USDA zone 6b in Arizona
USDA plant hardiness zone 6b covers 18 locations across Arizona (average annual extreme minimum −5 to 0 °F): Alpine, AZ, Cameron, AZ, Christopher Creek, AZ, Clay Springs, AZ, Cornfields, AZ, Grand Canyon, AZ, and 12 more. Average last spring frost across this group ranges April 7 (Cameron) to June 16 (Timberline-Fernwood), and growing seasons run 94–206 days (Timberline-Fernwood to Cameron) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Arizona location's own frost dates; the printable planting calendar uses Cornfields, this group's median-season location.
- USDA zone
- 6b−5 to 0 °F
- Last frost range
- Apr 7–Jun 16avg, 32°F
- First frost range
- Sep 19–Nov 3avg, 32°F
- Growing season range
- 94–206days
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) |
|---|---|---|---|---|---|
| Alpine | Nutrioso | Alpine | Jun 15 | Sep 21 | 96 |
| Cameron | — | Wupatki Nm | Apr 7 | Nov 3 | 206 |
| Christopher Creek | — | Pleasant Valley | May 6 | Oct 20 | 165 |
| Clay Springs | — | Snowflake | May 11 | Oct 10 | 149 |
| Cornfields * | — | Ganado | May 15 | Oct 10 | 147 |
| Grand Canyon | — | Bright Angel Rs | Jun 3 | Sep 27 | 113 |
| Heber-Overgaard | — | Heber (black Mesa) Rs | May 23 | Oct 5 | 135 |
| Houck | Sanders, Lupton | Sanders | May 22 | Oct 8 | 138 |
| Jeddito | — | Keams Canyon | May 16 | Oct 10 | 147 |
| Mormon Lake | — | Mund's Park | Jun 10 | Sep 27 | 106 |
| Nazlini | Crystal | Canyon De Chelly | May 6 | Oct 8 | 153 |
| Parks | — | Williams | May 22 | Oct 5 | 135 |
| Pinetop-Lakeside | Pinedale | Show Low Ap | May 5 | Oct 15 | 162 |
| Pinetop-Lakeside | McNary, Vernon | Mc Nary 2n | May 20 | Oct 11 | 142 |
| Pinon | — | Betatakin | May 7 | Oct 15 | 159 |
| Springerville | — | Springerville | Jun 1 | Sep 26 | 114 |
| St. Johns | — | St Johns Industrial Ap | May 3 | Oct 10 | 160 |
| Timberline-Fernwood | — | Sunset Crater Nm | Jun 16 | Sep 19 | 94 |
* Cornfields 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 (Cornfields, representative)
Computed from Cornfields's average frost dates — the median-season location in this Arizonazone 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 20 – Apr 3 | May 22 – May 29 | Jul 21 – Aug 10 | — | matures comfortably |
| Pepper | Very tender | Mar 6 – Mar 20 | May 29 – Jun 5 | Jul 28 – Aug 27 | — | matures comfortably |
| Cucumber | Tender | Apr 17 – Apr 24 | May 22 – May 29 | Jul 11 – Jul 31 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 22 – May 29 | Jul 6 – Jul 21 | — | matures comfortably |
| Bush bean | Tender | — | May 22 – May 29 | Jul 11 – Jul 21 | Aug 11 – Aug 21 | matures comfortably |
| Sweet corn | Tender | — | May 15 – May 29 | Jul 14 – Aug 13 | — | matures comfortably |
| Basil | Very tender | Apr 3 – Apr 17 | May 22 – May 29 | Jun 21 – Jul 6 | — | matures comfortably |
| Lettuce | Half-hardy | Apr 3 – Apr 17 | Apr 17 – May 1 | Jun 1 – Jun 16 | Jul 28 – Aug 12 | matures comfortably |
| Pea | Hardy | — | Apr 3 – Apr 17 | May 28 – Jun 12 | Jul 18 – Aug 2 | matures comfortably |
| Spinach | Hardy | — | Apr 3 – Apr 17 | May 13 – May 23 | Aug 7 – Aug 17 | matures comfortably |
| Carrot | Half-hardy | — | Apr 24 – May 1 | Jun 23 – Jul 13 | Jul 8 – Jul 28 | matures comfortably |
| Broccoli | Half-hardy | Mar 20 – Apr 3 | Apr 17 – May 1 | Jun 11 – Jul 1 | Jul 13 – Aug 2 | matures comfortably |
Which crops fit this growing season
Using Cornfields's own 147-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 (Cornfields)
From NOAA's 1991–2020 Climate Normals at station USC00023303. 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 29 | Jun 14 | Oct 1 | Oct 15 | 126 |
| 32°F (freeze) | May 15 | Jun 1 | Oct 10 | Oct 24 | 147 |
| 28°F | May 2 | May 21 | Oct 19 | Nov 3 | 167 |
| 24°F | Apr 21 | May 7 | Oct 29 | Nov 11 | 188 |
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 18 locations is 2,683; Cornfields's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,719 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,919 | cool-season crops (brassicas, greens) |
Hardiness zone 6b in Arizona
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. Arizona spans 10 hardiness zones in this dataset — see all Arizona locations for the full range, including zones5b, 6a, 7a, 7b, 8a, 8b, 9a, 9b, 10a.
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 Arizona?
- Zone 6b means an average annual extreme minimum winter temperature of −5 to 0 °F — the standard USDA measure of which perennials survive winter. 18 locations in Arizona fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Arizona's zone 6b is the growing season longest?
- Cameron runs the longest season on this page at about 206 days; Timberline-Fernwood is shortest at about 94 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 Arizona's zone 6b?
- Using Cornfields's frost dates (this page's median-season location): start seeds indoors about Mar 20 – Apr 3, then transplant outside about May 22 – May 29. 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 Arizona'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 18 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.