When to plant summer squash / zucchini in Missoula
Summer squash / Zucchini is frost-tender, so every date keys off Missoula's last spring frost of May 15.
Step 1 · Sow
Start seeds indoors
May 12 – Jun 2
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jul 2 – Jul 23
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 16 – Aug 31
Picking runs until conditions turn against the crop.
Window
Days to maturity
45 – 60 d
Missoula's 138-day season leaves this much room.
Summer squash / Zucchini on Missoula'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 15
OCT 4
Common questions
When can I sow summer squash / zucchini outdoors in Missoula?
Direct-sow around early July (Jul 2–Jul 23) in Missoula, based on its local frost dates. Confidence 81%.
When will summer squash / zucchini be ready to harvest in Missoula?
Expect to harvest from around mid August (Aug 16–Aug 31) in Missoula, based on its local frost dates. Confidence 75%.
When should I start summer squash / zucchini seeds indoors in Missoula?
Start seeds indoors around mid May (May 12–Jun 2) in Missoula, based on its local frost dates. Confidence 79%.
When can I transplant summer squash / zucchini outdoors in Missoula?
Transplant outdoors around early July (Jul 2–Jul 23) in Missoula, based on its local frost dates. Confidence 81%.
How long is the growing season in Missoula?
Missoula has roughly 138 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 Missoula's frost dates.
Confidence 83/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.