Unlikely — Zone Mismatch
geranium (zones 10-11) does not overlap with Maryland's zone range (5b-8a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Geranium 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 geranium 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 10-11 (plant) against 6-8 (Maryland). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['earth_sheltered'] (+2.5 zones) via api/fast_sections.py Unlock Engine v2.
Geranium in Maryland — the short answer
Geranium in Maryland: hardy in zones 10–11, part sun, against a state median of ~238 frost-free days.
- Plant zones
- 10-11
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Maryland zones
- 5b-8a
- USDA PHZM 2023
- Frost window
- Mar 18 - Mar 29 – Nov 11 - Nov 27
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 190 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 95 days
- Growable Ground Plant Database
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.
Maryland spans zones 5b-8a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score geranium against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Maryland is not one climate
A single Maryland answer averages 24 counties whose growing seasons are 80 days apart — from 190 frost-free days in Garrett County to 270 in Talbot County. Which end of that your land sits nearer changes what geranium can finish before the first hard freeze.
The middle half of 24 counties runs 225–255 days, with a median of 237 days — a 80-day span end to end.
Measured across 24 Maryland counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. 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 Geranium Stands in Maryland
Geranium is rated for zones 10–11 — a cold floor USDA puts at 30 to 40°F. No Maryland 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 Maryland winters, not about geranium.
Below the zone 10 floor
24 counties
- Garrett County · zone 6a
- Allegany County · zone 7a
- Carroll County · zone 7a
3 of 24 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
Geranium Needs
- USDA Zones: 10-11
- Sun: Part Sun
- Mature size: 1.5 ft tall
- Picking window: ~150 days of harvest
- Drought tolerance: Medium
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 10-11)
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 Geranium 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.
When to start the seed
Those dates are when geranium goes out, not when it starts. It is sown under cover about 14 weeks ahead, so counting back from Maryland's late-side last freeze of Mar 29 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Days to maturity vs. the window
At 95 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 132 days to spare even in Maryland's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Garrett 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.
Growing Season Fit
The zone check says geranium 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.
Days to maturity
Geranium matures in ~95 days (Growable Ground Plant Database). A typical Maryland site has ~238 frost-free days, so plenty of room for a second succession.
Growing degree days
Geranium needs ~1000 GDD (base 50°F) to ripen. The state median runs ~3789 GDD (from PRISM 1991-2020 climate normals), so Maryland's typical season clears that easily.
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
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
Maryland's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for geranium is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how geranium 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. Maryland soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Geranium 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
What to actually do about these — and the constraints that apply to every Maryland grower, not just geranium — 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 geranium to your county's window, not the statewide date.
Geranium needs about 95 days of frost-free season from planting to harvest. Even Garrett County — Maryland’s shortest season at 190 frost-free days — clears that by 95 days, so season length isn’t the constraint anywhere in Maryland. What varies is your own parcel.
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, leaving geranium about 143 days of slack on a typical parcel — room for a second sowing where the season runs long.
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"). Geranium's 95-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Geranium draws honeybees and butterflies (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, geranium 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.
Good to Know Before You Plant Geranium
Geranium is listed as toxic to dogs, cats (all) at a mild level (ASPCA). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear. Worth knowing for placement: in Maryland this is a one-season plant and the first hard freeze (Nov 11 - Nov 27) takes it down, so the exposure above is a summer-long one rather than something standing in the bed all year.
Recommended Geranium Varieties for Maryland
Maryland publishes no state variety trial for geranium, so we won't invent a "best for Maryland" list. Choose types rated to your USDA hardiness zone (5b-8a), and confirm winter survival and drainage against your own parcel.
Maryland Cooperative Extension
For Maryland-specific cultivar recommendations, planting calendars, and pest pressure for geranium, the canonical source is University of Maryland Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Geranium in Maryland
When can I plant Geranium 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). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Geranium mature before first frost in Maryland?
Yes — Geranium matures in 95 days (Growable Ground Plant Database), and Maryland's dependable hard-freeze-free window runs 227 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 132 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Geranium grown in across Maryland?
Maryland spans USDA hardiness zones 5b-8a (USDA ARS PHZM 2023). Geranium carries a range of zones 10-11, 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). Geranium should be matched against that window, 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.
Will Geranium actually grow on my specific land in Maryland?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores geranium 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 geranium against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Maryland geranium 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 geranium average
Explore More
Growing guides for geranium
Explore Maryland county by county
Maryland carries 24 counties with their own USDA zone — a sample of the growing pages for geranium there:
Where else geranium grows
Geranium's zone band crosses state lines — these are the states closest to Maryland 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 Maryland
Maryland has a growing page for 1,020 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
Last updated: