Unlikely — Zone Mismatch
ironwood (zones 10-13) does not overlap with Michigan's zone range (4a-7a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Ironwood is hardy to zone 10, and the warmest ground in Michigan is zone 7 — 2 zones short. Planted in open ground it will not survive a Michigan winter. To grow it here, grow ironwood in an earth-sheltered greenhouse — its modeled 2.5-zone lift covers this gap.
An earth-sheltered greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 10-13 (plant) against 4-7 (Michigan). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['earth_sheltered'] (+2.5 zones) via api/fast_sections.py Unlock Engine v2.
Ironwood in Michigan — the short answer
Ironwood in Michigan: hardy in zones 10–13, full sun.
- Plant zones
- 10-13
- Hardy to zone 9b: USDA PLANTS Database lists 22 °F, converted to zone 9b, checked Oct 2026. The source rates it slightly hardier than our range. Ceiling: our plant database.
- Michigan zones
- 4a-7a
- USDA PHZM 2023
- Frost window
- Apr 19 - May 8 – Oct 12 - Oct 31
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 126 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Michigan spans zones 4a-7a, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score ironwood against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your parcel report in seconds — read in full free for your first 14 days
Michigan is not one climate
Michigan’s winter-low ladder runs across 83 counties, from zone 4 in Gogebic County to zone 7 in Allegan County. That is 30°F between the two counties’ average coldest night — the difference between ironwood overwintering in the ground and coming under cover.
The middle half of 83 counties runs 5–6 zones, with a median of 6 zones — a 3-zone span end to end.
Measured across 83 Michigan counties. USDA PHZM 2023, per county. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where Ironwood Stands in Michigan
Ironwood is rated for zones 10–13 — a cold floor USDA puts at 30 to 40°F. No Michigan county sits inside it, so in open ground this is a grown-under-cover plant here rather than a bed plant — which is a statement about Michigan winters, not about ironwood.
Below the zone 10 floor
83 counties
- Gogebic County · zone 4a
- Iron County · zone 4a
- Baraga County · zone 4b
3 of 83 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Zone Comparison
Ironwood Needs
- USDA Zones: 10-13
- Sun: Full Sun
- Drought tolerance: High
Michigan Has
- USDA Zones: 4a-7a
- Last Hard Freeze (28°F): Apr 19 - May 8
- First Hard Freeze (28°F): Oct 12 - Oct 31
- Annual Rainfall: 28-38 inches
- Common Soils: Sandy loam, Clay loam, Muck
Plant Zone Range (zones 10-13)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Ironwood in Michigan
The frost window
Across Michigan, the last spring hard freeze (28°F) clears between Apr 19 and May 8, and the first fall hard freeze lands between Oct 12 and Oct 31 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 157-day window you can count on — up to 195 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Winter standing
Michigan runs as cold as USDA zone 4, and no sourced winter-hardiness floor is on record for ironwood, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether ironwood is a permanent planting or a replant-every-spring crop for you turns on your own zone within Michigan; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Luce County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Soil + Drainage Fit
Ironwood likes near-neutral soil (pH 6.8-8.6). That's the common-ground band across Michigan's sandy loam and clay loam — a soil test confirms it for your site.
Your land, not the state average
Michigan soil pH runs about 5.6–6.3, and that sits below ironwood's tolerated 6.8–8.6, so the typical Michigan parcel needs lime before it will perform. SSURGO maps it swinging by full points parcel to parcel, so your map unit, not the state number, decides whether ironwood needs lime or sulfur.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Michigan soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Ironwood in Michigan
Zone compatibility tells you about winter cold survival — but Michigan growers also need to think about:
Lake effect weather creates highly localized microclimates
Short northern season (100-120 frost-free days in UP)
Sandy soils in western MI drain too quickly
Growing ironwood here specifically
Ironwood wants soil pH 6.8–8.6, but Michigan's soils run acidic (SSURGO maps a dominant pH near 5.9) — below its range, nutrients lock up and growth stalls.
Test your soil and lime to raise pH into ironwood's 6.8–8.6 range before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Michigan grower, not just ironwood — is covered on the Michigan growing guide.
Timing shifts within Michigan
Michigan isn't one climate. In Luce County, the last hard freeze (28°F) holds until about May 22 — roughly 27 days later than the recorded state median — so plant ironwood to your county's window, not the statewide date.
County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). A parcel report resolves your address's own frost dates.
Where in Michigan Ironwood Is Zone-Hardy
Ironwood is rated for USDA zones 10–13. No Michigan county reaches it. Even Allegan County, the state’s mildest winter at zone 7a, sits below the plant’s zone 10 floor — so in open ground this one needs winter protection here, or a container that comes under cover.
Across those 83 counties Michigan’s winter-low ladder runs from zone 4a in Gogebic County to zone 7a in Allegan County — 3 USDA zones of spread, which is 30°F between the two counties’ average coldest night of the year. None of that range reaches the band ironwood needs, so here the statewide answer really is the answer.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. Ironwood’s zone 10–13 band: Hardy to zone 9b: USDA PLANTS Database lists 22 °F, converted to zone 9b, checked Oct 2026. The source rates it slightly hardier than our range. Ceiling: our plant database.. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Michigan Cooperative Extension
For Michigan-specific cultivar recommendations, planting calendars, and pest pressure for ironwood, the canonical source is MSU Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Ironwood native to Michigan?
Ironwood is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Michigan. It can still earn a place in a Michigan garden — the zone comparison above tells you whether it will thrive.
Looking for plants that belong here? The Michigan growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Ironwood in Michigan
When can I plant Ironwood in Michigan?
Michigan's last spring hard freeze (28°F) clears between Apr 19 and May 8, and the first fall hard freeze lands between Oct 12 and Oct 31 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Ironwood, so this page does not state whether it overwinters in Michigan and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Ironwood grown in across Michigan?
Michigan spans USDA hardiness zones 4a-7a (USDA ARS PHZM 2023). Ironwood carries a range of zones 10-13, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Michigan site have?
A typical Michigan site sees ~186 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Ironwood needs 365+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Luce, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Ironwood native to Michigan?
Ironwood is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Michigan. It can still earn a place in a Michigan garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Ironwood in Michigan?
Ironwood prefers pH 6.8-8.6 (USDA PLANTS). That sits in the common-ground band across Michigan soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Ironwood actually grow on my specific land in Michigan?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores ironwood against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Michigan
State-level data is a sketch. Your Growable Ground report scores ironwood against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Michigan ironwood averages can't show:
We read public map data around Michigan — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Michigan ironwood average
Explore More
Growing guides for ironwood
Explore Michigan county by county
Michigan carries 83 counties with their own USDA zone — a sample of the growing pages for ironwood there:
Where else ironwood grows
Ironwood's zone band crosses state lines — these are the states closest to Michigan in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Michigan
Michigan has a growing page for 889 plants — a rotating sample of the rest of the shelf.
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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