Michigan · zones 4b–6b
When to plant tomatoes in Michigan.
Sow or transplant between May 12 to Jul 12 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
Tomatoes dates for a typical Michigan season.
1 · Start indoors
Mar 31 to May 31
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
May 12 to Jul 12
Keyed to the ~May 5 last frost. Sow 0.25" deep, 24" apart.
Harvest
~73 days later
~12 lb per plant over ~8 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
Two zones apart, the Upper Peninsula and Detroit grow different tomatoes.
A garden 300 miles north is nearly two zones colder
Michigan's hardiness zones run from about 4b in the Upper Peninsula up to 6b along the southern border, close to two full zones of difference within one state, and that spread changes what a sensible tomato plan looks like far more than most gardeners expect from a single state's page. A gardener in the Upper Peninsula is working with a meaningfully shorter and cooler season than one in the southeast corner near Detroit, even though both are reading the same statewide averages.
The practical answer is not a different tomato so much as a different level of insurance: Upper Peninsula and northern Lower Peninsula gardeners do better starting transplants indoors a couple of weeks earlier than a seed packet's general guidance suggests and keeping a length of row cover on hand for a cold snap in early summer, something a southern Michigan garden rarely needs to worry about once the plant is established.
Staking decides how much of a short season you actually use
A tomato left to sprawl on the ground uses a meaningful share of its own growing season just fighting rot and slug damage on fruit touching wet soil, which is a cost a shorter northern Michigan season can afford even less than a longer one further south. Staking or caging every plant keeps foliage and fruit up off the ground where air actually moves around it, and that alone cuts down the leaf-wetness window that both early and late blight depend on to get started.
Prune the suckers, the shoots that emerge in the crook between the main stem and a leaf branch, on a staked plant regularly through the season; removing them redirects the plant's energy into the fruit already set rather than into new foliage that a shorter growing season may not have time to fully use before a fall frost ends things.
Hornworm feeding sign shows up before the worm does
The tomato hornworm's green coloring blends into tomato foliage well enough that most gardeners spot the damage before they spot the caterpillar itself: chewed, sometimes fully stripped stems and dark, pellet-shaped droppings scattered on the leaves and soil directly below a feeding site. Checking that dropping trail is a faster way to locate the worm than scanning leaf by leaf, since it points almost straight up at the branch doing the damage.
Hand-picking is genuinely the standard control for a home planting, and it works because hornworms are large, slow, and easy to spot once you know where to look; a worm carrying small white cocoons on its back is host to a parasitic wasp and should be left in place, since those wasps do more long-term hornworm control across a Michigan garden than any single afternoon of hand-picking can.
In Michigan: watch for
The pests that find tomatoes here.
A middle-length season, about 156 frost-free days, means tomato, slicing overlaps tomato hornworm for a stretch each summer. Check plants every week or two and treat early.
Big green caterpillars strip leaves and leave black droppings.
Organic fix: Handpick at dusk; spray Bt on the young ones.
Clusters on new growth, sticky leaves, curling tips.
Organic fix: Blast with water, then insecticidal soap or neem.
Dark spots with concentric rings, starting on the lowest, oldest leaves.
Organic fix: Remove affected leaves, mulch to stop soil splash, space for airflow.
Greasy, water-soaked blotches in cool, wet spells. No rings, and not bottom-up.
Organic fix: Pull infected plants fast, keep leaves dry, use neem as a preventive.
Septoria leaf spot
Many small tan spots with dark brown edges, low leaves first, no rings inside.
Organic fix: Strip the lowest leaves, mulch against soil splash, stake for airflow.
Your season math: Michigan gives tomatoes about 156 frost-free days, and it needs roughly 73 days to a first harvest. It's a one-planting crop, so time that single sowing well.
Planting tomatoes in Michigan: questions
When should I plant tomatoes in Michigan?+
In a typical Michigan year, sow tomatoes or set out transplants between May 12 to Jul 12, keyed to the state's median last frost around May 5. Your exact dates shift with your ZIP code and microclimate.
When do I start tomatoes seeds indoors in Michigan?+
Start seeds inside about 6 weeks before set-out: roughly Mar 31 to May 31 for a typical Michigan season.
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 tomatoes 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.