Kirkwood, California, sits in USDA hardiness zone 6b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
A short list that earns its place here — cabbage, blackberry, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Kirkwood, 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 Kirkwood 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 Kirkwood — soil, climate, flood, and parcel records. How we handle your address.
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Kirkwood — the short answer
Kirkwood, California: USDA zone 6b, about 121 days between hard freezes, across 3K acres of town.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jun 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~121
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 3K 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 Kirkwood's average, not your lot's — a low corner or a tree line moves it. Against Kirkwood's 121-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Kirkwood
Each reading below is measured for Kirkwood itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredKirkwood runs about 121 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredKirkwood 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 Kirkwood is in
Kirkwood sits in the Sierra Nevada — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Kirkwood's own centroid rather than borrowed from Alpine County.
What Grows in Kirkwood
Every plant below cleared Kirkwood's own zone 6b and its 121-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Kirkwood?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around May 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jun 2 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 1 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.
What's on the federal record near Kirkwood
Closest first, within ~10 miles of Kirkwood. Listing isn't leaking, and distance isn't exposure.
- CAL TRANSBrownfields · 0.7 mi
- AT&T MOBILITYBrownfields · 0.7 mi
- KIRKWOOD MEADOWS PUBLIC UTILITY DISTRICTBrownfields · 0.9 mi
- KIRKWOOD MAINTENANCE SHOPBrownfields · 0.9 mi
- KIRKWOOD MEADOWS PUBLIC UTILITY DISTRICT MAINTENANCE BLDGBrownfields · 1.0 mi
- KIRKWOOD ASSOCIATES INCBrownfields · 1.3 mi
- Lost CabinMining · 2.2 mi
- Round TopMining · 3.0 mi
- SILVER LAKE PINES PUMP STATIONBrownfields · 3.3 mi
- EL DORADO IRRIGATION DISTRICTBrownfields · 4.2 mi
- KIRKWOOD MEADOWS PUBLIC UTILITY DISTRICTPFAS · 4.5 mi
- Alhambra MineMining · 5.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Kirkwood'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 Kirkwood.
Sources Checked
within ~10 miles of Kirkwood
Severity Distribution
within ~10 miles of Kirkwood
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Kirkwood, two things run higher than the national average within ~10 miles of Kirkwood — Mining (10 sites) and Brownfields (17 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Kirkwood
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 Kirkwood average
Your land is one point inside Kirkwood
Everything above resolves to Kirkwood as a whole — one PHZM band and one 28°F frost record, read across 3K 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 Kirkwood Average
Kirkwood Average
- ●USDA Zones 6b, averaged across Kirkwood
- ●One soil character for all of Kirkwood
- ●Frost dates read at Kirkwood's scale: Jun 2 to Oct 1
YOUR Parcel
- ✓Your exact zone, not Kirkwood's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Kirkwood
Pull a site-specific report for your exact address in Kirkwood, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Kirkwood averages can't show:
We read public map data around Kirkwood — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kirkwood average
How we know this about Kirkwood
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 Kirkwood’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 Kirkwood
When does frost risk typically end in Kirkwood?
The last hard freeze (28°F) in Kirkwood typically lands around Jun 2, 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 Jun 23.
When is the first frost in Kirkwood?
The first hard freeze (28°F) in Kirkwood typically arrives around Oct 1, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 17, so the watching starts about Sep 1 — about 121 days after the spring freeze cleared.
How long is the growing season in Kirkwood?
Measured between 28°F hard freezes, Kirkwood sees about 121 frost-free days — roughly Jun 2 through Oct 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 23 to Sep 17, about 86 days.
Is the soil safe to grow vegetables in Kirkwood?
The federal record around Kirkwood is a meaningful one — 34 documented sites, mostly Brownfields entries (17), the nearest Brownfields record about 0.7 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 gardeners stretch the season in Kirkwood?
With about 121 frost-free days between hard freezes, Kirkwood rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 149 to 177 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the Jun 2 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Kirkwood's scale — its 6b band and its 121-day season. Your yard writes its own version of Kirkwood'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 Kirkwood’s own scale
6 of the readings below were taken at Kirkwood's own scale — its own ~121-day season between 28°F freezes, the 2,790 acres it covers and 34 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Kirkwood's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Kirkwood's own 28°F hard-freeze dates, about Jun 2 and Oct 1 and the ~121-day span between themNOAA 1991–2020 Climate Normals
- 34 documented contamination sites on the federal record near Kirkwood, the closest Brownfields record about 0.7 miles out from the town centreFederal environmental registers
- Kirkwood's boundary and the 2,790 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~121-day seasonGrowable Ground crop-matching engine
- The ecoregion at Kirkwood's own centroid, the Sierra NevadaUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Kirkwood's 2,790 acres read through its county's SSURGO summaryfrom Alpine County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Alpine County
- The growing challenges every California grower plans around — written at state scale, so they stay on the state guidefrom California
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Alpine County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Kirkwood's 2,790 acreswhy one lot differs from the next →
- Which side of Kirkwood you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,790 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.7 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 Kirkwood-wide figureread your own land →