Idaho · zones 5b–7b
When to plant green beans in Idaho.
Sow between May 11 to Jul 1 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
Green Beans dates for a typical Idaho season.
Direct sow
May 11 to Jul 1
Keyed to the ~May 11 last frost. Sow 1" deep, 3" apart.
Harvest
~55 days later
~0.75 lb per plant over ~3 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
Bush beans reward the Treasure Valley's long warm stretch about as well as anything grown here, because each sowing blooms hard, fills its pods, and finishes within weeks rather than months.
Why this crop gets sown nine times instead of once
A bush bean plant is not built for a long trickle of production the way a climbing pole variety is. It puts on growth, blooms hard all at once, fills its pods over a short stretch, and then winds down for good, which is exactly why one planting was never going to carry a whole Idaho season by itself. Sown about three inches apart down the row and ready in roughly 55 days, this crop is quick enough that something like nine separate sowings fit across the growing season, each one timed a couple of weeks behind the last, so a new planting is just coming into full production as an older one fades.
Beans have no tolerance for cold at all, which is why there is no separate fall planting window here. A planting timed to mature after the season's first frost never gets the chance to. All nine rounds have to land inside the same frost-to-frost stretch instead, and that stretch runs longest in the Treasure Valley, where the warm season starts earlier and holds later, letting a grower there cycle through most or all of those sowings. Gardeners working colder ground, whether that is higher elevation or a cooler yard farther north, still grow this crop well; they simply fit fewer rounds into the same calendar and get the most out of it by prioritizing the earliest and latest sowings rather than trying to squeeze in all nine.
The beetle that looks like help
Mexican bean beetle is the pest most likely to go unnoticed on this crop, because the adult is coppery orange with black spots and gets mistaken for a ladybug, its genuinely beneficial look-alike, often until real damage is already done. The giveaway is underneath the leaf: clusters of yellow-orange eggs standing on end, and later, spiny yellow larvae that look nothing like a ladybug at any stage, both feeding on leaf tissue from below and leaving a lacy, skeletonized leaf behind.
Checking the underside of leaves through the row, rather than glancing at the tops of the plants, is what actually catches this pest before it has built up a second generation. It is worth a closer look than most gardeners give it precisely because the adult reads as beneficial at a glance; a beetle that gets a pass because it looks helpful is the one doing the most damage by the time anyone notices the lace pattern in the leaves.
Three diseases with one shared habit behind them
Rust and powdery mildew both show up on the leaves later in the season, rust as small rust-colored pustules on the underside, powdery mildew as the more familiar gray-white dusting on top, and both spread faster through a planting that stays wet into the evening than one watered at the soil line in the morning. Anthracnose is the one worth changing behavior for: it spreads on contact with wet foliage, including from a gardener's own hands or clothing brushing damp leaves while picking, so simply staying out of the rows until the dew has burned off does more against this disease than anything sprayed on after it shows up.
Aphids turn up on new growth and pods too, at numbers small enough on this crop that the ants sometimes found tending them for honeydew are more noticeable than the aphids themselves. None of the four is usually the reason a planting fails outright here; at something like three-quarters of a pound of pods per plant, a single sowing lost to one of them is a gap in the picking basket for a couple of weeks, not the loss of the season, since another sowing a couple of weeks behind it is already coming on.
In Idaho: watch for
The pests that find green beans here.
The short season here, about 140 frost-free days, keeps bush bean in front of mexican bean beetle only briefly. One early row cover usually carries a planting through the worst of it.
Coppery ladybug-like beetles; leaves skeletonized to lace.
Organic fix: Handpick adults and yellow egg clusters; neem.
Orange or white spots on leaves late in the season.
Organic fix: Water at the base, space plants, spray neem.
Anthracnose
Sunken dark-red cankers on the pods, and leaf veins turning brick-red to black underneath.
Organic fix: Start with certified seed, water at the base, and stay out of the patch while the leaves are wet.
Your season math: Idaho gives green beans about 140 frost-free days, and it needs roughly 55 days to a first harvest. That fits about 9 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting green beans in Idaho: questions
When should I plant green beans in Idaho?+
In a typical Idaho year, sow green beans between May 11 to Jul 1, 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 green beans 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.