Hammon, Oklahoma, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Crops well matched to these conditions include cabbage, hazelnut, california poppy, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Hammon, 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 Hammon 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 Hammon — soil, climate, flood, and parcel records. How we handle your address.
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Hammon — the short answer
Hammon, Oklahoma: USDA zone 7a, about 226 days between hard freezes, across 468 acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~226
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 468 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 Hammon's average, not your lot's — a low corner or a tree line moves it. Against Hammon's 226-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Hammon
Each reading below is measured for Hammon itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHammon runs about 226 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredHammon 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 Hammon is in
Hammon sits in the Central Great Plains — EPA Level III, inside the wider Great Plains. That is read at Hammon's own centroid rather than borrowed from Roger Mills County.
What Grows in Hammon
Every plant below cleared Hammon's own zone 7a and its 226-day season. Each card opens that plant's Oklahoma profile. How we score.
Is it too late to plant in Hammon?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Feb 26; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 26 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 7 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
What's on the federal record near Hammon
Closest first, within ~10 miles of Hammon. Listing isn't leaking, and distance isn't exposure.
- Hammon Cooperative AssociationUnderground Storage Tanks · 400 ft
- Bakers Oil CoUnderground Storage Tanks · 500 ft
- Hammon Public SchoolUnderground Storage Tanks · 1400 ft
- Roger Mills County Dist #2Underground Storage Tanks · 0.5 mi
- J.C.'s HammonUnderground Storage Tanks · 0.5 mi
- J.C.'s Hammon #2Underground Storage Tanks · 0.5 mi
- H & C Equipment CoUnderground Storage Tanks · 0.6 mi
- Delmer HigginsUnderground Storage Tanks · 0.7 mi
- 14N-20W-16 CCD 1Nitrate · 4.3 mi
- Orvil Morton-Herbert MortonUnderground Storage Tanks · 4.6 mi
- 14N-20W-36 BAB 1Nitrate · 5.9 mi
- Washita Nwr, Us Fish & WildlifeUnderground Storage Tanks · 6.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Hammon'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 Hammon.
Total Sites
29
within ~10 miles of Hammon
Risk Level
Low
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Hammon
Severity Distribution
within ~10 miles of Hammon
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hammon, Nitrate runs higher than the national average — 14 sites within ~10 miles of Hammon. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Hammon
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 Hammon average
Your land is one point inside Hammon
Everything above resolves to Hammon as a whole — one PHZM band and one 28°F frost record, read across 468 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 Hammon Average
Hammon Average
- ●USDA Zones 7a, averaged across Hammon
- ●One soil character for all of Hammon
- ●Frost dates read at Hammon's scale: Mar 26 to Nov 7
YOUR Parcel
- ✓Your exact zone, not Hammon's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Hammon
Pull a site-specific report for your exact address in Hammon, Oklahoma — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hammon averages can't show:
We read public map data around Hammon — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hammon average
How we know this about Hammon
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 Hammon’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 Hammon
When does frost risk typically end in Hammon?
The last hard freeze (28°F) in Hammon typically lands around Mar 26, 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 Apr 16.
When is the first frost in Hammon?
The first hard freeze (28°F) in Hammon typically arrives around Nov 7, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 24, so the watching starts about Oct 8 — about 226 days after the spring freeze cleared.
How long is the growing season in Hammon?
Measured between 28°F hard freezes, Hammon sees about 226 frost-free days — roughly Mar 26 through Nov 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 16 to Oct 24, about 191 days.
Is the soil safe to grow vegetables in Hammon?
The federal record around Hammon is light — 29 documented sites across the 9 federal source types we checked, mostly Nitrate entries (14), the nearest Underground Storage Tanks record under a tenth of a mile out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do I protect my plants from frost in Hammon?
From about Oct 8 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 7 (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 7. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Hammon's scale — its 7a band and its 226-day season. Your yard writes its own version of Hammon'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 Hammon’s own scale
6 of the readings below were taken at Hammon's own scale — its own ~226-day season between 28°F freezes, the 468 acres it covers and 29 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Hammon's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Hammon's own 28°F hard-freeze dates, about Mar 26 and Nov 7 and the ~226-day span between themNOAA 1991–2020 Climate Normals
- 29 documented contamination sites on the federal record near Hammon, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Hammon's boundary and the 468 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~226-day seasonGrowable Ground crop-matching engine
- The ecoregion at Hammon's own centroid, the Central Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Hammon's 468 acres read through its county's SSURGO summaryfrom Roger Mills County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Roger Mills County
- The growing challenges every Oklahoma grower plans around — written at state scale, so they stay on the state guidefrom Oklahoma
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Roger Mills County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Hammon's 468 acreswhy one lot differs from the next →
- Which side of Hammon you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 468 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Hammon-wide figureread your own land →
More in Oklahoma
Wider growing context
What grows across OklahomaHammon sits outside our named growing regions, so Oklahoma as a whole is its closest context here.
Nearby growing guides