Gardening in Tucson, AZ
This metro spans USDA zones 8b to 9b, so there is no single zone for Tucson, AZ and anyone who gives you one is rounding. 48% of its ZIP codes are zone 9b; the rest are not.
Which zone you are in depends where you are
Tucson, AZ covers 3 hardiness zones. A guide that gives the metro one zone has picked whichever is largest and rounded everyone else into it — which is fine for the 48% in zone 9b and wrong for the other 52%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 9b | 24 | 48% | |
| 9a | 21 | 42% | |
| 8b | 5 | 10% |
Zones are published per ZIP code, so yours is exact even though the metro's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Those are the earliest and latest medians among the 18 stations serving this metro — not an average, and not one station standing in for the rest. Half of years freeze later than a station's own median.
The spread is the point. Even in a metro that is one hardiness zone throughout, its stations disagree about the last spring freeze. Hardiness zone and frost date measure different things — a zone is the average annual coldest night, a freeze date is when the season turns — and a place can be uniform in one and varied in the other. Use the tools below with your own ZIP rather than the ends of this range.
Your growing season
NOAA publishes a growing-season length for each station, and across the 18 stations serving Tucson, AZ it runs 195–347 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 80–103 °F , at or above the 90 °F point where cool-season crops bolt and tomato and pepper pollen fails — so midsummer sowings of lettuce and its relatives are worth holding here.
When to start seeds in Tucson, AZ
Every spring job for 63 crop dates, counted from this metro's own last spring freeze. Each is a range across all 18 stations — the earliest and latest that job falls anywhere in the metro — because no one station speaks for the whole area.
| Crop | Job | When | Offset |
|---|---|---|---|
| Bok Choy | Start indoors | January 1 – December 31 | 5 weeks before |
| Green Onions | Start indoors | January 1 – December 31 | 8 weeks before |
| Kohlrabi | Start indoors | January 1 – December 31 | 5 weeks before |
| Peppers | Start indoors | January 1 – December 31 | 8 weeks before |
| Swiss Chard | Start indoors | January 1 – December 31 | 5 weeks before |
| Dill | Direct sow | January 3 – April 19 | 1 week before |
| Cabbage | Set out | January 5 – December 30 | 3 weeks before |
| Carrots | Direct sow | January 5 – December 30 | 3 weeks before |
| Collards | Direct sow | January 5 – December 30 | 3 weeks before |
| Collards | Set out | January 5 – December 30 | 3 weeks before |
| Cucumbers | Start indoors | January 5 – December 30 | 3 weeks before |
| Green Onions | Set out | January 5 – December 30 | 3 weeks before |
| Kale | Direct sow | January 5 – December 30 | 3 weeks before |
| Kale | Set out | January 5 – December 30 | 3 weeks before |
| Kohlrabi | Direct sow | January 5 – December 30 | 3 weeks before |
| Kohlrabi | Set out | January 5 – December 30 | 3 weeks before |
| Leaf Lettuce | Direct sow | January 5 – December 30 | 3 weeks before |
| Pumpkins | Start indoors | January 5 – December 30 | 3 weeks before |
| Summer Squash | Start indoors | January 5 – December 30 | 3 weeks before |
| Winter Squash | Start indoors | January 5 – December 30 | 3 weeks before |
| Zucchini | Start indoors | January 5 – December 30 | 3 weeks before |
| Bok Choy | Direct sow | January 6 – December 27 | 2 weeks before |
| Bok Choy | Set out | January 6 – December 27 | 2 weeks before |
| Broccoli | Set out | January 6 – December 27 | 2 weeks before |
| Cilantro | Direct sow | January 6 – December 27 | 2 weeks before |
| Leaf Lettuce | Set out | January 6 – December 27 | 2 weeks before |
| Swiss Chard | Direct sow | January 6 – December 27 | 2 weeks before |
| Swiss Chard | Set out | January 6 – December 27 | 2 weeks before |
| Arugula | Direct sow | January 7 – December 29 | 4 weeks before |
| Baby Salad Greens | Direct sow | January 7 – December 29 | 4 weeks before |
| Beets | Direct sow | January 7 – December 29 | 4 weeks before |
| Green Onions | Direct sow | January 7 – December 29 | 4 weeks before |
| Mustard Greens | Direct sow | January 7 – December 29 | 4 weeks before |
| Okra | Start indoors | January 7 – December 29 | 4 weeks before |
| Radishes | Direct sow | January 7 – December 29 | 4 weeks before |
| Turnips | Direct sow | January 7 – December 29 | 4 weeks before |
| Broccoli | Start indoors | January 9 – December 31 | 6 weeks before |
| Cabbage | Start indoors | January 9 – December 31 | 6 weeks before |
| Collards | Start indoors | January 9 – December 31 | 6 weeks before |
| Kale | Start indoors | January 9 – December 31 | 6 weeks before |
| Leaf Lettuce | Start indoors | January 9 – December 31 | 6 weeks before |
| Peas | Direct sow | January 9 – December 31 | 6 weeks before |
