Idaho · zones 5b–7b
When to plant zucchini in Idaho.
Sow between May 18 to Jul 26 in a typical year, keyed to Idaho's median last frost around May 11. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Zucchini dates for a typical Idaho season.
Direct sow
May 18 to Jul 26
Keyed to the ~May 11 last frost. Sow 1" deep, 24" apart.
Harvest
~50 days later
~8 lb per plant over ~5 weeks.
Idaho spans more than one climate: Zone 6 is the most common zone, but the state runs 5b to 7b. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
Idaho growing notes
At 140 days, Idaho's growing season is short enough that a zucchini planting here needs checking every few days, not every few weeks, to keep mildew and two steady pests from getting ahead of it.
A short season still leaves room for four rounds
Speed is what makes this crop work in a season that runs close to 140 days end to end: at about 50 days from seed to first squash, there is still enough room to fit around four sowings staggered a few weeks apart instead of nursing one planting the whole way through, though every round has to land inside that single stretch since there is no separate window waiting later in the fall. Space seedlings a full 24 inches apart in the row and set seed about an inch deep; the wide leaves this crop throws will fill that gap by midsummer.
Fruit size adds up fast once a plant gets going, something like 8 pounds off a single well-sited plant before frost shuts the season down, so the point of four rounds here isn't stretching supply, it's stretching the odds. A setback on the first round, whether from mildew, a bug buildup, or a rough patch of weather, does not cost the whole harvest when a second round is already coming along behind it, and that margin matters more in a state with this little season to spare.
Dry days, cool nights, and a disease that does not need rain to spread
Powdery mildew is the disease that matters most on this crop here, and unlike a lot of garden fungal problems, it does not need rain or standing water on the leaf to get started. It spreads just fine in dry air as long as nights are cool enough for dew to settle on the leaves by morning, a combination that describes a lot of Idaho summers regardless of whether the garden sits on the warmer valley floor or up in higher, cooler ground.
The wide spacing this crop needs helps more than most gardeners expect: at 24 inches between plants, a zucchini's own broad leaves have room to dry out fully once the sun is up, which slows the disease even though it will not stop it outright once the nights turn consistently cool and damp. Once a pale dusting shows up on the oldest leaves, cutting those specific leaves off, not the whole plant, usually keeps the rest producing for weeks longer than leaving infected leaves in place to spread spores onto whatever they touch next.
Squash bugs at the crown, cucumber beetles on the seedlings
Squash bugs on this crop tend to gather where several stems and leaf stalks meet at the crown of the plant, rather than spreading evenly across the canopy the way they might on a more open-growing vine. That makes the crown, not the leaf tips, the first place worth checking, parting the leaves at the base and looking for the grayish, shield-shaped adults or clusters of nymphs before assuming a plant is clean.
Cucumber beetles round out the pests worth watching here, chewing small ragged holes in leaves and occasionally marking young fruit, and they generally do the least damage of the two as long as a planting gets past its first couple of weeks without losing too much leaf area to them. A seedling that keeps most of its first true leaves intact usually outgrows the beetles on its own once the canopy starts filling in and the plant has leaf area to spare.
In Idaho: watch for
The pests that find zucchini here.
The short season here, about 140 frost-free days, keeps squash, summer in front of squash bugs only briefly. One early row cover usually carries a planting through the worst of it.
Gray shield bugs; leaves wilt and get crispy patches.
Organic fix: Lay a board out overnight and collect them at dawn; scrape bronze egg clusters off leaf undersides.
Yellow striped or spotted beetles chewing leaves and blossoms.
Organic fix: Row cover until the first female flowers open, then hand-pick.
White powder coating the leaves late in the season.
Organic fix: Space for airflow, water the soil rather than the leaves, use resistant varieties.
Your season math: Idaho gives zucchini about 140 frost-free days, and it needs roughly 50 days to a first harvest. That fits about 4 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting zucchini in Idaho: questions
When should I plant zucchini in Idaho?+
In a typical Idaho year, sow zucchini between May 18 to Jul 26, keyed to the state's median last frost around May 11. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Idaho?+
Idaho spans zones 5b–7b, mostly zone 6. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many zucchini plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.