Solano County, in California, sits in USDA hardiness zone 9b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Reliable performers under these conditions include okra, meyer lemon, california poppy, and artichoke; what your own ground favors still comes down to its soil, sun, and drainage.
Solano County lies within the California Delta — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Solano County holds more than one microclimate.
Soils and elevations shift across Solano County, so your frost dates and drainage aren't the county average. 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 Solano County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Solano County — the short answer
Solano County, California: USDA zone 9b, about 335 days between hard freezes, across 526K acres.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 15
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 16
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~335
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 526K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 9b is Solano County's average, not your lot's — a low corner or a tree line moves it. Against Solano County's 335-day season, see what your own ground reads.
Heat and winter chill in Solano County
Across a year, Solano County accumulates about 4,035 growing degree days above 50°F, about 278 more than the middle California county — ahead of 31 of California’s 57 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Winter banks about 1,064 hours below 45°F, 123 fewer than the California middle of 1,187. Chill is what tells a fruit tree its dormancy is over, and it is set by climate rather than by anything you can build.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Solano County
Across Solano County, the ground is predominantly Alfisols, where San Ysidro, Capay, and Dibble are the most extensive named soil series. The soil is generally well drained with a clay surface. Topsoil pH runs about 6.1–7.3, neutral. Rainfall drains through hydrologic group D soils.
Soil order
Alfisols
Drainage
Well drained
Hydric soils
23%
Soil still varies lot by lot — soil types explained.
How the ground varies across Solano County
The USDA soil survey maps 40% of Solano County as well drained — but another 50% drains differently: 23% moderately well drained, 13% poorly drained.
San Ysidro is the most extensive named soil at 8% of mapped acres, then Capay (7%) and Dibble (7%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Solano County
Each reading below is measured for Solano County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Solano County are well drained, in hydrologic group D — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Solano County runs about pH 6.1–7.3, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Wet ground
MeasuredAbout 23% of Solano County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredSolano County runs about 335 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
The kind of country Solano County is in
Solano County spans 2 EPA Level III ecoregions — Central California Valley (55%) and Central California Foothills and Coastal Mountains (45%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Solano County
We scored all 1,086 plants against Solano County's own USDA zone 9b and its own 335-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's California profile.
Is it too late to plant in Solano County?
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 15 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 16 — 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.
Documented around Solano County
- monarch butterfly277 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Solano County
USGS estimates 99,984 lb of Glyphosate on Solano County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (25,515 lb) and Metolachlor-s (18,288 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Solano County — and how to grow with it.
We checked the federal record across Solano County — 2,348 documented sites across 7 of the 9 source types we track.
The most significant on record: 7 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Solano County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Solano County
Closest first, across Solano County. Listing isn't leaking, and distance isn't exposure.
- CALIFORNIA WATER SERVICE CO.-TRAVIS AFBPFAS · 1500 ft
- US DOD USAF TRAVIS AFBBrownfields · 2000 ft
- US DOD USAF TRAVIS AFBToxics Release Inventory · 2000 ft
- TRAVIS AIR FORCE BASESuperfund · 2100 ft
- FIRESTONE COMPLETE AUTO CARE # 3590Brownfields · 0.6 mi
- Travis Express SouthUnderground Storage Tanks · 0.7 mi
- Travis Express NorthUnderground Storage Tanks · 0.7 mi
- FAIRFIELD ARMORYBrownfields · 0.8 mi
- Fuel Hydrant Area GUnderground Storage Tanks · 0.9 mi
- Fuel Hydrant Area HUnderground Storage Tanks · 0.9 mi
- Fuel Hydrant Area CUnderground Storage Tanks · 0.9 mi
- Base Motor PoolUnderground Storage Tanks · 0.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Solano County'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 Solano County.
Sources Checked
across Solano County
Severity Distribution
across Solano County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Solano County, Brownfields runs higher than the national average — 2,018 sites across Solano County. That's not a problem with your land — it's information about 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 Solano County
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 Solano County average
Your land is one point inside Solano County
Everything above resolves to Solano County as a whole — one PHZM band and one county frost record, read across 526K 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 county 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 county average.
Your Lot vs the Solano County Average
Solano County Average
- ●USDA Zones 9b, averaged across Solano County
- ●One soil character for all of Solano County
- ●Frost dates read at Solano County's scale: Jan 15 to Dec 16
YOUR Parcel
- ✓Your exact zone, not Solano County's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Solano County
Pull a site-specific report for your exact address in Solano County, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Solano County averages can't show:
We read public map data around Solano County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Solano County average
How we know this about Solano County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Solano County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Solano County
When does frost risk typically end in Solano County?
The last hard freeze (28°F) in Solano County typically lands around Jan 15, 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 5.
How long is the growing season in Solano County?
Measured between 28°F hard freezes, Solano County sees about 335 frost-free days — roughly Jan 15 through Dec 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 5 to Dec 2, about 300 days.
Is the soil safe to grow vegetables in Solano County?
The federal record around Solano County runs heavier than most — 2,348 documented sites, mostly Brownfields entries (2,018), the nearest PFAS record about 0.3 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.
Everything above is measured at Solano County's scale — its 9b band and its 335-day season. Your yard writes its own version of Solano County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads California's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Solano County’s own scale
9 of the readings below were taken at Solano County's own scale — its own ~335-day span between 28°F freezes, the 3 most extensive soil series mapped here and 2,348 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Solano County's own USDA hardiness band, zones 9bUSDA PHZM 2023
- Solano County's own 28°F hard-freeze dates and its ~335-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Solano CountyUSDA NRCS SSURGO
- 2,348 documented contamination sites inside the county boundary, distance-sorted from its center — the closest PFAS record about 0.3 miles outFederal environmental registers
- Solano County's boundary and the 525,912 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~335-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Solano County spans, Central California Valley the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Solano County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Solano County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every California grower plans around — written at state scale, so they stay on the state guidefrom California
What this page can’t tell you
- How the season shifts across Solano County — the ~335 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Solano County's 525,912 acreswhy one lot differs from the next →
- Which of those 2,348 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Solano Countyread your own land →