| Spinach | Direct sow | January 9 – December 31 | 6 weeks before |
| Sweet Potato | Start indoors | January 9 – December 31 | 6 weeks before |
| Tomatoes | Start indoors | January 9 – December 31 | 6 weeks before |
| Bush Beans | Direct sow | January 17 – May 3 | 1 week after |
| Cucumbers | Set out | January 17 – May 3 | 1 week after |
| Pumpkins | Direct sow | January 17 – May 3 | 1 week after |
| Pumpkins | Set out | January 17 – May 3 | 1 week after |
| Summer Squash | Direct sow | January 17 – May 3 | 1 week after |
| Summer Squash | Set out | January 17 – May 3 | 1 week after |
| Sweet Corn | Direct sow | January 17 – May 3 | 1 week after |
| Tomatoes | Set out | January 17 – May 3 | 1 week after |
| Winter Squash | Direct sow | January 17 – May 3 | 1 week after |
| Winter Squash | Set out | January 17 – May 3 | 1 week after |
| Zucchini | Direct sow | January 17 – May 3 | 1 week after |
| Zucchini | Set out | January 17 – May 3 | 1 week after |
| Cucumbers | Direct sow | January 24 – May 10 | 2 weeks after |
| Okra | Direct sow | January 24 – May 10 | 2 weeks after |
| Okra | Set out | January 24 – May 10 | 2 weeks after |
| Peppers | Set out | January 24 – May 10 | 2 weeks after |
| Southern Peas | Direct sow | January 24 – May 10 | 2 weeks after |
| Sweet Potato | Set out | January 24 – May 10 | 2 weeks after |
The week offsets are conventional extension guidance and vary by variety; the freeze dates they are counted from are measured. For a single date rather than a range, run when do I start my seeds? with your own ZIP code.
What survives the winter changes across Tucson, AZ
Of 74 perennial fruits, nuts, berries, vegetables and herbs, 54 come through the winter in zone 8b and only 40 in zone 9b. That is a different garden at each end of the same metro.
| Zone | ZIPs | Survive | Fail for being too warm |
|---|---|---|---|
| 8b | 5 | 54 of 74 | 11 |
| 9a | 21 | 46 of 74 | 25 |
| 9b | 24 | 40 of 74 | 32 |
The last column is the counterintuitive one, and it is why the totals do not simply rise as the winters get milder. Most temperate fruit needs a documented number of hours below about 45 °F to break dormancy and set a crop, so an apple fails in a winter that is too warm; currants and rhubarb cook in the summer heat that comes with it. See the full list with reasons.
The 18 stations behind these numbers
Every figure above comes from these, and each is named so you can check it. Distances vary by ZIP code, so the tools report yours rather than this page guessing.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Ajo, AZ | USC00020080 | January 10 | December 21 | 347 days |
| Anvil Rch, AZ | USC00020287 | March 27 | November 9 | 226 days |
| Catalina SP, AZ | USC00021357 | April 2 | November 11 | 222 days |
| Green Valley, AZ | USC00023668 | February 25 | November 27 | 276 days |
| Kitt Peak, AZ | USC00024675 | April 26 | November 4 | 195 days |
| Mt Lemmon Willow Canyon, AZ | USC00025737 | April 1 | November 19 | 229 days |
| Organ Pipe Cactus Nm, AZ | USC00026132 | February 4 | December 15 | 314 days |
| Saguaro Np, AZ | USC00027398 | January 26 | December 16 | 326 days |
| Santa Rita Exp Range, AZ | USC00027593 | February 25 | December 5 | 282 days |
| Sasabe, AZ | USC00027619 | March 21 | November 20 | 246 days |
| Tohono Chul, AZ | USC00028590 | February 26 | December 4 | 279 days |
| Tucson 11 W, AZ | USW00053131 | February 8 | December 10 | 303 days |
| Tucson 17 NW, AZ | USC00028795 | February 23 | December 6 | 287 days |
| Tucson Camp Ave Exp, AZ | USC00028796 | February 20 | November 27 | 280 days |
| Tucson INTL AP, AZ | USW00023160 | February 5 | December 9 | 307 days |
| Tucson U Of A #1, AZ | USC00028817 | February 11 | December 2 | 293 days |
| Tucson Wfo, AZ | USC00028815 | January 20 | December 17 | 332 days |
| Tumacacori Nm, AZ | USC00028865 | April 5 | November 10 | 217 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Work out your own dates
Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.
- What survives my winter?
Runs on the hardiness zone, so it answers for all of Tucson, AZ at once — zone across 74 perennial fruits, berries, vegetables and herbs.
- When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
- When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
- What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.
Where these numbers come from
The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates are NOAA's 1991–2020 Climate Normals, read from every station whose normals cover a ZIP code in this metro. Nothing here is estimated, and no station stands in for another.
This page names no single station on purpose. Picking one to represent a metro sounds reasonable and is not: the station serving the most ZIP codes is an artifact of where ZIP centroids happen to fall, and it selects a lock on the Monongahela for Pittsburgh and a far southern suburb for Chicago. A range across every station is true; a single cited date for a whole metro is not.