct 17 | Oct 31 | 165 |
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 3 locations is 1,550; Woodruff's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 1,663 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 3,312 | cool-season crops (brassicas, greens) |
Hardiness zone 5a in Utah
Zone 5a means an average annual extreme minimum winter temperature of about −20 to −15 °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, 5b, 6a, 6b, 7a, 7b, 8a, 8b.
Explore zone 5a in other states at zone 5a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 5a mean in Utah?
- Zone 5a means an average annual extreme minimum winter temperature of −20 to −15 °F — the standard USDA measure of which perennials survive winter. 3 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 5a is the growing season longest?
- Garden runs the longest season on this page at about 119 days; Tabiona is shortest at about 97 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 5a?
- Using Woodruff's frost dates (this page's median-season location): start seeds indoors about Apr 8 – Apr 22, then transplant outside about Jun 10 – Jun 17. 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 5a 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 3 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.