Summit, Arizona, sits in USDA hardiness zone 9b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Among the crops suited to this profile: jalapeno, palo verde, date palm, and prickly pear. The site-level story — soil, sun, drainage — decides the rest.
Even in Summit, 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 Summit 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 Summit — soil, climate, flood, and parcel records. How we handle your address.
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Summit — the short answer
Summit, Arizona: USDA zone 9b, about 313 days between hard freezes, across 2K 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
- 2K 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 Summit's average, not your lot's — a low corner or a tree line moves it. Against Summit's 313-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Summit
Each reading below is measured for Summit itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsSummit runs about 313 days between hard freezes (read from Pima County, the closest normal to Summit) — 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
MeasuredSummit 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 Summit is in
Summit sits in the Sonoran Basin and Range — EPA Level III, inside the wider North American Deserts. That is read at Summit's own centroid rather than borrowed from Pima County.
What Grows in Summit
Plants matched to Summit'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 Summit?
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. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
Documented around Summit
Survey cells within 31 miles of Summit checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 370 miles off. What to watch for.
What's on the federal record near Summit
Closest first, within ~10 miles of Summit. Listing isn't leaking, and distance isn't exposure.
- ANTONICK DRYWALL COUnderground Storage Tanks · 2500 ft
- D-16-14 06CDC2Nitrate · 2600 ft
- D-16-14 07BAD2Nitrate · 0.6 mi
- D-16-14S06CBANitrate · 0.7 mi
- D-16-14S06BCBNitrate · 0.8 mi
- D-16-14N06DCCNitrate · 0.9 mi
- CIRCLE K #2701140Underground Storage Tanks · 1.0 mi
- D-16-14 07DCB1Nitrate · 1.0 mi
- NOGALES HWY IRON & STEEL INCUnderground Storage Tanks · 1.4 mi
- MEXICO WAY MARKETUnderground Storage Tanks · 1.5 mi
- D-15-14 31CBBNitrate · 1.5 mi
- CHEVRON - MAUST CHEVRONUnderground Storage Tanks · 1.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Summit'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 Summit.
Sources Checked
within ~10 miles of Summit
Severity Distribution
within ~10 miles of Summit
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Summit, two things run higher than the national average within ~10 miles of Summit — Nitrate (380 sites) and Toxics Release Inventory (69 sites). 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.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Summit
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 Summit average
Your land is one point inside Summit
Everything above resolves to Summit as a whole — one PHZM band, read across 2K 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 Summit Average
Summit Average
- ●USDA Zones 9b, averaged across Summit
- ●One soil character for all of Summit
- ●Frost dates read at Summit's scale: Feb 3 to Dec 13
YOUR Parcel
- ✓Your exact zone, not Summit's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Summit
Pull a site-specific report for your exact address in Summit, Arizona — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Summit averages can't show:
We read public map data around Summit — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Summit average
How we know this about Summit
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 Summit
When does frost risk typically end in Summit?
The last hard freeze (28°F) in Summit 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 Summit?
The first hard freeze (28°F) in Summit 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 Summit?
Measured between 28°F hard freezes, Summit 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 Summit?
The federal record around Summit runs heavier than most — 1,059 documented sites, mostly Underground Storage Tanks entries (392), the nearest Underground Storage Tanks record about 0.5 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 Summit?
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 Summit's scale — its 9b band and its 313-day season. Your yard writes its own version of Summit'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 Summit’s own scale
5 of the readings below were taken at Summit's own scale — the 2,342 acres it covers and 1,059 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Summit's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 1,059 documented contamination sites on the federal record near Summit, the closest Underground Storage Tanks record about 0.5 miles out from the town centreFederal environmental registers
- Summit's boundary and the 2,342 acres inside itUS Census TIGER/Line 2025
- The ecoregion at Summit's own centroid, the Sonoran Basin and RangeUS EPA Level III Ecoregions
- Lanternfly survey cells around Summit checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Summit 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 Summit's 2,342 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 Summit's 2,342 acreswhy one lot differs from the next →
- Which side of Summit you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,342 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 Summit-wide figureread your own land →