Casas Adobes, AZ planting zone & frost dates
Casas Adobes is in USDA hardiness zone 9a. The last spring frost usually comes around February 26 and the first fall frost around December 4, for a growing season of about 279 days.
Planting calendar for Casas Adobes
Dates are counted from the average last spring frost (February 26) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Jan 1 – Jan 15 Transplant outdoors: Mar 5 – Mar 12 |
| Peppers | Start seeds indoors: Dec 18 – Jan 1 Transplant outdoors: Mar 12 – Mar 19 |
| Eggplant | Start seeds indoors: Dec 18 – Jan 1 Transplant outdoors: Mar 12 – Mar 19 |
| Broccoli | Start seeds indoors: Dec 18 – Jan 1 Transplant outdoors: Jan 29 – Feb 12 |
| Cabbage | Start seeds indoors: Dec 18 – Jan 1 Transplant outdoors: Jan 29 – Feb 12 |
| Onions (sets) | Plant outdoors: Jan 29 – Feb 12 |
| Peas | Sow outdoors: Jan 15 – Jan 29 |
| Spinach | Sow outdoors: Jan 15 – Jan 29 |
| Lettuce | Sow outdoors: Jan 29 – Feb 12 |
| Carrots | Sow outdoors: Jan 29 – Feb 12 |
| Potatoes | Plant outdoors: Jan 29 – Feb 12 |
| Beans | Sow outdoors: Mar 5 – Mar 12 |
| Sweet corn | Sow outdoors: Mar 5 – Mar 12 |
| Cucumbers | Sow outdoors: Mar 5 – Mar 12 |
| Squash & zucchini | Sow outdoors: Mar 5 – Mar 12 |
| Basil | Start seeds indoors: Jan 15 – Jan 29 Transplant outdoors: Mar 5 – Mar 12 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 9 (8 weeks before the average first fall frost on Dec 4).
Useful for zone 9a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Shade cloth — for hot summers
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Jan 29 | Feb 26 | Mar 18 |
| First 32°F frost in fall is before | Dec 19 | Dec 4 | Nov 17 |
How to read it: in spring there is a 10% chance of a frost after March 18, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 17. A hard freeze (28°F) usually ends around February 1.
Nearby cities
- Flowing Wells zone 9b, last frost Feb 11
- Oro Valley zone 9a, last frost Apr 2
- Catalina Foothills zone 9a, last frost Feb 20
- Tucson zone 9b, last frost Jan 20
- Tucson Estates zone 9b, last frost Feb 8
- Drexel Heights zone 9b, last frost Feb 5
- Saddlebrooke zone 9a, last frost Apr 2
- Marana zone 9b, last frost Feb 23
Questions
What growing zone is Casas Adobes, AZ?
Casas Adobes is in USDA Plant Hardiness Zone 9a (average extreme winter low 20°F to 25°F), according to the USDA 2023 map.
When is the last frost in Casas Adobes?
The average last spring frost (32°F) in Casas Adobes is February 26. There is still a 10% chance of frost until March 18.
When can I plant tomatoes in Casas Adobes?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 5 – Mar 12. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Tohono Chul, AZ (USC00028590), 2.2 km (1.4 mi) from the city center, elevation 770 m, based on 5 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.