When to plant summer squash / zucchini in San Bernardino

Summer squash / Zucchini is frost-tender, so every date keys off San Bernardino's last spring frost of Feb 23.
Step 1 · Sow
Start seeds indoors
Mar 8 – Mar 29
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 10 – May 1
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 25 – Jun 9
Picking runs until conditions turn against the crop.
Window
Days to maturity
45 – 60 d
San Bernardino's 284-day season leaves this much room.
Summer squash / Zucchini on San Bernardino's growing year
Frost-bounded season with crops mapped onto the 12-month axis.
Frost risk Growing Harvest
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
FEB 23
DEC 9

Common questions

When can I sow summer squash / zucchini outdoors in San Bernardino?

Direct-sow around early April (Apr 10–May 1) in San Bernardino, based on its local frost dates. Confidence 76%.

When will summer squash / zucchini be ready to harvest in San Bernardino?

Expect to harvest from around late May (May 25–Jun 9) in San Bernardino, based on its local frost dates. Confidence 70%.

When should I start summer squash / zucchini seeds indoors in San Bernardino?

Start seeds indoors around early March (Mar 8–Mar 29) in San Bernardino, based on its local frost dates. Confidence 74%.

When can I transplant summer squash / zucchini outdoors in San Bernardino?

Transplant outdoors around early April (Apr 10–May 1) in San Bernardino, based on its local frost dates. Confidence 76%.

How long is the growing season in San Bernardino?

San Bernardino has roughly 284 frost-free days, which is enough time to grow summer squash / zucchini to maturity outdoors.

The rule of thumb

Sow summer squash / zucchini 6–8 weeks before your last spring frost; plant out 2–3 weeks after it. Every date on this page is derived from that rule and San Bernardino's frost dates.

Confidence 78/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.