Rockville, Maryland, sits in USDA hardiness zone 7b — a zone band wide enough that plant choice, not possibility, is the interesting question.
These conditions suit cabbage, prickly pear, california poppy, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Rockville, 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 Rockville 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 Rockville — soil, climate, flood, and parcel records. How we handle your address.
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Rockville — the short answer
Rockville, Maryland: USDA zone 7b, about 230 days between hard freezes, across 9K acres of city.
- USDA zone
- 7b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~230
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 9K 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 7b is Rockville's average, not your lot's — a low corner or a tree line moves it. Against Rockville's 230-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rockville
Each reading below is measured for Rockville itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRockville runs about 230 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredRockville sits in USDA hardiness zone 7b.
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 Rockville is in
Rockville sits in the Northern Piedmont — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Rockville's own centroid rather than borrowed from Montgomery County.
What Grows in Rockville
Every plant below cleared Rockville's own zone 7b and its 230-day season. Each card opens that plant's Maryland profile. How we score.
Is it too late to plant in Rockville?
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 26; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 26 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 11 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Documented around Rockville
Spotted lanternfly documented 2 miles from Rockville, first recorded 2018. What to watch for.
What's on the federal record near Rockville
Closest first, within ~10 miles of Rockville. Listing isn't leaking, and distance isn't exposure.
- Coakley Williams ConstructionUnderground Storage Tanks · 850 ft
- SIR SPEEDY PRINTINGBrownfields · 900 ft
- Kimmel PropertiesUnderground Storage Tanks · 950 ft
- Rockville AssociatesUnderground Storage Tanks · 950 ft
- ROCKVILLE CENTER CLEANERSBrownfields · 1100 ft
- 26637 Sun Petro, LLCUnderground Storage Tanks · 1200 ft
- CENTER CLNRSBrownfields · 1200 ft
- PRINT SHOP CITY OF ROCKVILLE GOVTBrownfields · 1200 ft
- EXXONBrownfields · 1200 ft
- Snowden Funeral Home, P.A.Underground Storage Tanks · 1400 ft
- Rockville City HallUnderground Storage Tanks · 1400 ft
- Emergency Communications CenterUnderground Storage Tanks · 1500 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Rockville'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 Rockville.
Total Sites
2,313
within ~10 miles of Rockville
Risk Level
Elevated
Highest-severity
19 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Rockville
Severity Distribution
within ~10 miles of Rockville
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Rockville
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 Rockville average
Your land is one point inside Rockville
Everything above resolves to Rockville as a whole — one PHZM band and one 28°F frost record, read across 9K 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 city 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 Rockville Average
Rockville Average
- ●USDA Zones 7b, averaged across Rockville
- ●One soil character for all of Rockville
- ●Frost dates read at Rockville's scale: Mar 26 to Nov 11
YOUR Parcel
- ✓Your exact zone, not Rockville's 7b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rockville
Pull a site-specific report for your exact address in Rockville, Maryland — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rockville averages can't show:
We read public map data around Rockville — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rockville average
How we know this about Rockville
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Rockville’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 city grain anywhere on this page — there is no city-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 Rockville
When does frost risk typically end in Rockville?
The last hard freeze (28°F) in Rockville typically lands around Mar 26, 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 16.
When is the first frost in Rockville?
The first hard freeze (28°F) in Rockville typically arrives around Nov 11, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 28, so the watching starts about Oct 12 — about 230 days after the spring freeze cleared.
How long is the growing season in Rockville?
Measured between 28°F hard freezes, Rockville sees about 230 frost-free days — roughly Mar 26 through Nov 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 16 to Oct 28, about 195 days.
Is the soil safe to grow vegetables in Rockville?
The federal record around Rockville is a meaningful one — 2,313 documented sites, mostly Underground Storage Tanks entries (1,100), the nearest Underground Storage Tanks record about 0.2 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 Rockville?
From about Oct 12 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 Nov 11 (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 Nov 11. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Rockville's scale — its 7b band and its 230-day season. Your yard writes its own version of Rockville'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 Rockville’s own scale
7 of the readings below were taken at Rockville's own scale — its own ~230-day season between 28°F freezes, the 8,683 acres it covers and 2,313 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Rockville's own USDA hardiness band, zones 7bUSDA PHZM 2023
- Rockville's own 28°F hard-freeze dates, about Mar 26 and Nov 11 and the ~230-day span between themNOAA 1991–2020 Climate Normals
- 2,313 documented contamination sites on the federal record near Rockville, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Rockville's boundary and the 8,683 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7b and a ~230-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rockville's own centroid, the Northern PiedmontUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Rockvillelydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Rockville's 8,683 acres read through its county's SSURGO summaryfrom Montgomery County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Montgomery 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 Montgomery County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Rockville's 8,683 acreswhy one lot differs from the next →
- Which side of Rockville you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 8,683 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 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 Rockville-wide figureread your own land →
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