Unlikely — Zone Mismatch
swamp mahogany (zones 9-11) does not overlap with Kentucky's zone range (6a-7b). 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 Kentucky is zone 7 — 2 zones short. Planted in open ground it will not survive a Kentucky winter. To grow it here, grow swamp mahogany 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 9-11 (plant) against 6-7 (Kentucky). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['earth_sheltered'] (+2.5 zones) via api/fast_sections.py Unlock Engine v2.
Swamp Mahogany in Kentucky — the short answer
Swamp Mahogany in Kentucky: hardy in zones 9–11, full sun.
- Plant zones
- 9-11
- Rated hardy to zone 9 by Cal Poly SelecTree; USDA PLANTS Database lists 16 °F, converted to zone 9a, checked Oct 2026. Ceiling: our plant database.
- Kentucky zones
- 6a-7b
- USDA PHZM 2023
- Frost window
- Mar 27 - Apr 2 – Nov 4 - Nov 10
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 195 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.
Kentucky spans zones 6a-7b, 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.
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
Kentucky is not one climate
Kentucky’s winter-low ladder runs across 120 counties, from zone 6.5 in Anderson County to zone 7.5 in Lyon County. That is 10°F between the two counties’ average coldest night — the difference between swamp mahogany overwintering in the ground and coming under cover.
The middle half of 120 counties runs 6.5–7 zones, with a median of 7 zones — a 1-zone span end to end.
Measured across 120 Kentucky 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 Swamp Mahogany Stands in Kentucky
Swamp Mahogany is rated for zones 9–11 — a cold floor USDA puts at 20 to 30°F. No Kentucky 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 Kentucky winters, not about swamp mahogany.
Below the zone 9 floor
120 counties
- Anderson County · zone 6b
- Bath County · zone 6b
- Boone County · zone 6b
3 of 120 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
Swamp Mahogany Needs
- USDA Zones: 9-11
- Sun: Full Sun
- Mature size: 160 ft tall
- Drought tolerance: Low
Kentucky Has
- USDA Zones: 6a-7b
- Last Hard Freeze (28°F): Mar 27 - Apr 2
- First Hard Freeze (28°F): Nov 4 - Nov 10
- Annual Rainfall: 42-52 inches
- Common Soils: Silt loam, Clay loam, Limestone-derived
Plant Zone Range (zones 9-11)
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 Swamp Mahogany in Kentucky
The frost window
Across Kentucky, the last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Nov 4 and Nov 10 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 216-day window you can count on — up to 228 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
Kentucky runs as cold as USDA zone 6, 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 Kentucky; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Greenup 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
Swamp Mahogany likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Kentucky'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 Kentucky 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 Kentucky site is heavier clay or sits in a low spot, a raised bed lifts the roots above wet ground, or work in compost.
Your land, not the state average
Kentucky's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Swamp Mahogany needs about 59 inches of workable depth, so it is that horizon — not the surface — you are testing for. That map unit, not the state average, decides how swamp mahogany performs.
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. Kentucky soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Swamp Mahogany in Kentucky
Zone compatibility tells you about winter cold survival — but Kentucky growers also need to think about:
Heavy clay soils in the Bluegrass region
High humidity promotes fungal diseases
Karst topography creates drainage unpredictability
Growing swamp mahogany here specifically
Kentucky's soils run mostly silt loam (Alfisols), and whether that suits swamp mahogany's pH 5.5–7.5 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward swamp mahogany's 5.5–7.5 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Kentucky grower, not just swamp mahogany — is covered on the Kentucky growing guide.
Timing shifts within Kentucky
Kentucky isn't one climate. In Greenup County, the last hard freeze (28°F) holds until about Apr 13 — roughly 13 days later than the recorded state median — so plant swamp mahogany 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 Kentucky Swamp Mahogany Is Zone-Hardy
Swamp Mahogany is rated for USDA zones 9–11. No Kentucky county reaches it. Even Lyon County, the state’s mildest winter at zone 7b, sits below the plant’s zone 9 floor — so in open ground this one needs winter protection here, or a container that comes under cover.
Across those 120 counties Kentucky’s winter-low ladder runs from zone 6b in Anderson County to zone 7b in Lyon County — 1 USDA zone of spread, which is 10°F between the two counties’ average coldest night of the year. None of that range reaches the band swamp mahogany needs, so here the statewide answer really is the answer.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. Swamp Mahogany’s zone 9–11 band: Rated hardy to zone 9 by Cal Poly SelecTree; USDA PLANTS Database lists 16 °F, converted to zone 9a, checked Oct 2026. Ceiling: our plant database.. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Swamp Mahogany draws honeybees and native bees (high value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, swamp mahogany can only work that bloom inside Kentucky's frost window — roughly 221 days, opening after the last 28°F freeze (Mar 27 - Apr 2) and closing at the first (Nov 4 - Nov 10), per NOAA Regional Climate Centers ACIS, 1991-2020. Pollinator value: We haven't confirmed this against a published source yet.
Good to Know Before You Plant Swamp Mahogany
Swamp Mahogany is listed as toxic to dogs, cats (leaves) at a moderate level. We haven't confirmed this against a published source yet. Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Kentucky Cooperative Extension
For Kentucky-specific cultivar recommendations, planting calendars, and pest pressure for swamp mahogany, the canonical source is University of Kentucky Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Swamp Mahogany native to Kentucky?
No — the USDA PLANTS Database lists Swamp Mahogany as introduced rather than native in the Lower 48, so it is not part of Kentucky's native flora. It grows here as a garden plant; pairing it with a few Kentucky natives keeps local pollinators fed too.
Looking for plants that belong here? The Kentucky growing guide lists plants that USDA PLANTS records growing in Kentucky and that Kew and NatureServe Explorer both list in its native range, leaving out any that NatureServe flags as exotic there or that our audit holds.
State records: USDA PLANTS Database state-distribution data (presence, not state-level nativity), accessed 2026-10-19.
Common Questions About Growing Swamp Mahogany in Kentucky
When can I plant Swamp Mahogany in Kentucky?
Kentucky's last spring hard freeze (28°F) clears between Mar 27 and Apr 2, and the first fall hard freeze lands between Nov 4 and Nov 10 (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 Kentucky 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 Kentucky?
Kentucky spans USDA hardiness zones 6a-7b (USDA ARS PHZM 2023). Swamp Mahogany is listed for zones 9-11, which do not overlap them, so there is no zone in Kentucky where this page can call outdoor growing reliable. A parcel report resolves your own address's zone.
How many frost-free days does a typical Kentucky site have?
A typical Kentucky site sees ~221 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 Greenup, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Swamp Mahogany native to Kentucky?
No — the USDA PLANTS Database lists Swamp Mahogany as introduced rather than native in the Lower 48, so it is not part of Kentucky's native flora. It grows here as a garden plant; pairing it with a few Kentucky natives keeps local pollinators fed too.
How should I amend the soil for Swamp Mahogany in Kentucky?
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 Kentucky 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 Kentucky?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores swamp mahogany against your address's mapped soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Kentucky
State-level data is a sketch. Your Growable Ground report scores swamp mahogany against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Kentucky swamp mahogany averages can't show:
We read public map data around Kentucky — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kentucky swamp mahogany average
Explore More
Growing guides for swamp mahogany
Explore Kentucky county by county
Kentucky carries 120 counties with their own USDA zone — a sample of the growing pages for swamp mahogany there:
Where else swamp mahogany grows
Swamp Mahogany's zone band crosses state lines — these are the states closest to Kentucky 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 Kentucky
Kentucky 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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