USDA zone 7b in Arizona
USDA plant hardiness zone 7b covers 6 locations across Arizona (average annual extreme minimum 5 to 10 °F): Cameron, AZ, Colorado, AZ, Fort Apache, AZ, LeChee, AZ, Prescott, AZ, Williamson, AZ. Average last spring frost across this group ranges March 27 (LeChee) to May 24 (Williamson), and growing seasons run 135–226 days (Williamson to LeChee) — 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 Colorado, this group's median-season location.
- USDA zone
- 7b5 to 10 °F
- Last frost range
- Mar 27–May 24avg, 32°F
- First frost range
- Oct 7–Nov 9avg, 32°F
- Growing season range
- 135–226days
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) |
|---|---|---|---|---|---|
| Cameron | Moenkopi | Tuba City | Apr 16 | Oct 28 | 193 |
| Colorado * | — | Colorado City | Apr 26 | Oct 25 | 180 |
| Fort Apache | — | Mc Nary 2n | May 20 | Oct 11 | 142 |
| LeChee | Kaibito, Bitter Springs | Page | Mar 27 | Nov 9 | 226 |
| Prescott | Prescott Valley | Prescott | Apr 30 | Oct 20 | 172 |
| Williamson | — | Walnut Creek | May 24 | Oct 7 | 135 |
* Colorado 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 (Colorado, representative)
Computed from Colorado's average frost dates — the median-season location in this Arizonazone 7b 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 1 – Mar 15 | May 3 – May 10 | Jul 2 – Jul 22 | — | matures comfortably |
| Pepper | Very tender | Feb 15 – Mar 1 | May 10 – May 17 | Jul 9 – Aug 8 | — | matures comfortably |
| Cucumber | Tender | Mar 29 – Apr 5 | May 3 – May 10 | Jun 22 – Jul 12 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 3 – May 10 | Jun 17 – Jul 2 | — | matures comfortably |
| Bush bean | Tender | — | May 3 – May 10 | Jun 22 – Jul 2 | Aug 26 – Sep 5 | matures comfortably |
| Sweet corn | Tender | — | Apr 26 – May 10 | Jun 25 – Jul 25 | — | matures comfortably |
| Basil | Very tender | Mar 15 – Mar 29 | May 3 – May 10 | Jun 2 – Jun 17 | — | matures comfortably |
| Lettuce | Half-hardy | Mar 15 – Mar 29 | Mar 29 – Apr 12 | May 13 – May 28 | Aug 12 – Aug 27 | matures comfortably |
| Pea | Hardy | — | Mar 15 – Mar 29 | May 9 – May 24 | Aug 2 – Aug 17 | matures comfortably |
| Spinach | Hardy | — | Mar 15 – Mar 29 | Apr 24 – May 4 | Aug 22 – Sep 1 | matures comfortably |
| Carrot | Half-hardy | — | Apr 5 – Apr 12 | Jun 4 – Jun 24 | Jul 23 – Aug 12 | matures comfortably |
| Broccoli | Half-hardy | Mar 1 – Mar 15 | Mar 29 – Apr 12 | May 23 – Jun 12 | Jul 28 – Aug 17 | matures comfortably |
Which crops fit this growing season
Using Colorado's own 180-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 (Colorado)
From NOAA's 1991–2020 Climate Normals at station USC00021920. 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 8 | May 31 | Oct 15 | Oct 29 | 157 |
| 32°F (freeze) | Apr 26 | May 15 | Oct 25 | Nov 9 | 180 |
| 28°F | Apr 10 | May 2 | Nov 5 | Nov 19 | 206 |
| 24°F | Mar 17 | Apr 12 | Nov 15 | Nov 29 | 241 |
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 6 locations is 3,618; Colorado's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 3,812 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 6,351 | cool-season crops (brassicas, greens) |
Hardiness zone 7b in Arizona
Zone 7b means an average annual extreme minimum winter temperature of about 5 to 10 °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, 6b, 7a, 8a, 8b, 9a, 9b, 10a.
Explore zone 7b in other states at zone 7b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 7b mean in Arizona?
- Zone 7b means an average annual extreme minimum winter temperature of 5 to 10 °F — the standard USDA measure of which perennials survive winter. 6 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 7b is the growing season longest?
- LeChee runs the longest season on this page at about 226 days; Williamson is shortest at about 135 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 7b?
- Using Colorado's frost dates (this page's median-season location): start seeds indoors about Mar 1 – Mar 15, then transplant outside about May 3 – May 10. 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 7b 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 6 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.