Rincon Valley, Arizona, 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 Rincon Valley, 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 Rincon Valley 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 Rincon Valley — soil, climate, flood, and parcel records. How we handle your address.
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Rincon Valley — the short answer
Rincon Valley, Arizona: USDA zone 9a, about 313 days between hard freezes, across 16K acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 3
- Pima County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 13
- Pima County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~313
- Pima County normal — NOAA 1991–2020, nearest to this town
- Town area
- 16K 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 Pima County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Rincon Valley's average, not your lot's — a low corner or a tree line moves it. Against Rincon Valley's 313-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rincon Valley
Each reading below is measured for Rincon Valley itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsRincon Valley runs about 313 days between hard freezes (read from Pima County, the closest normal to Rincon Valley) — 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
MeasuredRincon Valley 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 Rincon Valley is in
Rincon Valley sits in the Sonoran Basin and Range — EPA Level III, inside the wider North American Deserts. That is read at Rincon Valley's own centroid rather than borrowed from Pima County.
What Grows in Rincon Valley
Every plant below cleared Rincon Valley's own zone 9a and its 313-day season. Each card opens that plant's Arizona profile. How we score.
Is it too late to plant in Rincon Valley?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Jan 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 3 (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. In a climate this gentle, “too late” hardly applies — the question becomes which crops prefer the cooler months ahead.
Documented around Rincon Valley
Survey cells within 31 miles of Rincon Valley checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 384 miles off. What to watch for.
What's on the federal record near Rincon Valley
Closest first, within ~10 miles of Rincon Valley. Listing isn't leaking, and distance isn't exposure.
- D-15-16 34CBANitrate · 2.1 mi
- RINCON CREEK STOREUnderground Storage Tanks · 2.3 mi
- CPC SOUTHWEST MATERIALS VALENCIA PLANTToxics Release Inventory · 3.0 mi
- CALPORTLAND - VALENCIAUnderground Storage Tanks · 3.0 mi
- D-16-16 04DABNitrate · 3.0 mi
- BLACK ANGUS - POORMAN FACILITYToxics Release Inventory · 3.0 mi
- CALPORTLAND COMPANY POORMAN PLANTToxics Release Inventory · 3.0 mi
- UnknownMining · 3.1 mi
- Rincon Mtn GroupMining · 3.3 mi
- HENRY W JACKSONUnderground Storage Tanks · 4.2 mi
- SAFEWAY STORE 2809Brownfields · 4.2 mi
- SAFEWAY FUELING STATION #2809Underground Storage Tanks · 4.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Rincon Valley'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 Rincon Valley.
Total Sites
193
within ~10 miles of Rincon Valley
Risk Level
Elevated
Highest-severity
12 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Rincon Valley
Severity Distribution
within ~10 miles of Rincon Valley
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Rincon Valley, two things run higher than the national average within ~10 miles of Rincon Valley — PFAS (3 sites) and Nitrate (60 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Rincon Valley
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 Rincon Valley average
Your land is one point inside Rincon Valley
Everything above resolves to Rincon Valley as a whole — one PHZM band, read across 16K acres, with hard-freeze dates borrowed from Pima 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 Rincon Valley Average
Rincon Valley Average
- ●USDA Zones 9a, averaged across Rincon Valley
- ●One soil character for all of Rincon Valley
- ●Frost dates read at Rincon Valley's scale: Feb 3 to Dec 13
YOUR Parcel
- ✓Your exact zone, not Rincon Valley's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rincon Valley
Pull a site-specific report for your exact address in Rincon Valley, Arizona — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rincon Valley averages can't show:
We read public map data around Rincon Valley — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rincon Valley average
How we know this about Rincon Valley
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 Pima 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 Rincon Valley
When does frost risk typically end in Rincon Valley?
The last hard freeze (28°F) in Rincon Valley typically lands around Feb 3, 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 24.
When is the first frost in Rincon Valley?
The first hard freeze (28°F) in Rincon Valley 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 313 days after the spring freeze cleared.
How long is the growing season in Rincon Valley?
Measured between 28°F hard freezes, Rincon Valley sees about 313 frost-free days — roughly Feb 3 through Dec 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 24 to Nov 29, about 278 days.
Is the soil safe to grow vegetables in Rincon Valley?
The federal record around Rincon Valley is a meaningful one — 193 documented sites, mostly Underground Storage Tanks entries (64), the nearest Nitrate record about 2.1 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 Rincon Valley?
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 Rincon Valley's scale — its 9a band and its 313-day season. Your yard writes its own version of Rincon Valley'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 Rincon Valley’s own scale
6 of the readings below were taken at Rincon Valley's own scale — the 16,284 acres it covers and 193 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Rincon Valley's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 193 documented contamination sites on the federal record near Rincon Valley, the closest Nitrate record about 2.1 miles out from the town centreFederal environmental registers
- Rincon Valley's boundary and the 16,284 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~313-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rincon Valley's own centroid, the Sonoran Basin and RangeUS EPA Level III Ecoregions
- Lanternfly survey cells around Rincon Valley checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Rincon Valley has no normal of its own, so its county's is the closest measured readfrom Pima County
- Soil character — no town-scale survey exists, so Rincon Valley's 16,284 acres read through its county's SSURGO summaryfrom Pima County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Pima 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 Pima County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Rincon Valley's 16,284 acreswhy one lot differs from the next →
- Which side of Rincon Valley you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 16,284 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 2.1 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 Rincon Valley-wide figureread your own land →