Michigan · zones 4b–6b
When to plant green beans in Michigan.
Sow between May 5 to Jun 25 in a typical year, keyed to Michigan's median last frost around May 5. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Green Beans dates for a typical Michigan season.
Direct sow
May 5 to Jun 25
Keyed to the ~May 5 last frost. Sow 1" deep, 3" apart.
Harvest
~55 days later
~0.75 lb per plant over ~3 weeks.
Michigan spans more than one climate: Zone 6 is the most common zone, but the state runs 4b to 6b. 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.
Michigan growing notes
Succession sowing fits several rounds of beans into a Michigan season.
Stacking sowings across a 156-day season
With a bean maturing in about 55 days, Michigan's frost-free window, averaging near 156 days on the statewide gauge but running considerably shorter up north and longer along the southwest lakeshore, still leaves room for several full rounds of bush beans rather than one big planting, and succession is the single biggest lever a home grower has here. Sow a new short row every 2 to 3 weeks instead of one large block, and the harvest spreads into a steady trickle of pickable beans rather than one overwhelming week followed by nothing at all.
The cutoff that matters more than any calendar page is counting backward from the season's end: a round needs its full 55 days plus about a week of slack for cool weather slowing things down late in the year, so stop starting new rows once that math runs out. A soil temperature test decides the early end too; beans rot in cold wet ground instead of sprouting, so wait until a handful of soil held in your palm feels warm all the way through, not just on the surface.
Mexican bean beetle looks like a good bug until it isn't
Mexican bean beetle is the pest that fools new Michigan gardeners because the adult looks almost exactly like a large, coppery ladybug, and gardeners leave it alone assuming it eats aphids. It does not; both the adult and its fuzzy yellow larvae skeletonize bean leaves from the underside, leaving a lacy net of veins where solid green used to be. Flip a few leaves weekly starting as soon as plants have their first true leaves, since the yellow egg clusters and larvae are both easy to crush by hand before numbers build up.
Beans planted early in the season generally dodge the worst of it, since beetle populations build through summer and peak in the later rounds; that is one more reason to lean on succession planting rather than one big early sowing that peaks right when beetle pressure does. Row cover over young plants works too, but has to come off once flowers open, since beans need pollinator access to set pods properly.
Rust and mildew ride in on wet leaves
Late-summer rounds are the ones that run into rust and powdery mildew, both of which need one thing in common: leaves that stay wet or humid for hours at a stretch. Rust shows as small rust-orange freckles on the leaf underside; powdery mildew shows as a white dusty coating on top. Both spread fastest through a dense planting where air cannot move, so a 3-inch in-row spacing is close to the minimum a home planting should use, not a target to crowd tighter than.
Water at the base of the plant in the morning rather than overhead in the evening, since wet foliage overnight is exactly the window both diseases need to establish. If rust or mildew shows up on an early round anyway, pull the worst-hit plants rather than trying to treat them, and give the next succession sowing a few extra inches of spacing; thinning airflow does more against this particular pair of diseases than any spray a home garden typically keeps on hand.
In Michigan: watch for
The pests that find green beans here.
A middle-length season, about 156 frost-free days, means bush bean overlaps mexican bean beetle for a stretch each summer. Check plants every week or two and treat early.
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: Michigan gives green beans about 156 frost-free days, and it needs roughly 55 days to a first harvest. That fits about 11 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting green beans in Michigan: questions
When should I plant green beans in Michigan?+
In a typical Michigan year, sow green beans between May 5 to Jun 25, keyed to the state's median last frost around May 5. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Michigan?+
Michigan spans zones 4b–6b, 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.