When to Plant Summer Squash and Zucchini in California: Planting Months by Region
UC Master Gardener Program’s own summer squash dates for California, row by row and never averaged, beside NOAA frost dates for Sacramento Executive Airport, Santa Rosa Sonoma County Airport, and Imperial County Airport.
Updated
Figures checked against their sources on ; next check .
Open UC Master Gardener Program’s calendar to the summer squash line under the heading “squash, summer” and you find 4 regions, each with its own planting-month entries. No exact days appear in the first column. It reads North & North Coast (May–July), South Coast (April–June), Interior Valleys (April–July), and Desert Valleys (Feb–Mar; Aug–Sep). The page’s note says planting dates are for seed unless noted otherwise.
The summer squash windows by region
The page files summer squash as a warm-season crop.
| Region | Recommended planting months |
|---|---|
| North & North Coast | May–July |
| South Coast | April–June |
| Interior Valleys | April–July |
| Desert Valleys | Feb–Mar; Aug–Sep |
What to know about this source
The UC Master Gardener Program’s planting table covers four regions: North and North Coast (Monterey County north), South Coast (San Luis Obispo County south), the Interior Valleys and the Desert Valleys (Imperial and Coachella). The page says its dates are based on the average temperatures for each region and may need adjusting if your area varies widely from the average.
Starting summer squash indoors
How early to sow indoors depends on the crop more than the state, and the saved sources agree on the shape if not the numbers; UNH’s figure is 3 to 4 weeks.
Of the saved sources, one gives weeks for summer squash (UNH) and one gives a handling tip (Minnesota).
In the garden itself, UNH sows summer squash once the soil reaches 70 °F, which a soil thermometer answers better than any calendar.
| Source | What it says |
|---|---|
| University of New Hampshire | 3 to 4 weeks from seed to transplant; 2 weeks after the last frost is safe to set out |
| University of Minnesota | Cucumbers and squash transplant poorly, so raise them in fiber or paper pots that break down in the soil |
Where the frost dates fall in California
The 50% date is the even-odds one: in half of the years the last spring 32°F night comes on or after it, and the first fall one on or before it. Each station below links to the frost dates tool.
The last column maps a station to a region only where UC Master Gardener Program or its county list settles it.
| Station | Last spring 32°F | First fall 32°F | Region in California’s calendar |
|---|---|---|---|
| Sacramento Executive Airport, California | February 2 | December 2 | Interior Valleys |
| Santa Rosa Sonoma County Airport, California | March 2 | November 20 | North & North Coast |
| Imperial County Airport, California | January 14 | December 24 | Desert Valleys |
Worked example
Start from Santa Rosa Sonoma County Airport: the station’s median last spring freeze is March 2, and its median first fall freeze is November 20.
The North & North Coast entry runs May to July. Place March 2 on it and the date falls before the window opens.
Treat the result as a way to see how far the printed dates sit from a real frost record. Your yard may run weeks off the station, so repeat the sum with the station closest to you.
Before you rely on these dates
The page suggests contacting experienced gardeners in your community to find more precise dates.
Treat the table as a starting range and look at the ten-day forecast before setting out anything tender.
Sources (4)
- UC Master Gardener Program, University of California Agriculture and Natural Resources, Time of planting (table adapted from the California Master Gardener Handbook, Table 13.2) ucanr.edu
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020, annual and seasonal normals (frost/freeze probabilities by station) ncei.noaa.gov
- University of New Hampshire Cooperative Extension, Growing Vegetables: When to Plant Your Vegetable Garden (fact sheet) extension.unh.edu
- University of Minnesota Extension, Starting seeds indoors (page reviewed 2026) extension.umn.edu