St. Johns, Arizona, sits in USDA hardiness zone 7a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Among the crops suited to this profile: cabbage, pawpaw, california poppy, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in St. Johns, 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 St. Johns 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 St. Johns — soil, climate, flood, and parcel records. How we handle your address.
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St. Johns — the short answer
St. Johns, Arizona: USDA zone 7a, about 196 days between hard freezes, across 17K acres of city.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 14
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~196
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 17K 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 7a is St. Johns's average, not your lot's — a low corner or a tree line moves it. Against St. Johns's 196-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in St. Johns
Each reading below is measured for St. Johns itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSt. Johns runs about 196 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSt. Johns sits in USDA hardiness zone 7a.
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 St. Johns is in
St. Johns sits in the Arizona/New Mexico Plateau — EPA Level III, inside the wider North American Deserts. That is read at St. Johns's own centroid rather than borrowed from Apache County.
What Grows in St. Johns
Every plant below cleared St. Johns's own zone 7a and its 196-day season. Each card opens that plant's Arizona profile. How we score.
Is it too late to plant in St. Johns?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 17; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 14 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 27 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near St. Johns
Closest first, within ~10 miles of St. Johns. Listing isn't leaking, and distance isn't exposure.
- SAINT JOHNS MAVERICK STORE 131Underground Storage Tanks · 2300 ft
- WAITE'S UNION 76Underground Storage Tanks · 2400 ft
- AMERIGAS PROPANE - ST. JOHNSUnderground Storage Tanks · 0.5 mi
- DAVIS PROPERTYUnderground Storage Tanks · 0.5 mi
- HAMMOND PROPERTYUnderground Storage Tanks · 0.5 mi
- A-13-28 28DADNitrate · 0.6 mi
- BRIDES AUTO CENTERUnderground Storage Tanks · 0.6 mi
- APACHE COUNTY - ROAD DEPARTMENTUnderground Storage Tanks · 0.7 mi
- ADOT - ST JOHNS MAINTENANCEUnderground Storage Tanks · 0.7 mi
- A-13-28 29AADNitrate · 0.8 mi
- CIRCLE K #663Underground Storage Tanks · 0.8 mi
- TTMW-8Nitrate · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from St. Johns'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 St. Johns.
Total Sites
125
within ~10 miles of St. Johns
Risk Level
Moderate
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of St. Johns
Severity Distribution
within ~10 miles of St. Johns
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around St. Johns, Nitrate runs higher than the national average — 106 sites within ~10 miles of St. Johns. 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 St. Johns
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 St. Johns average
Your land is one point inside St. Johns
Everything above resolves to St. Johns as a whole — one PHZM band and one 28°F frost record, read across 17K 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 city 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 St. Johns Average
St. Johns Average
- ●USDA Zones 7a, averaged across St. Johns
- ●One soil character for all of St. Johns
- ●Frost dates read at St. Johns's scale: Apr 14 to Oct 27
YOUR Parcel
- ✓Your exact zone, not St. Johns's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in St. Johns
Pull a site-specific report for your exact address in St. Johns, Arizona — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that St. Johns averages can't show:
We read public map data around St. Johns — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the St. Johns average
How we know this about St. Johns
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at St. Johns’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 city grain anywhere on this page — there is no city-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 St. Johns
When does frost risk typically end in St. Johns?
The last hard freeze (28°F) in St. Johns typically lands around Apr 14, 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 May 5.
When is the first frost in St. Johns?
The first hard freeze (28°F) in St. Johns typically arrives around Oct 27, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 13, so the watching starts about Sep 27 — about 196 days after the spring freeze cleared.
How long is the growing season in St. Johns?
Measured between 28°F hard freezes, St. Johns sees about 196 frost-free days — roughly Apr 14 through Oct 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 5 to Oct 13, about 161 days.
Is the soil safe to grow vegetables in St. Johns?
The federal record around St. Johns shows 125 documented sites, mostly Nitrate entries (106), the nearest Underground Storage Tanks record about 0.4 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in St. Johns?
From about Sep 27 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 Oct 27 (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 Oct 27. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at St. Johns's scale — its 7a band and its 196-day season. Your yard writes its own version of St. Johns'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 St. Johns’s own scale
6 of the readings below were taken at St. Johns's own scale — its own ~196-day season between 28°F freezes, the 16,581 acres it covers and 125 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- St. Johns's own USDA hardiness band, zones 7aUSDA PHZM 2023
- St. Johns's own 28°F hard-freeze dates, about Apr 14 and Oct 27 and the ~196-day span between themNOAA 1991–2020 Climate Normals
- 125 documented contamination sites on the federal record near St. Johns, the closest Underground Storage Tanks record about 0.4 miles out from the town centreFederal environmental registers
- St. Johns's boundary and the 16,581 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~196-day seasonGrowable Ground crop-matching engine
- The ecoregion at St. Johns's own centroid, the Arizona/New Mexico PlateauUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so St. Johns's 16,581 acres read through its county's SSURGO summaryfrom Apache County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Apache 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 Apache County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among St. Johns's 16,581 acreswhy one lot differs from the next →
- Which side of St. Johns you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 16,581 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.4 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 St. Johns-wide figureread your own land →
More in Arizona
Wider growing context
What grows across ArizonaSt. Johns sits outside our named growing regions, so Arizona as a whole is its closest context here.
Nearby growing guides