Unlikely — Zone Mismatch
sea hibiscus (zones 10-12) does not overlap with Maryland's zone range (5b-8a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Sea Hibiscus is hardy to zone 10, and the warmest ground in Maryland is zone 8 — 2 zones short. Planted in open ground it will not survive a Maryland winter. To grow it here, grow sea hibiscus 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 10-12 (plant) against 6-8 (Maryland). 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.
Maryland 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 sea hibiscus against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Sea Hibiscus Needs
- USDA Zones: 10-12
- Frost-Free Days: 270+
- Sun: Full Sun
Maryland Has
- USDA Zones: 5b-8a
- Last Hard Freeze (28°F): Mar 18 - Mar 29
- First Hard Freeze (28°F): Nov 11 - Nov 27
- Annual Rainfall: 36-48 inches
- Common Soils: Silt loam, Clay, Sandy loam (Eastern Shore)
Plant Zone Range (zones 10-12)
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 Sea Hibiscus in Maryland
The frost window
Across Maryland, the last spring hard freeze (28°F) clears between Mar 18 and Mar 29, and the first fall hard freeze lands between Nov 11 and Nov 27 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 227-day window you can count on — up to 254 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
Maryland runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for sea hibiscus, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether sea hibiscus is a permanent planting or a replant-every-spring crop for you turns on your own zone within Maryland; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Garrett 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 sea hibiscus does not survive a Maryland 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 Maryland under protection.
Frost-free days
Sea Hibiscus wants 270+ frost-free days; a typical Maryland site sees ~238 (NOAA Regional Climate Centers ACIS, 1991-2020) — 32 days short of what it needs. A typical Maryland 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
Sea Hibiscus likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Maryland's silt loam and clay — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 7 — worth knowing before you decide whether a Maryland soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Maryland 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 16.1% of Maryland as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Sea Hibiscus sits mid-range for drought tolerance, so either extreme can 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. Maryland soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Sea Hibiscus in Maryland — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 10-12 (USDA PLANTS Database)
- State Zones: 5b-8a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 18 - Mar 29 to Nov 11 - Nov 27 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Sea Hibiscus in Maryland
Zone compatibility tells you about winter cold survival — but Maryland growers also need to think about:
Heavy Piedmont clay drains poorly
Humidity and heat in summer promote disease
Deer pressure in suburban areas is extreme
Growing sea hibiscus here specifically
Sea Hibiscus rates to USDA zones 10–12 and is hardy to about 50°F, but cold isn't the risk in Maryland — wet is: with roughly 16.1% of its soils poorly-drained (SSURGO), soggy ground rots the crown.
Give sea hibiscus a raised bed or mounded row with coarse amendment so its crown never sit wet. How to handle it →
What to actually do about these — and the constraints that apply to every Maryland grower, not just sea hibiscus — is covered on the Maryland growing guide.
Timing shifts within Maryland
Maryland isn't one climate. In Garrett County, the last hard freeze (28°F) holds until about Apr 22 — roughly 29 days later than the recorded state median — so plant sea hibiscus to your county's window, not the statewide date.
Sea Hibiscus needs about 270 days of frost-free season to complete its cycle. 1 of Maryland’s 24 counties give it that outright. The tightest that does is Talbot County at 270 frost-free days — 0 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Maryland’s 24 counties the frost-free season runs from 190 days in Garrett County to 270 days in Talbot County — a spread of 80 days, which is why a single statewide planting date misleads. The median Maryland county sees 238 frost-free days, which is 32 days short of what sea hibiscus needs — so on a typical Maryland 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"). Sea Hibiscus's 270-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
Sea Hibiscus draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, sea hibiscus can only work that bloom inside Maryland's frost window — roughly 238 days, opening after the last 28°F freeze (Mar 18 - Mar 29) and closing at the first (Nov 11 - Nov 27), per NOAA Regional Climate Centers ACIS, 1991-2020.
Maryland Cooperative Extension
For Maryland-specific cultivar recommendations, planting calendars, and pest pressure for sea hibiscus, the canonical source is University of Maryland Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Sea Hibiscus native to Maryland?
No — the USDA PLANTS Database lists Sea Hibiscus as introduced rather than native in the Lower 48, so it is not part of Maryland's native flora. It grows here as a garden plant; pairing it with a few Maryland natives keeps local pollinators fed too.
Looking for plants that belong here? The Maryland 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 Sea Hibiscus in Maryland
When can I plant Sea Hibiscus in Maryland?
Maryland's last spring hard freeze (28°F) clears between Mar 18 and Mar 29, and the first fall hard freeze lands between Nov 11 and Nov 27 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Sea Hibiscus, so this page does not state whether it overwinters in Maryland 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 Sea Hibiscus grown in across Maryland?
Maryland spans USDA hardiness zones 5b-8a (USDA ARS PHZM 2023). Sea Hibiscus carries a range of zones 10-12, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Maryland site have?
A typical Maryland site sees ~238 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Sea Hibiscus needs 270+ 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 Garrett, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Sea Hibiscus native to Maryland?
No — the USDA PLANTS Database lists Sea Hibiscus as introduced rather than native in the Lower 48, so it is not part of Maryland's native flora. It grows here as a garden plant; pairing it with a few Maryland natives keeps local pollinators fed too.
How should I amend the soil for Sea Hibiscus in Maryland?
Sea Hibiscus prefers pH 5.5-7.5 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Maryland soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Sea Hibiscus actually grow on my specific land in Maryland?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores sea hibiscus 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 Maryland
State-level data is a sketch. Your Growable Ground report scores sea hibiscus against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Maryland sea hibiscus averages can't show:
We read public map data around Maryland — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Maryland sea hibiscus average
Explore More
Growing guides for sea hibiscus
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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