Tucson, AZ 85730 planting calendar
- USDA zone
- 9a20 to 25 °F
- Last frost
- Jan 26avg, 32°F
- First frost
- Dec 16avg, 32°F
- Growing season
- 326days
Tucson, Arizona is in USDA plant hardiness zone 9a. Its average last spring frost is around January 26 and the first fall frost around December 16, giving a growing season of about 326 days (NOAA 1991–2020 normals, 32°F, median). Start tender crops like tomatoes and peppers indoors weeks before the last frost and set them out afterward; sow hardy crops such as peas, spinach, and lettuce before it. The planner below turns those frost dates into a printable per-crop planting calendar.
Tucson planting calendar
Each crop's windows are counted from Tucson's average frost dates. 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.
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting |
|---|---|---|---|---|---|
| Tomato | Tender | Jan 1 | Feb 2 – Feb 9 | Apr 3 – Apr 23 | — |
| Pepper | Very tender | Jan 1 | Feb 9 – Feb 16 | Apr 10 – May 10 | — |
| Cucumber | Tender | Jan 1 – Jan 5 | Feb 2 – Feb 9 | Mar 24 – Apr 13 | — |
| Summer squash / zucchini | Tender | — | Feb 2 – Feb 9 | Mar 19 – Apr 3 | — |
| Bush bean | Tender | — | Feb 2 – Feb 9 | Mar 24 – Apr 3 | Oct 17 – Oct 27 |
| Sweet corn | Tender | — | Jan 26 – Feb 9 | Mar 27 – Apr 26 | — |
| Basil | Very tender | Jan 1 | Feb 2 – Feb 9 | Mar 4 – Mar 19 | — |
| Lettuce | Half-hardy | Jan 1 | Jan 1 – Jan 12 | Feb 15 – Mar 2 | Oct 3 – Oct 18 |
| Pea | Hardy | — | Jan 1 | Feb 25 – Mar 12 | Sep 23 – Oct 8 |
| Spinach | Hardy | — | Jan 1 | Feb 10 – Feb 20 | Oct 13 – Oct 23 |
| Carrot | Half-hardy | — | Jan 5 – Jan 12 | Mar 6 – Mar 26 | Sep 13 – Oct 3 |
| Broccoli | Half-hardy | Jan 1 | Jan 1 – Jan 12 | Feb 25 – Mar 17 | Sep 18 – Oct 8 |
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.
Frost & freeze dates
From NOAA's 1991–2020 Climate Normals at station USC00027398. 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 (p10 for spring, p90 for fall) — 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 | Feb 22 | Mar 18 | Dec 2 | Dec 18 | 282 |
| 32°F (freeze) | Jan 26 | Feb 25 | Dec 16 | Jan 17 | 326 |
| 28°F | Jan 7 | Feb 9 | Dec 28 | Feb 3 | 363 |
| 24°F | Jan 6 | Feb 8 | Jan 5 | Feb 8 | 365 |
32°F is the standard "freeze" line that damages tender crops; lighter 36°F frost can nip the most cold-sensitive plants, while hardy crops shrug off light frost down toward 28°F. Use the threshold that matches what you are protecting.
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. Warm-season crops need a long, warm GDD total; a short, cool GDD total favors greens and brassicas.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 7,487 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 10,999 | cool-season crops (brassicas, greens) |
Hardiness zone 9a
Tucson sits in USDA plant hardiness zone 9a on the 2023 map — meaning its average annual extreme minimum winter temperature is about 20 to 25 °F. That number 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.
Explore more places in zone 9a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Tucson?
- Tucson, Arizona is in USDA plant hardiness zone 9a on the 2023 map (average annual extreme minimum temperature 20 to 25 °F) — from the USDA Plant Hardiness Zone Map 2023, matched to this location's ZIP. See the methodology page for sources.
- When is the last frost in Tucson?
- The average (median) last spring frost at 32°F is around January 26, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as February 25, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Tucson?
- The average first fall frost at 32°F is around December 16. That leaves a growing season of about 326 days between the average last spring and first fall frosts.
- When should I start tomatoes in Tucson?
- Start tomato seeds indoors about Jan 1 and transplant them outside about Feb 2 – Feb 9, once the danger of frost has passed. Estimated first harvest is around Apr 3 – Apr 23.
- How long is the growing season in Tucson?
- About 326 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~January 26) and the average first fall frost (~December 16). Cold-hardy crops extend usable time at both ends; frost-tender crops fit inside it.
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020 for station USC00027398 (Saguaro Np, 1.9 km away). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to this 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.