Gardening in Vallejo, CA
Every ZIP code in this metro is USDA zone 9b. That is unusual — most metros span several zones — and it means the one number people usually look up is the same wherever you are here.
Your freeze dates
Those are the earliest and latest medians among the 6 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 6 stations serving Vallejo, CA it runs 283–346 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 85–95 °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 Vallejo, CA
Every spring job for 63 crop dates, counted from this metro's own last spring freeze. Each is a range across all 6 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 | Direct sow | January 1 – December 29 | 2 weeks before |
| Bok Choy | Set out | January 1 – December 29 | 2 weeks before |
| Broccoli | Set out | January 1 – December 29 | 2 weeks before |
| Cilantro | Direct sow | January 1 – December 29 | 2 weeks before |
| Leaf Lettuce | Set out | January 1 – December 29 | 2 weeks before |
| Swiss Chard | Direct sow | January 1 – December 29 | 2 weeks before |
| Swiss Chard | Set out | January 1 – December 29 | 2 weeks before |
| Arugula | Direct sow | January 3 – December 20 | 4 weeks before |
| Baby Salad Greens | Direct sow | January 3 – December 20 | 4 weeks before |
| Beets | Direct sow | January 3 – December 20 | 4 weeks before |
| Green Onions | Direct sow | January 3 – December 20 | 4 weeks before |
| Mustard Greens | Direct sow | January 3 – December 20 | 4 weeks before |
| Okra | Start indoors | January 3 – December 20 | 4 weeks before |
| Radishes | Direct sow | January 3 – December 20 | 4 weeks before |
| Turnips | Direct sow | January 3 – December 20 | 4 weeks before |
| Dill | Direct sow | January 5 – February 11 | 1 week before |
| Bok Choy | Start indoors | January 6 – December 27 | 5 weeks before |
| Kohlrabi | Start indoors | January 6 – December 27 | 5 weeks before |
| Swiss Chard | Start indoors | January 6 – December 27 | 5 weeks before |
| Broccoli | Start indoors | January 7 – December 30 | 6 weeks before |
| Cabbage | Start indoors | January 7 – December 30 | 6 weeks before |
| Collards | Start indoors | January 7 – December 30 | 6 weeks before |
| Kale | Start indoors | January 7 – December 30 | 6 weeks before |
| Leaf Lettuce | Start indoors | January 7 – December 30 | 6 weeks before |
| Peas | Direct sow | January 7 – December 30 | 6 weeks before |
| Spinach | Direct sow | January 7 – December 30 | 6 weeks before |
| Sweet Potato | Start indoors | January 7 – December 30 | 6 weeks before |
| Tomatoes | Start indoors | January 7 – December 30 | 6 weeks before |
| Cabbage | Set out | January 10 – December 27 | 3 weeks before |
| Carrots | Direct sow | January 10 – December 27 | 3 weeks before |
| Collards | Direct sow | January 10 – December 27 | 3 weeks before |
| Collards | Set out | January 10 – December 27 | 3 weeks before |
| Cucumbers | Start indoors | January 10 – December 27 | 3 weeks before |
| Green Onions | Set out | January 10 – December 27 | 3 weeks before |
| Kale | Direct sow | January 10 – December 27 | 3 weeks before |
| Kale | Set out | January 10 – December 27 | 3 weeks before |
| Kohlrabi | Direct sow | January 10 – December 27 | 3 weeks before |
| Kohlrabi | Set out | January 10 – December 27 | 3 weeks before |
| Leaf Lettuce | Direct sow | January 10 – December 27 | 3 weeks before |
| Pumpkins | Start indoors | January 10 – December 27 | 3 weeks before |
| Summer Squash | Start indoors | January 10 – December 27 | 3 weeks before |
| Winter Squash | Start indoors | January 10 – December 27 | 3 weeks before |
| Zucchini | Start indoors | January 10 – December 27 | 3 weeks before |
| Bush Beans | Direct sow | January 19 – February 25 | 1 week after |
| Cucumbers | Set out | January 19 – February 25 | 1 week after |
| Pumpkins | Direct sow | January 19 – February 25 | 1 week after |
| Pumpkins | Set out | January 19 – February 25 | 1 week after |
| Summer Squash | Direct sow | January 19 – February 25 | 1 week after |
| Summer Squash | Set out | January 19 – February 25 | 1 week after |
| Sweet Corn | Direct sow | January 19 – February 25 | 1 week after |
| Tomatoes | Set out | January 19 – February 25 | 1 week after |
| Winter Squash | Direct sow | January 19 – February 25 | 1 week after |
| Winter Squash | Set out | January 19 – February 25 | 1 week after |
| Zucchini | Direct sow | January 19 – February 25 | 1 week after |
| Zucchini | Set out | January 19 – February 25 | 1 week after |
| Cucumbers | Direct sow | January 26 – March 4 | 2 weeks after |
| Okra | Direct sow | January 26 – March 4 | 2 weeks after |
| Okra | Set out | January 26 – March 4 | 2 weeks after |
| Peppers | Set out | January 26 – March 4 | 2 weeks after |
| Southern Peas | Direct sow | January 26 – March 4 | 2 weeks after |
| Sweet Potato | Set out | January 26 – March 4 | 2 weeks after |
| Green Onions | Start indoors | November 17 – December 24 | 8 weeks before |
| Peppers | Start indoors | November 17 – December 24 | 8 weeks before |
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 lives through a zone 9b winter
Winter hardiness runs on the zone alone, so this one is exact for the whole of Vallejo, CA rather than a range. Of 74 perennial fruits, nuts, berries, vegetables and herbs, 40 come through a zone 9b winter — the other 34 fail, and not all of them for cold.
Among them: Elderberry, Horseradish, Sunchoke, Walking Onion, Chives, Mint, American Persimmon, French Sorrel. See the full list with reasons.
The 6 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 |
|---|---|---|---|---|
| Antioch Pumping Plt #3, CA | USC00040232 | January 12 | December 19 | 343 days |
| Davis 2 Wsw Exp Farm, CA | USC00042294 | February 10 | December 1 | 295 days |
| Fairfield, CA | USC00042934 | January 15 | December 14 | 336 days |
| Vacaville Nut Tree AP, CA | USW00093241 | February 18 | November 28 | 283 days |
| Vacaville, CA | USC00049200 | January 31 | December 11 | 318 days |
| Vallejo, CA | USC00049219 | January 17 | December 27 | 346 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 Vallejo, CA at once — zone 9b 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.