Robinson Mill, California, sits in USDA hardiness zone 9a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Reliable performers under these conditions include tomato, artichoke, fig, and california poppy; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Robinson Mill, 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 Robinson Mill 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 Robinson Mill — soil, climate, flood, and parcel records. How we handle your address.
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Robinson Mill — the short answer
Robinson Mill, California: USDA zone 9a, about 332 days between hard freezes, across 843 acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 19
- Butte County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 17
- Butte County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~332
- Butte County normal — NOAA 1991–2020, nearest to this town
- Town area
- 843 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Butte County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Robinson Mill's average, not your lot's — a low corner or a tree line moves it. Against Robinson Mill's 332-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Robinson Mill
Each reading below is measured for Robinson Mill itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsRobinson Mill runs about 332 days between hard freezes (read from Butte County, the closest normal to Robinson Mill) — 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
MeasuredRobinson Mill sits in USDA hardiness zone 9a.
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 Robinson Mill is in
Robinson Mill sits in the Sierra Nevada — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Robinson Mill's own centroid, and it is not what its county reads: Butte County is mostly Central California Valley. The wider page above you is answering a different question about different ground.
What Grows in Robinson Mill
Plants matched to Robinson Mill's USDA zones 9a, ordered by how much hardiness margin each has here — the ones with room to spare at both ends of this town's band lead. Each links to its full growing profile.
Is it too late to plant in Robinson Mill?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Jan 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 19 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 17 — long-season crops need about 90 days of runway, quick greens only 30. In a climate this gentle, “too late” hardly applies — the question becomes which crops prefer the cooler months ahead.
What's on the federal record near Robinson Mill
Closest first, within ~10 miles of Robinson Mill. Listing isn't leaking, and distance isn't exposure.
- 019N006E16C001MNitrate · 1.9 mi
- SUTTER MEDICAL FOUNDATION DBA SUTTER NORTH MEDICAL FOUNDATIONBrownfields · 2.6 mi
- Gold Eagle Market #1Underground Storage Tanks · 2.8 mi
- GOLD EAGLE MARKET #1Brownfields · 2.8 mi
- ESCHEMAN CONSTRUCTIONBrownfields · 3.0 mi
- 019N006E26J001MNitrate · 3.3 mi
- SOUTH FORK POWER PROJECTBrownfields · 3.5 mi
- New Oregon, Forty-NineMining · 3.8 mi
- New OregonMining · 3.8 mi
- NEW CINGULAR WIRELESS PCS LLCBrownfields · 4.0 mi
- Gold Bank Consolidated QuartzMining · 4.2 mi
- Forbestown Consolidated Gold MinesMining · 4.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Robinson Mill'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 Robinson Mill.
Total Sites
94
within ~10 miles of Robinson Mill
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Robinson Mill
Severity Distribution
within ~10 miles of Robinson Mill
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Robinson Mill, two things run higher than the national average within ~10 miles of Robinson Mill — Mining (29 sites) and PFAS (3 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Robinson Mill
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 Robinson Mill average
Your land is one point inside Robinson Mill
Everything above resolves to Robinson Mill as a whole — one PHZM band, read across 843 acres, with hard-freeze dates borrowed from Butte County’s record because no 30-year normal resolves at this town’s own centroid. 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 Robinson Mill Average
Robinson Mill Average
- ●USDA Zones 9a, averaged across Robinson Mill
- ●One soil character for all of Robinson Mill
- ●Frost dates read at Robinson Mill's scale: Jan 19 to Dec 17
YOUR Parcel
- ✓Your exact zone, not Robinson Mill's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Robinson Mill
Pull a site-specific report for your exact address in Robinson Mill, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Robinson Mill averages can't show:
We read public map data around Robinson Mill — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Robinson Mill average
How we know this about Robinson Mill
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 Butte County’s record, because none resolves here; 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 Robinson Mill
When does frost risk typically end in Robinson Mill?
The last hard freeze (28°F) in Robinson Mill typically lands around Jan 19, 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 Feb 9.
When is the first frost in Robinson Mill?
The first hard freeze (28°F) in Robinson Mill typically arrives around Dec 17, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Dec 3, so the watching starts about Nov 17 — about 332 days after the spring freeze cleared.
How long is the growing season in Robinson Mill?
Measured between 28°F hard freezes, Robinson Mill sees about 332 frost-free days — roughly Jan 19 through Dec 17, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 9 to Dec 3, about 297 days.
Is the soil safe to grow vegetables in Robinson Mill?
The federal record around Robinson Mill is a meaningful one — 94 documented sites, mostly Brownfields entries (31), the nearest Nitrate record about 1.9 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 Robinson Mill?
From about Nov 17 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 17 (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 17. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Robinson Mill's scale — its 9a band and its 332-day season. Your yard writes its own version of Robinson Mill'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 Robinson Mill’s own scale
4 of the readings below were taken at Robinson Mill's own scale — the 843 acres it covers and 94 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Robinson Mill's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 94 documented contamination sites on the federal record near Robinson Mill, the closest Nitrate record about 1.9 miles out from the town centreFederal environmental registers
- Robinson Mill's boundary and the 843 acres inside itUS Census TIGER/Line 2025
- Robinson Mill sits in the Sierra Nevada — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Robinson Mill has no normal of its own, so its county's is the closest measured readfrom Butte County
- Soil character — no town-scale survey exists, so Robinson Mill's 843 acres read through its county's SSURGO summaryfrom Butte County
- The candidate plant list — California's curated set, filtered to this zone band and re-ordered by how much margin each has herefrom California
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Butte 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 Butte County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Robinson Mill's 843 acreswhy one lot differs from the next →
- Which side of Robinson Mill you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 843 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 1.9 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 Robinson Mill-wide figureread your own land →