Unlikely — Zone Mismatch
swamp mahogany (zones 9-11) does not overlap with Missouri's zone range (5b-8a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Swamp Mahogany is hardy to zone 9, and the warmest ground in Missouri is zone 7 — 2 zones short. Planted in open ground it will not survive a Missouri winter. To grow it here, grow swamp mahogany under glass — a greenhouse is the only lift this wide the engine models.
A greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 9-11 (plant) against 5-7 (Missouri). Lift modeled by crop_engine Sprint 20B effective_zone_modifier (+2 zones) via api/fast_sections.py Unlock Engine v2.
Your yard isn't the whole zone.
Missouri spans zones 5b-8a, 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 swamp mahogany against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Swamp Mahogany Needs
- USDA Zones: 9-11
- Frost-Free Days: 240+
- Sun: Full Sun
- Mature size: 160 ft tall
- Drought tolerance: Low
Missouri Has
- USDA Zones: 5b-8a
- Last Hard Freeze (28°F): Mar 27 - Apr 2
- First Hard Freeze (28°F): Oct 31 - Nov 7
- Annual Rainfall: 34-50 inches
- Common Soils: Silt loam, Clay loam, Loess
Plant Zone Range (zones 9-11)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Swamp Mahogany in Missouri
The frost window
Across Missouri, the last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Oct 31 and Nov 7 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 212-day window you can count on — up to 225 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
Missouri runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for swamp mahogany, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether swamp mahogany is a permanent planting or a replant-every-spring crop for you turns on your own zone within Missouri; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Crawford County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says swamp mahogany does not survive a Missouri winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on Missouri under protection.
Frost-free days
Swamp Mahogany wants 240+ frost-free days; a typical Missouri site sees ~219 (NOAA Regional Climate Centers ACIS, 1991-2020) — 21 days short of what it needs. A typical Missouri season does not carry this crop to harvest outdoors, and a gap that size is not one an earlier sowing date or a faster cultivar closes; growing it here means growing it under cover.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Swamp Mahogany likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Missouri's silt loam and clay loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 6.5 — worth knowing before you decide whether a Missouri soil test result is a problem or just a number. Drainage matters: this plant wants poorly (saturated >50% of year), well (dry spells). If your Missouri site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 31.8% of Missouri as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Swamp Mahogany has low drought tolerance, so it is the fast-draining end that will cost you — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Missouri soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Swamp Mahogany in Missouri — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 9-11 (USDA PLANTS Database)
- State Zones: 5b-8a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 27 - Apr 2 to Oct 31 - Nov 7 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Swamp Mahogany in Missouri
Zone compatibility tells you about winter cold survival — but Missouri growers also need to think about:
Highly variable weather with late frosts and early heat
Heavy clay soils in many regions
Ozark soils are thin and rocky
Growing swamp mahogany here specifically
Swamp Mahogany needs sharp drainage and sends deep roots hardy to about 41°F; in Missouri, about 31.8% of soils are poorly-drained (SSURGO), and standing water is what actually kills it.
Build swamp mahogany up on a coarse, free-draining mound so its crown never sit in saturated soil. How to handle it →
What to actually do about these — and the constraints that apply to every Missouri grower, not just swamp mahogany — is covered on the Missouri growing guide.
Timing shifts within Missouri
Missouri isn't one climate. In Crawford County, the last hard freeze (28°F) holds until about Apr 10 — roughly 12 days later than the recorded state median — so plant swamp mahogany to your county's window, not the statewide date.
Swamp Mahogany needs about 240 days of frost-free season to complete its cycle. 7 of Missouri’s 115 counties give it that outright. The tightest that does is Mississippi County at 240 frost-free days — 0 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Missouri’s 115 counties the frost-free season runs from 192 days in Crawford County to 258 days in Pemiscot County — a spread of 66 days, which is why a single statewide planting date misleads. The median Missouri county sees 219 frost-free days, which is 21 days short of what swamp mahogany needs — so on a typical Missouri parcel this is a transplant-or-protect crop, not a direct-sow one.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Swamp Mahogany's 240-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Swamp Mahogany draws honeybees and native bees (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, swamp mahogany can only work that bloom inside Missouri's frost window — roughly 219 days, opening after the last 28°F freeze (Mar 27 - Apr 2) and closing at the first (Oct 31 - Nov 7), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant Swamp Mahogany
Swamp Mahogany is listed as toxic to dogs, cats (leaves) at a moderate level (ASPCA). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Missouri Cooperative Extension
For Missouri-specific cultivar recommendations, planting calendars, and pest pressure for swamp mahogany, the canonical source is MU Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Swamp Mahogany native to Missouri?
No — the USDA PLANTS Database lists Swamp Mahogany as introduced rather than native in the Lower 48, so it is not part of Missouri's native flora. It grows here as a garden plant; pairing it with a few Missouri natives keeps local pollinators fed too.
Looking for plants that belong here? The Missouri 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 Swamp Mahogany in Missouri
When can I plant Swamp Mahogany in Missouri?
Missouri's last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Oct 31 and Nov 7 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Swamp Mahogany, so this page does not state whether it overwinters in Missouri 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 Swamp Mahogany grown in across Missouri?
Missouri spans USDA hardiness zones 5b-8a (USDA ARS PHZM 2023). Swamp Mahogany carries a range of zones 9-11, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Missouri site have?
A typical Missouri site sees ~219 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Swamp Mahogany needs 240+ 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 Crawford, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Swamp Mahogany native to Missouri?
No — the USDA PLANTS Database lists Swamp Mahogany as introduced rather than native in the Lower 48, so it is not part of Missouri's native flora. It grows here as a garden plant; pairing it with a few Missouri natives keeps local pollinators fed too.
How should I amend the soil for Swamp Mahogany in Missouri?
Swamp Mahogany prefers pH 5.5-7.5 and poorly (saturated >50% of year), well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Missouri soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Swamp Mahogany actually grow on my specific land in Missouri?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores swamp mahogany 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 Missouri
State-level data is a sketch. Your Growable Ground report scores swamp mahogany against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Missouri swamp mahogany averages can't show:
We read public map data around Missouri — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Missouri swamp mahogany average
Explore More
Growing guides for swamp mahogany
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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