USDA zone 8b in Arizona
USDA plant hardiness zone 8b covers 29 locations across Arizona (average annual extreme minimum 15 to 20 °F): Arivaca, AZ, Beyerville, AZ, Bisbee, AZ, Bowie, AZ, Camp Verde, AZ, Chloride, AZ, and 23 more. Average last spring frost across this group ranges January 5 (Chloride) to April 30 (Wilhoit), and growing seasons run 172–354 days (Wilhoit to Chloride) — 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 Rio Rico, this group's median-season location.
- USDA zone
- 8b15 to 20 °F
- Last frost range
- Jan 5–Apr 30avg, 32°F
- First frost range
- Oct 20–Dec 24avg, 32°F
- Growing season range
- 172–354days
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) |
|---|---|---|---|---|---|
| Arivaca | — | Sasabe | Mar 21 | Nov 20 | 246 |
| Beyerville | — | Nogales Intl Ap | Mar 20 | Nov 17 | 239 |
| Bisbee | Naco | Bisbee 1wnw | Apr 1 | Nov 10 | 222 |
| Bowie | — | Bowie | Apr 1 | Nov 6 | 217 |
| Camp Verde | Village of Oak Creek (Big Park) | Montezuma Castle Nm | Apr 16 | Oct 30 | 196 |
| Chloride | — | Laughlin | Jan 5 | Dec 24 | 354 |
| Cordes Lakes | — | Cordes | Apr 5 | Nov 17 | 221 |
| Cornville | Verde | Tuzigoot | Mar 30 | Nov 10 | 223 |
| Elfrida | Dragoon | Pearce - Sunsites | Apr 14 | Nov 2 | 200 |
| Fort Thomas | Bylas, Bryce | Ft Thomas 2 Sw | Apr 1 | Nov 6 | 217 |
| Jerome | — | Jerome | Mar 26 | Nov 25 | 242 |
| McNeal | — | Douglas Bisbee Inl Ap | Apr 11 | Nov 2 | 203 |
| Mescal | — | Cascabel | Apr 24 | Oct 31 | 187 |
| Morenci | — | Clifton | Feb 26 | Nov 23 | 268 |
| Payson | — | Payson | Apr 29 | Oct 24 | 176 |
| Peeples Valley | — | Wickenburg | Mar 7 | Nov 20 | 254 |
| Rio Rico * | Tubac, Amado, Tumacacori-Carmen | Tumacacori Nm | Apr 5 | Nov 10 | 217 |
| Sedona | — | Oak Creek Canyon | Apr 14 | Nov 5 | 204 |
| Sierra Vista | — | Elgin 5 S | Apr 18 | Nov 1 | 195 |
| Sierra Vista Southeast | — | Coronado Nmem | Apr 7 | Nov 9 | 213 |
| Sierra Vista Southeast | — | Sierra Vista | Apr 5 | Nov 9 | 216 |
| Thatcher | San Jose, Swift Trail Junction, Central | Safford Ag Ctr | Mar 25 | Nov 9 | 228 |
| Three Points | — | Anvil Rch | Mar 27 | Nov 9 | 226 |
| Tombstone | — | Tombstone | Mar 4 | Nov 29 | 264 |
| Valle Vista | Pine Lake | Kingman Mohave Co Ap | Apr 2 | Nov 11 | 220 |
| Whetstone | Benson, St. David, Dragoon | Benson 6se | Apr 12 | Nov 1 | 202 |
| Wilhoit | — | Prescott | Apr 30 | Oct 20 | 172 |
| Willcox | — | Willcox | Apr 9 | Oct 31 | 204 |
| Willow Canyon | — | Mt Lemmon Willow Canyon | Apr 1 | Nov 19 | 229 |
* Rio Rico 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 (Rio Rico, representative)
Computed from Rio Rico's average frost dates — the median-season location in this Arizonazone 8b 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 | Feb 8 – Feb 22 | Apr 12 – Apr 19 | Jun 11 – Jul 1 | — | matures comfortably |
| Pepper | Very tender | Jan 25 – Feb 8 | Apr 19 – Apr 26 | Jun 18 – Jul 18 | — | matures comfortably |
| Cucumber | Tender | Mar 8 – Mar 15 | Apr 12 – Apr 19 | Jun 1 – Jun 21 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Apr 12 – Apr 19 | May 27 – Jun 11 | — | matures comfortably |
| Bush bean | Tender | — | Apr 12 – Apr 19 | Jun 1 – Jun 11 | Sep 11 – Sep 21 | matures comfortably |
| Sweet corn | Tender | — | Apr 5 – Apr 19 | Jun 4 – Jul 4 | — | matures comfortably |
| Basil | Very tender | Feb 22 – Mar 8 | Apr 12 – Apr 19 | May 12 – May 27 | — | matures comfortably |
| Lettuce | Half-hardy | Feb 22 – Mar 8 | Mar 8 – Mar 22 | Apr 22 – May 7 | Aug 28 – Sep 12 | matures comfortably |
| Pea | Hardy | — | Feb 22 – Mar 8 | Apr 18 – May 3 | Aug 18 – Sep 2 | matures comfortably |
| Spinach | Hardy | — | Feb 22 – Mar 8 | Apr 3 – Apr 13 | Sep 7 – Sep 17 | matures comfortably |
| Carrot | Half-hardy | — | Mar 15 – Mar 22 | May 14 – Jun 3 | Aug 8 – Aug 28 | matures comfortably |
| Broccoli | Half-hardy | Feb 8 – Feb 22 | Mar 8 – Mar 22 | May 2 – May 22 | Aug 13 – Sep 2 | matures comfortably |
Which crops fit this growing season
Using Rio Rico's own 217-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 (Rio Rico)
From NOAA's 1991–2020 Climate Normals at station USC00028865. 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 | Apr 23 | May 9 | Oct 30 | Nov 14 | 190 |
| 32°F (freeze) | Apr 5 | Apr 25 | Nov 10 | Nov 27 | 217 |
| 28°F | Mar 12 | Apr 8 | Nov 20 | Dec 9 | 251 |
| 24°F | Feb 16 | Mar 11 | Dec 2 | Dec 26 | 286 |
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 29 locations is 5,195; Rio Rico's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 5,195 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 8,482 | cool-season crops (brassicas, greens) |
Hardiness zone 8b in Arizona
Zone 8b means an average annual extreme minimum winter temperature of about 15 to 20 °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, 7b, 8a, 9a, 9b, 10a.
Explore zone 8b in other states at zone 8b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 8b mean in Arizona?
- Zone 8b means an average annual extreme minimum winter temperature of 15 to 20 °F — the standard USDA measure of which perennials survive winter. 29 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 8b is the growing season longest?
- Chloride runs the longest season on this page at about 354 days; Wilhoit is shortest at about 172 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 8b?
- Using Rio Rico's frost dates (this page's median-season location): start seeds indoors about Feb 8 – Feb 22, then transplant outside about Apr 12 – Apr 19. 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 8b 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 29 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.