When to plant summer squash / zucchini in Duluth
Summer squash / Zucchini is frost-tender, so every date keys off Duluth's last spring frost of May 10.
Step 1 · Sow
Start seeds indoors
May 8 – May 29
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jul 3 – Jul 24
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 17 – Sep 1
Picking runs until conditions turn against the crop.
Window
Days to maturity
45 – 60 d
Duluth's 150-day season leaves this much room.
Summer squash / Zucchini on Duluth'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
MAY 10
OCT 7
Common questions
When can I sow summer squash / zucchini outdoors in Duluth?
Direct-sow around early July (Jul 3–Jul 24) in Duluth, based on its local frost dates. Confidence 84%.
When will summer squash / zucchini be ready to harvest in Duluth?
Expect to harvest from around mid August (Aug 17–Sep 1) in Duluth, based on its local frost dates. Confidence 78%.
When should I start summer squash / zucchini seeds indoors in Duluth?
Start seeds indoors around early May (May 8–May 29) in Duluth, based on its local frost dates. Confidence 83%.
When can I transplant summer squash / zucchini outdoors in Duluth?
Transplant outdoors around early July (Jul 3–Jul 24) in Duluth, based on its local frost dates. Confidence 84%.
How long is the growing season in Duluth?
Duluth has roughly 150 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 Duluth's frost dates.
Confidence 87/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.