San Luis Obispo, CA planting zone & frost dates
San Luis Obispo is in USDA hardiness zone 10a. The last spring frost usually comes around January 16 and the first fall frost around December 25, for a growing season of about 349 days.
Planting calendar for San Luis Obispo
Dates are counted from the average last spring frost (January 16) 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: Nov 21 – Dec 5 Transplant outdoors: Jan 23 – Jan 30 |
| Peppers | Start seeds indoors: Nov 7 – Nov 21 Transplant outdoors: Jan 30 – Feb 6 |
| Eggplant | Start seeds indoors: Nov 7 – Nov 21 Transplant outdoors: Jan 30 – Feb 6 |
| Broccoli | Start seeds indoors: Nov 7 – Nov 21 Transplant outdoors: Dec 19 – Jan 2 |
| Cabbage | Start seeds indoors: Nov 7 – Nov 21 Transplant outdoors: Dec 19 – Jan 2 |
| Onions (sets) | Plant outdoors: Dec 19 – Jan 2 |
| Peas | Sow outdoors: Dec 5 – Dec 19 |
| Spinach | Sow outdoors: Dec 5 – Dec 19 |
| Lettuce | Sow outdoors: Dec 19 – Jan 2 |
| Carrots | Sow outdoors: Dec 19 – Jan 2 |
| Potatoes | Plant outdoors: Dec 19 – Jan 2 |
| Beans | Sow outdoors: Jan 23 – Jan 30 |
| Sweet corn | Sow outdoors: Jan 23 – Jan 30 |
| Cucumbers | Sow outdoors: Jan 23 – Jan 30 |
| Squash & zucchini | Sow outdoors: Jan 23 – Jan 30 |
| Basil | Start seeds indoors: Dec 5 – Dec 19 Transplant outdoors: Jan 23 – Jan 30 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 30 (8 weeks before the average first fall frost on Dec 25).
Useful for zone 10a 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
As an Amazon Associate, FrostZoneMap earns from qualifying purchases, at no extra cost to you.
Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Dec 11 | Jan 16 | Feb 26 |
| First 32°F frost in fall is before | Feb 12 | Dec 25 | Nov 25 |
How to read it: in spring there is a 10% chance of a frost after February 26, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 25. A hard freeze (28°F) usually ends around January 9.
Hardiness zone by ZIP code in San Luis Obispo
- 93401 zone 9b
- 93403 zone 10a
- 93405 zone 9b
- 93406 zone 10a
- 93407 zone 9b
- 93408 zone 10a
- 93409 zone 9b
- 93410 zone 9b
Nearby cities
- Grover Beach zone 10a
- Los Osos zone 10a
- Arroyo Grande zone 10a
- Atascadero zone 9a, last frost Mar 15
- Morro Bay zone 10a
- Nipomo zone 9b, last frost Feb 4
- Paso Robles zone 9a, last frost Mar 15
- Santa Maria zone 9b, last frost Feb 4
Questions
What growing zone is San Luis Obispo, CA?
San Luis Obispo is in USDA Plant Hardiness Zone 10a (average extreme winter low 30°F to 35°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 9b.
When is the last frost in San Luis Obispo?
The average last spring frost (32°F) in San Luis Obispo is January 16. There is still a 10% chance of frost until February 26.
When can I plant tomatoes in San Luis Obispo?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jan 23 – Jan 30. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station San Luis Obispo Poly, CA (USC00047851), 2.5 km (1.6 mi) from the city center, elevation 94 m, based on 28 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.