When to plant summer squash / zucchini in Chicago
Summer squash / Zucchini is frost-tender, so every date keys off Chicago's last spring frost of Apr 10.
Step 1 · Sow
Start seeds indoors
Apr 4 – Apr 25
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
May 18 – Jun 8
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 2 – Jul 17
Picking runs until conditions turn against the crop.
Window
Days to maturity
45 – 60 d
Chicago's 206-day season leaves this much room.
Summer squash / Zucchini on Chicago'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
FROST
FROST
APR 10
OCT 31
Common questions
When can I sow summer squash / zucchini outdoors in Chicago?
Direct-sow around mid May (May 18–Jun 8) in Chicago, based on its local frost dates. Confidence 81%.
When will summer squash / zucchini be ready to harvest in Chicago?
Expect to harvest from around early July (Jul 2–Jul 17) in Chicago, based on its local frost dates. Confidence 76%.
When should I start summer squash / zucchini seeds indoors in Chicago?
Start seeds indoors around early April (Apr 4–Apr 25) in Chicago, based on its local frost dates. Confidence 80%.
When can I transplant summer squash / zucchini outdoors in Chicago?
Transplant outdoors around mid May (May 18–Jun 8) in Chicago, based on its local frost dates. Confidence 81%.
How long is the growing season in Chicago?
Chicago has roughly 206 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 Chicago's frost dates.
Confidence 84/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.