St. Leonard, Maryland, sits in USDA hardiness zone 8a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Well-matched crops include cabbage, fig, california poppy, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in St. Leonard, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single St. Leonard lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around St. Leonard — soil, climate, flood, and parcel records. How we handle your address.
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St. Leonard — the short answer
St. Leonard, Maryland: USDA zone 8a, about 264 days between hard freezes, across 1K acres of town.
- USDA zone
- 8a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Dec 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~264
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 1K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 8a is St. Leonard's average, not your lot's — a low corner or a tree line moves it. Against St. Leonard's 264-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in St. Leonard
Each reading below is measured for St. Leonard itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSt. Leonard runs about 264 days between hard freezes — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSt. Leonard sits in USDA hardiness zone 8a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country St. Leonard is in
St. Leonard sits in the Southeastern Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at St. Leonard's own centroid rather than borrowed from Calvert County.
What Grows in St. Leonard
Every plant below cleared St. Leonard's own zone 8a and its 264-day season. Each card opens that plant's Maryland profile. How we score.
Is it too late to plant in St. Leonard?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Feb 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 1 — long-season crops need about 90 days of runway, quick greens only 30. With almost year-round growing weather, timing is about heat and rainfall more than frost — some bench is always in play.
Documented around St. Leonard
Spotted lanternfly documented 6 miles from St. Leonard, first recorded 2019. What to watch for.
What's on the federal record near St. Leonard
Closest first, within ~10 miles of St. Leonard. Listing isn't leaking, and distance isn't exposure.
- CA Ec 3Nitrate · 0.5 mi
- Chesapeake Flea MarketUnderground Storage Tanks · 0.5 mi
- Boyles TavernUnderground Storage Tanks · 0.6 mi
- St. Leonard FastopUnderground Storage Tanks · 0.6 mi
- St. Leonard's Garage (Formerly Buehler's Exxon)Underground Storage Tanks · 0.6 mi
- Weems Texaco ServiceUnderground Storage Tanks · 0.6 mi
- St. Leonard's Fire DepartmentUnderground Storage Tanks · 0.6 mi
- St. Leonard's SunocoUnderground Storage Tanks · 0.6 mi
- CA Ed 33Nitrate · 1.0 mi
- Norwood V. MarshallUnderground Storage Tanks · 1.2 mi
- Flagf Harbor Yacht HavenUnderground Storage Tanks · 1.3 mi
- CA Ed 19Nitrate · 1.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from St. Leonard's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near St. Leonard.
Sources Checked
within ~10 miles of St. Leonard
Severity Distribution
within ~10 miles of St. Leonard
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around St. Leonard, two things run higher than the national average within ~10 miles of St. Leonard — Nitrate (132 sites) and PFAS (3 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in St. Leonard
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the St. Leonard average
Your land is one point inside St. Leonard
Everything above resolves to St. Leonard as a whole — one PHZM band and one 28°F frost record, read across 1K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the St. Leonard Average
St. Leonard Average
- ●USDA Zones 8a, averaged across St. Leonard
- ●One soil character for all of St. Leonard
- ●Frost dates read at St. Leonard's scale: Mar 12 to Dec 1
YOUR Parcel
- ✓Your exact zone, not St. Leonard's 8a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in St. Leonard
Pull a site-specific report for your exact address in St. Leonard, Maryland — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that St. Leonard averages can't show:
We read public map data around St. Leonard — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the St. Leonard average
How we know this about St. Leonard
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at St. Leonard’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about St. Leonard
When does frost risk typically end in St. Leonard?
The last hard freeze (28°F) in St. Leonard typically lands around Mar 12, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 2.
When is the first frost in St. Leonard?
The first hard freeze (28°F) in St. Leonard typically arrives around Dec 1, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 17, so the watching starts about Nov 1 — about 264 days after the spring freeze cleared.
How long is the growing season in St. Leonard?
Measured between 28°F hard freezes, St. Leonard sees about 264 frost-free days — roughly Mar 12 through Dec 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 2 to Nov 17, about 229 days.
Is the soil safe to grow vegetables in St. Leonard?
The federal record around St. Leonard is a meaningful one — 335 documented sites, mostly Underground Storage Tanks entries (154), the nearest Nitrate record about 0.5 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in St. Leonard?
From about Nov 1 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Dec 1 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Dec 1. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at St. Leonard's scale — its 8a band and its 264-day season. Your yard writes its own version of St. Leonard's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at St. Leonard’s own scale
7 of the readings below were taken at St. Leonard's own scale — its own ~264-day season between 28°F freezes, the 1,462 acres it covers and 335 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- St. Leonard's own USDA hardiness band, zones 8aUSDA PHZM 2023
- St. Leonard's own 28°F hard-freeze dates, about Mar 12 and Dec 1 and the ~264-day span between themNOAA 1991–2020 Climate Normals
- 335 documented contamination sites on the federal record near St. Leonard, the closest Nitrate record about 0.5 miles out from the town centreFederal environmental registers
- St. Leonard's boundary and the 1,462 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8a and a ~264-day seasonGrowable Ground crop-matching engine
- The ecoregion at St. Leonard's own centroid, the Southeastern PlainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of St. Leonardlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so St. Leonard's 1,462 acres read through its county's SSURGO summaryfrom Calvert County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Calvert County
- The growing challenges every Maryland grower plans around — written at state scale, so they stay on the state guidefrom Maryland
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Calvert County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among St. Leonard's 1,462 acreswhy one lot differs from the next →
- Which side of St. Leonard you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,462 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.5 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any St. Leonard-wide figureread your own land →
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