Waltham, Massachusetts, sits in USDA hardiness zone 6b — 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, hazelnut, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
You’re in Greater Boston
The state's dense urban core, where growing means raised beds, community plots, and back-lot kitchen gardens more than open field. A long, mild season for the region — but city soil is the thing to know before you dig.
Even in Waltham, 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 Waltham 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 Waltham — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Waltham — the short answer
Waltham, Massachusetts: USDA zone 6b, about 203 days between hard freezes, across 8K acres of city.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~203
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 8K 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 6b is Waltham's average, not your lot's — a low corner or a tree line moves it. Against Waltham's 203-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Waltham
Each reading below is measured for Waltham itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWaltham runs about 203 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
MeasuredWaltham sits in USDA hardiness zone 6b.
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 Waltham is in
Waltham sits in the Northeastern Coastal Zone — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Waltham's own centroid rather than borrowed from Middlesex County.
What Grows in Waltham
Every plant below cleared Waltham's own zone 6b and its 203-day season. Each card opens that plant's Massachusetts profile. How we score.
Is it too late to plant in Waltham?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 9 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 29 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Documented around Waltham
Spotted lanternfly documented 4 miles from Waltham, first recorded 2023. What to watch for.
What's on the federal record near Waltham
Closest first, within ~10 miles of Waltham. Listing isn't leaking, and distance isn't exposure.
- R J CINCOTTA CO INCUnderground Storage Tanks · 1900 ft
- CHAPEL HILL CHAUNCY HALL SCHOOLBrownfields · 1900 ft
- IDEAL CONCRETE BLOCK COUnderground Storage Tanks · 2000 ft
- IDEAL CONCRETE BLOCK COBrownfields · 2200 ft
- OREILLY AUTO PARTS 4725Brownfields · 2300 ft
- S J DAGOSTINO INCUnderground Storage Tanks · 2300 ft
- SULLIVAN TIRE CO INCBrownfields · 2400 ft
- LYONS TIRE & AUTO CENTERSUnderground Storage Tanks · 2400 ft
- WALTHAM SCHOOL DEPARTMENTBrownfields · 2500 ft
- LENZA OIL TERMINALSUnderground Storage Tanks · 2500 ft
- MONRO 431Brownfields · 2500 ft
- TAYLOR AND MURPHYUnderground Storage Tanks · 0.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Waltham'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 Waltham.
Sources Checked
within ~10 miles of Waltham
Severity Distribution
within ~10 miles of Waltham
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Waltham, Brownfields runs higher than the national average — 4,746 sites within ~10 miles of Waltham. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Waltham
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 Waltham average
Your land is one point inside Waltham
Everything above resolves to Waltham as a whole — one PHZM band and one 28°F frost record, read across 8K 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 Waltham Average
Waltham Average
- ●USDA Zones 6b, averaged across Waltham
- ●One soil character for all of Waltham
- ●Frost dates read at Waltham's scale: Apr 9 to Oct 29
YOUR Parcel
- ✓Your exact zone, not Waltham's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Waltham
Pull a site-specific report for your exact address in Waltham, Massachusetts — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Waltham averages can't show:
We read public map data around Waltham — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Waltham average
How we know this about Waltham
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 Waltham’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 Waltham
When does frost risk typically end in Waltham?
The last hard freeze (28°F) in Waltham typically lands around Apr 9, 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 30.
When is the first frost in Waltham?
The first hard freeze (28°F) in Waltham typically arrives around Oct 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 15, so the watching starts about Sep 29 — about 203 days after the spring freeze cleared.
How long is the growing season in Waltham?
Measured between 28°F hard freezes, Waltham sees about 203 frost-free days — roughly Apr 9 through Oct 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 30 to Oct 15, about 168 days.
Is the soil safe to grow vegetables in Waltham?
The federal record around Waltham runs heavier than most — 6,672 documented sites, mostly Brownfields entries (4,746), the nearest Underground Storage Tanks record about 0.4 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Waltham?
From about Sep 29 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 Oct 29 (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 Oct 29. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Waltham's scale — its 6b band and its 203-day season. Your yard writes its own version of Waltham'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 Waltham’s own scale
7 of the readings below were taken at Waltham's own scale — its own ~203-day season between 28°F freezes, the 8,157 acres it covers and 6,672 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Waltham's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Waltham's own 28°F hard-freeze dates, about Apr 9 and Oct 29 and the ~203-day span between themNOAA 1991–2020 Climate Normals
- 6,672 documented contamination sites on the federal record near Waltham, the closest Underground Storage Tanks record about 0.4 miles out from the town centreFederal environmental registers
- Waltham's boundary and the 8,157 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~203-day seasonGrowable Ground crop-matching engine
- The ecoregion at Waltham's own centroid, the Northeastern Coastal ZoneUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Walthamlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Waltham's 8,157 acres read through its county's SSURGO summaryfrom Middlesex County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Middlesex County
- The growing challenges every Massachusetts grower plans around — written at state scale, so they stay on the state guidefrom Massachusetts
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Middlesex County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Waltham's 8,157 acreswhy one lot differs from the next →
- Which side of Waltham you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 8,157 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.4 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 Waltham-wide figureread your own land →
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