Rio Rico, Arizona, sits in USDA hardiness zone 8b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Among the crops suited to this profile: cabbage, fig, california poppy, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Rio Rico, 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 Rio Rico 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 Rio Rico — soil, climate, flood, and parcel records. How we handle your address.
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Rio Rico — the short answer
Rio Rico, Arizona: USDA zone 8b, about 267 days between hard freezes, across 40K acres of town.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~267
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 40K 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 8b is Rio Rico's average, not your lot's — a low corner or a tree line moves it. Against Rio Rico's 267-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rio Rico
Each reading below is measured for Rio Rico itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRio Rico runs about 267 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
Winter hardiness
MeasuredRio Rico sits in USDA hardiness zone 8b.
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 Rio Rico is in
Rio Rico sits in the Madrean Archipelago — EPA Level III, inside the wider Southern Semi-arid Highlands. That is read at Rio Rico's own centroid rather than borrowed from Santa Cruz County.
What Grows in Rio Rico
Every plant below cleared Rio Rico's own zone 8b and its 267-day season. Each card opens that plant's Arizona profile. How we score.
Is it too late to plant in Rio Rico?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Feb 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 1 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 23 — long-season crops need about 90 days of runway, quick greens only 30. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
Documented around Rio Rico
Survey cells within 31 miles of Rio Rico checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 379 miles off. What to watch for.
What's on the federal record near Rio Rico
Closest first, within ~10 miles of Rio Rico. Listing isn't leaking, and distance isn't exposure.
- D-22-13 27AAB UNSURVNitrate · 0.7 mi
- LIBERTY WATER RIO RICOPFAS · 0.8 mi
- FAMILY DOLLAR #6848Brownfields · 1.3 mi
- SANTA CRUZ VALLEY UNIFIED SCHOOL DISTRICT #35 - BUS BARNUnderground Storage Tanks · 1.7 mi
- D-22-13 34ADD UNSURVNitrate · 1.9 mi
- Tubutana MineMining · 2.1 mi
- Tubuana MineMining · 2.1 mi
- GAS 4 LESSUnderground Storage Tanks · 2.1 mi
- CPC SOUTHWEST MATERIALS RIO RICO PLANTToxics Release Inventory · 2.4 mi
- RIO RICO SERVICE CENTER INCUnderground Storage Tanks · 2.5 mi
- GRG CONSTRUCTION - RIO RICO CBP & HMAP SITEBrownfields · 2.5 mi
- D-22-13 09C UNSURVNitrate · 2.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Rio Rico'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 Rio Rico.
Total Sites
132
within ~10 miles of Rio Rico
Risk Level
High
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Rio Rico
Severity Distribution
within ~10 miles of Rio Rico
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Rio Rico, Mining runs higher than the national average — 31 sites within ~10 miles of Rio Rico. That's not a problem with your land — it's information about 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.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Rio Rico
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 Rio Rico average
Your land is one point inside Rio Rico
Everything above resolves to Rio Rico as a whole — one PHZM band and one 28°F frost record, read across 40K 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 Rio Rico Average
Rio Rico Average
- ●USDA Zones 8b, averaged across Rio Rico
- ●One soil character for all of Rio Rico
- ●Frost dates read at Rio Rico's scale: Mar 1 to Nov 23
YOUR Parcel
- ✓Your exact zone, not Rio Rico's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rio Rico
Pull a site-specific report for your exact address in Rio Rico, Arizona — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rio Rico averages can't show:
We read public map data around Rio Rico — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rio Rico average
How we know this about Rio Rico
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 Rio Rico’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 Rio Rico
When does frost risk typically end in Rio Rico?
The last hard freeze (28°F) in Rio Rico typically lands around Mar 1, 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 22.
When is the first frost in Rio Rico?
The first hard freeze (28°F) in Rio Rico typically arrives around Nov 23, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 9, so the watching starts about Oct 24 — about 267 days after the spring freeze cleared.
How long is the growing season in Rio Rico?
Measured between 28°F hard freezes, Rio Rico sees about 267 frost-free days — roughly Mar 1 through Nov 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 22 to Nov 9, about 232 days.
Is the soil safe to grow vegetables in Rio Rico?
The federal record around Rio Rico runs heavier than most — 132 documented sites, mostly Underground Storage Tanks entries (38), the nearest Nitrate record about 0.7 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.
How do I protect my plants from frost in Rio Rico?
From about Oct 24 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 Nov 23 (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 Nov 23. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Rio Rico's scale — its 8b band and its 267-day season. Your yard writes its own version of Rio Rico'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 Rio Rico’s own scale
7 of the readings below were taken at Rio Rico's own scale — its own ~267-day season between 28°F freezes, the 40,375 acres it covers and 132 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Rio Rico's own USDA hardiness band, zones 8bUSDA PHZM 2023
- Rio Rico's own 28°F hard-freeze dates, about Mar 1 and Nov 23 and the ~267-day span between themNOAA 1991–2020 Climate Normals
- 132 documented contamination sites on the federal record near Rio Rico, the closest Nitrate record about 0.7 miles out from the town centreFederal environmental registers
- Rio Rico's boundary and the 40,375 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~267-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rio Rico's own centroid, the Madrean ArchipelagoUS EPA Level III Ecoregions
- Lanternfly survey cells around Rio Rico checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Rio Rico's 40,375 acres read through its county's SSURGO summaryfrom Santa Cruz County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Santa Cruz County
- The growing challenges every Arizona grower plans around — written at state scale, so they stay on the state guidefrom Arizona
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Santa Cruz County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Rio Rico's 40,375 acreswhy one lot differs from the next →
- Which side of Rio Rico you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 40,375 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 Rio Rico-wide figureread your own land →
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