Lake Riverside, California, sits in USDA hardiness zone 9a — 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 artichoke, fig, california poppy, and cabbage; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Lake Riverside, 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 Lake Riverside 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 Lake Riverside — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Lake Riverside — the short answer
Lake Riverside, California: USDA zone 9a, about 303 days between hard freezes, across 5K acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 13
- Riverside County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 13
- Riverside County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~303
- Riverside County normal — NOAA 1991–2020, nearest to this town
- Town area
- 5K 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 Riverside County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Lake Riverside's average, not your lot's — a low corner or a tree line moves it. Against Lake Riverside's 303-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Lake Riverside
Each reading below is measured for Lake Riverside itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsLake Riverside runs about 303 days between hard freezes (read from Riverside County, the closest normal to Lake Riverside) — 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
MeasuredLake Riverside 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 Lake Riverside is in
Lake Riverside sits in the Southern California Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Lake Riverside's own centroid, and it is not what its county reads: Riverside County is mostly Sonoran Basin and Range. The wider page above you is answering a different question about different ground.
What Grows in Lake Riverside
Every plant below cleared Lake Riverside's own zone 9a and its 303-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Lake Riverside?
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 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 13 — 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 Lake Riverside
Closest first, within ~10 miles of Lake Riverside. Listing isn't leaking, and distance isn't exposure.
- 007S002E32F001SNitrate · 0.7 mi
- LAKE RIVERSIDE ESTATES COMMUNITY ASSN.Brownfields · 0.8 mi
- 008S002E05C001SNitrate · 1.0 mi
- ERIC J HALEY DBA HERITAGE WELL SERVICEBrownfields · 1.3 mi
- 007S002E32J001SNitrate · 1.4 mi
- 007S002E33N001SNitrate · 1.4 mi
- 008S002E05A001SNitrate · 1.4 mi
- AT&T MOBILITYBrownfields · 1.9 mi
- 007S002E33C001SNitrate · 1.9 mi
- 007S001E24Q001SNitrate · 1.9 mi
- 007S001E26K001SNitrate · 2.3 mi
- RCIT - LAKE RIVERSIDEBrownfields · 2.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Lake Riverside'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 Lake Riverside.
Total Sites
309
within ~10 miles of Lake Riverside
Risk Level
Elevated
Highest-severity
26 brownfield sites
Sources Checked
within ~10 miles of Lake Riverside
Severity Distribution
within ~10 miles of Lake Riverside
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Lake Riverside, Nitrate runs higher than the national average — 280 sites within ~10 miles of Lake Riverside. That's not a problem with your land — it's information about it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Lake Riverside
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 Lake Riverside average
Your land is one point inside Lake Riverside
Everything above resolves to Lake Riverside as a whole — one PHZM band, read across 5K acres, with hard-freeze dates borrowed from Riverside 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 Lake Riverside Average
Lake Riverside Average
- ●USDA Zones 9a, averaged across Lake Riverside
- ●One soil character for all of Lake Riverside
- ●Frost dates read at Lake Riverside's scale: Feb 13 to Dec 13
YOUR Parcel
- ✓Your exact zone, not Lake Riverside's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Lake Riverside
Pull a site-specific report for your exact address in Lake Riverside, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Lake Riverside averages can't show:
We read public map data around Lake Riverside — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Lake Riverside average
How we know this about Lake Riverside
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 Riverside 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 Lake Riverside
When does frost risk typically end in Lake Riverside?
The last hard freeze (28°F) in Lake Riverside typically lands around Feb 13, 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 Mar 6.
When is the first frost in Lake Riverside?
The first hard freeze (28°F) in Lake Riverside typically arrives around Dec 13, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 29, so the watching starts about Nov 13 — about 303 days after the spring freeze cleared.
How long is the growing season in Lake Riverside?
Measured between 28°F hard freezes, Lake Riverside sees about 303 frost-free days — roughly Feb 13 through Dec 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 6 to Nov 29, about 268 days.
Is the soil safe to grow vegetables in Lake Riverside?
The federal record around Lake Riverside is a meaningful one — 309 documented sites, mostly Nitrate entries (280), the nearest Nitrate 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 I protect my plants from frost in Lake Riverside?
From about Nov 13 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 13 (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 13. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Lake Riverside's scale — its 9a band and its 303-day season. Your yard writes its own version of Lake Riverside'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 Lake Riverside’s own scale
5 of the readings below were taken at Lake Riverside's own scale — the 4,668 acres it covers and 309 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Lake Riverside's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 309 documented contamination sites on the federal record near Lake Riverside, the closest Nitrate record about 0.7 miles out from the town centreFederal environmental registers
- Lake Riverside's boundary and the 4,668 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~303-day seasonGrowable Ground crop-matching engine
- Lake Riverside sits in the Southern California Mountains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Lake Riverside has no normal of its own, so its county's is the closest measured readfrom Riverside County
- Soil character — no town-scale survey exists, so Lake Riverside's 4,668 acres read through its county's SSURGO summaryfrom Riverside County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Riverside 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 Riverside County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Lake Riverside's 4,668 acreswhy one lot differs from the next →
- Which side of Lake Riverside you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,668 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate 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 Lake Riverside-wide figureread your own land →
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