Why, Arizona, 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.
Well-matched crops include jalapeno, palo verde, date palm, and prickly pear, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Why, 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 Why 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 Why — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Why — the short answer
Why, Arizona: USDA zone 9b, about 313 days between hard freezes, across 6K acres of town.
- USDA zone
- 9b
- 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
- 6K 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 9b is Why's average, not your lot's — a low corner or a tree line moves it. Against Why's 313-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Why
Each reading below is measured for Why itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsWhy runs about 313 days between hard freezes (read from Pima County, the closest normal to Why) — 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
MeasuredWhy 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 Why is in
Why sits in the Sonoran Basin and Range — EPA Level III, inside the wider North American Deserts. That is read at Why's own centroid rather than borrowed from Pima County.
What Grows in Why
Plants matched to Why's USDA zones 9b, ordered by how much hardiness margin each has here — the ones with room to spare at both ends of this town's band lead. Each links to its full growing profile.
Is it too late to plant in Why?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. 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.
What's on the federal record near Why
Closest first, within ~10 miles of Why. Listing isn't leaking, and distance isn't exposure.
- SHELLUnderground Storage Tanks · 0.5 mi
- WHY CHEVRON # 315Underground Storage Tanks · 0.6 mi
- TEXACOUnderground Storage Tanks · 0.7 mi
- THE WHY NOT TRAVEL STOREUnderground Storage Tanks · 0.7 mi
- 80806Nitrate · 0.7 mi
- USHSA - CUSTOMS & BORDER PROTECTIONUnderground Storage Tanks · 1.1 mi
- C-14-04 09CADNitrate · 3.7 mi
- C-14-04 09DBBNitrate · 3.8 mi
- Gunsight MineMining · 4.4 mi
- Morning Star MineMining · 4.5 mi
- Surprise MineMining · 4.7 mi
- Crescent Et Al GroupMining · 4.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Why'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 Why.
Severity Distribution
within ~10 miles of Why
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Why, two things run higher than the national average within ~10 miles of Why — Mining (24 sites) and Nitrate (14 sites). 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.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Why
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 Why average
Your land is one point inside Why
Everything above resolves to Why as a whole — one PHZM band, read across 6K 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 Why Average
Why Average
- ●USDA Zones 9b, averaged across Why
- ●One soil character for all of Why
- ●Frost dates read at Why's scale: Feb 3 to Dec 13
YOUR Parcel
- ✓Your exact zone, not Why's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Why
Pull a site-specific report for your exact address in Why, Arizona — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Why averages can't show:
We read public map data around Why — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Why average
How we know this about Why
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 Why
When does frost risk typically end in Why?
The last hard freeze (28°F) in Why 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 Why?
The first hard freeze (28°F) in Why 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 Why?
Measured between 28°F hard freezes, Why 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 Why?
The federal record around Why is a meaningful one — 43 documented sites, mostly Mining entries (24), the nearest Underground Storage Tanks record about 0.5 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 Why?
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 Why's scale — its 9b band and its 313-day season. Your yard writes its own version of Why'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 Why’s own scale
4 of the readings below were taken at Why's own scale — the 5,732 acres it covers and 43 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Why's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 43 documented contamination sites on the federal record near Why, the closest Underground Storage Tanks record about 0.5 miles out from the town centreFederal environmental registers
- Why's boundary and the 5,732 acres inside itUS Census TIGER/Line 2025
- The ecoregion at Why's own centroid, the Sonoran Basin and RangeUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Why 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 Why's 5,732 acres read through its county's SSURGO summaryfrom Pima County
- The candidate plant list — Arizona's curated set, filtered to this zone band and re-ordered by how much margin each has herefrom Arizona
- 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 Why's 5,732 acreswhy one lot differs from the next →
- Which side of Why you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 5,732 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.5 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 Why-wide figureread your own land →
More in Arizona
Nearby growing guides