Riverdale Park, California, sits in USDA hardiness zone 9b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
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.
Even in Riverdale Park, 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 Riverdale Park 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 Riverdale Park — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Riverdale Park — the short answer
Riverdale Park, California: USDA zone 9b, about 322 days between hard freezes, across 931 acres of town.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 22
- Stanislaus County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 10
- Stanislaus County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~322
- Stanislaus County normal — NOAA 1991–2020, nearest to this town
- Town area
- 931 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 Stanislaus County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9b is Riverdale Park's average, not your lot's — a low corner or a tree line moves it. Against Riverdale Park's 322-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Riverdale Park
Each reading below is measured for Riverdale Park itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsRiverdale Park runs about 322 days between hard freezes (read from Stanislaus County, the closest normal to Riverdale Park) — 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
MeasuredRiverdale Park sits in USDA hardiness zone 9b.
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 Riverdale Park is in
Riverdale Park sits in the Central California Valley — EPA Level III, inside the wider Mediterranean California. That is read at Riverdale Park's own centroid rather than borrowed from Stanislaus County.
What Grows in Riverdale Park
Every plant below cleared Riverdale Park's own zone 9b and its 322-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Riverdale Park?
Rarely: the season closes in stages, not all at once, and each stage has its crops. 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 22 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 10 — long-season crops need about 90 days of runway, quick greens only 30. With almost year-round growing weather, timing is about heat and rainfall more than frost — some bench is always in play.
What's on the federal record near Riverdale Park
Closest first, within ~10 miles of Riverdale Park. Listing isn't leaking, and distance isn't exposure.
- ACE AUTO WRECKERS INCBrownfields · 2200 ft
- 004S008E12E001MNitrate · 0.5 mi
- LOPES TRUCK SVC INCBrownfields · 0.5 mi
- BONZI SANITATION LANDFILL INCBrownfields · 0.5 mi
- BONZI SANITARY LANDFILLSuperfund · 0.5 mi
- MODESTO DISPOSAL SERVICEBrownfields · 0.6 mi
- MODESTO DISPOSAL SERVICESuperfund · 0.6 mi
- HOME CAR CAREBrownfields · 0.8 mi
- ORCHARD AG FARMS INCBrownfields · 0.9 mi
- 004S008E13G001MNitrate · 1.0 mi
- JACOBSON TRUCK & ENGINEBrownfields · 1.0 mi
- WILSON AUTO WRECKINGBrownfields · 1.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Riverdale Park'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 Riverdale Park.
Total Sites
2,241
within ~10 miles of Riverdale Park
Risk Level
Elevated
Highest-severity
9 Superfund sites
Sources Checked
within ~10 miles of Riverdale Park
Severity Distribution
within ~10 miles of Riverdale Park
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Riverdale Park, Brownfields runs higher than the national average — 1,576 sites within ~10 miles of Riverdale Park. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Riverdale Park
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 Riverdale Park average
Your land is one point inside Riverdale Park
Everything above resolves to Riverdale Park as a whole — one PHZM band, read across 931 acres, with hard-freeze dates borrowed from Stanislaus 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 Riverdale Park Average
Riverdale Park Average
- ●USDA Zones 9b, averaged across Riverdale Park
- ●One soil character for all of Riverdale Park
- ●Frost dates read at Riverdale Park's scale: Jan 22 to Dec 10
YOUR Parcel
- ✓Your exact zone, not Riverdale Park's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Riverdale Park
Pull a site-specific report for your exact address in Riverdale Park, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Riverdale Park averages can't show:
We read public map data around Riverdale Park — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Riverdale Park average
How we know this about Riverdale Park
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 Stanislaus 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 Riverdale Park
When does frost risk typically end in Riverdale Park?
The last hard freeze (28°F) in Riverdale Park typically lands around Jan 22, 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 12.
When is the first frost in Riverdale Park?
The first hard freeze (28°F) in Riverdale Park typically arrives around Dec 10, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 26, so the watching starts about Nov 10 — about 322 days after the spring freeze cleared.
How long is the growing season in Riverdale Park?
Measured between 28°F hard freezes, Riverdale Park sees about 322 frost-free days — roughly Jan 22 through Dec 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 12 to Nov 26, about 287 days.
Is the soil safe to grow vegetables in Riverdale Park?
The federal record around Riverdale Park is a meaningful one — 2,241 documented sites, mostly Brownfields entries (1,576), the nearest Brownfields record about 0.4 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 Riverdale Park?
From about Nov 10 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 10 (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 10. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Riverdale Park's scale — its 9b band and its 322-day season. Your yard writes its own version of Riverdale Park'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 Riverdale Park’s own scale
5 of the readings below were taken at Riverdale Park's own scale — the 931 acres it covers and 2,241 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Riverdale Park's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 2,241 documented contamination sites on the federal record near Riverdale Park, the closest Brownfields record about 0.4 miles out from the town centreFederal environmental registers
- Riverdale Park's boundary and the 931 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~322-day seasonGrowable Ground crop-matching engine
- The ecoregion at Riverdale Park's own centroid, the Central California ValleyUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Riverdale Park has no normal of its own, so its county's is the closest measured readfrom Stanislaus County
- Soil character — no town-scale survey exists, so Riverdale Park's 931 acres read through its county's SSURGO summaryfrom Stanislaus County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Stanislaus 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 Stanislaus County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Riverdale Park's 931 acreswhy one lot differs from the next →
- Which side of Riverdale Park you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 931 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields 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 Riverdale Park-wide figureread your own land →