Armstrong County, in Texas, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The conditions favor cabbage, hazelnut, california poppy, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Armstrong County lies within the Texas High Plains / Panhandle and the High Plains — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Armstrong County holds more than one microclimate.
Soils and elevations shift across Armstrong County, so your frost dates and drainage aren't the county average. 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 Armstrong County — soil, climate, flood, and parcel records. How we handle your address.
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Armstrong County — the short answer
Armstrong County, Texas: USDA zone 7a, about 216 days between hard freezes, across 582K acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 2
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 4
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~216
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 582K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 Armstrong County's average, not your lot's — a low corner or a tree line moves it. Against Armstrong County's 216-day season, see what your own ground reads.
Heat and winter chill in Armstrong County
Across a year, Armstrong County accumulates about 4,082 growing degree days above 50°F, about 1,742 fewer than the middle Texas county — ahead of 14 of Texas’s 254 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Winter banks about 2,280 hours below 45°F, 1,185 more than the Texas middle of 1,095. Chill is what tells a fruit tree its dormancy is over, and it is set by climate rather than by anything you can build.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Armstrong County
Across Armstrong County, the ground is predominantly Mollisols, where Pullman, Mobeetie, and Quinlan are the most extensive named soil series. The soil is generally well drained with a silty clay loam surface. Topsoil pH runs about 7.5–8.0, slightly alkaline. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
46%
Hydric soils
3%
Soil still varies lot by lot — soil types explained.
How the ground varies across Armstrong County
The USDA soil survey maps 93% of Armstrong County as well drained — but another 7% drains differently: 3% moderately well drained, 3% poorly drained.
Pullman is the most extensive named soil at 38% of mapped acres, then Mobeetie (8%) and Quinlan (6%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Armstrong County
Each reading below is measured for Armstrong County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Armstrong County are well drained, in hydrologic group C — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Armstrong County runs about pH 7.5–8.0, on the alkaline side.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Season length
MeasuredArmstrong County runs about 216 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
MeasuredArmstrong County 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 Armstrong County is in
Armstrong County spans 2 EPA Level III ecoregions — Southwestern Tablelands (52%) and High Plains (48%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Armstrong County
We scored all 1,086 plants against Armstrong County's own USDA zone 7a and its own 216-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Texas profile.
Is it too late to plant in Armstrong County?
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 Mar 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 2 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 4 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
What gets applied to farmland in Armstrong County
USGS estimates 42,135 lb of Glyphosate on Armstrong County farmland in 2019, its largest by weight, ahead of Atrazine (30,008 lb) and 2,4-d (28,740 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Armstrong County — and how to grow with it.
We checked the federal record across Armstrong County — 22 documented sites across 3 of the 9 source types we track.
The most significant on record: 1 brownfield site. Former commercial or industrial land where legacy contamination may persist.
The federal record across Armstrong County is light. Growing food here starts from a strong position — a quick pass over the map tells you whether any recorded site sits near your land, and if one does, that's information to plant with, not a reason to stop.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Armstrong County
Closest first, across Armstrong County. Listing isn't leaking, and distance isn't exposure.
- BARRERA CAFEUnderground Storage Tanks · 400 ft
- TXDOTUnderground Storage Tanks · 400 ft
- BUTLERS SHAMROCKUnderground Storage Tanks · 400 ft
- SORELLE FARMUnderground Storage Tanks · 400 ft
- THOMPSON GARAGEUnderground Storage Tanks · 400 ft
- PHILLIPS 66 001230Underground Storage Tanks · 400 ft
- GILVIN TERRILLUnderground Storage Tanks · 400 ft
- H B JORDAN & COUnderground Storage Tanks · 400 ft
- DOBE FUELUnderground Storage Tanks · 400 ft
- WAYSIDE RADIO RELAY TOWERUnderground Storage Tanks · 400 ft
- PALO DUROUnderground Storage Tanks · 400 ft
- BALLARD TEXACOUnderground Storage Tanks · 400 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Armstrong County'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 Armstrong County.
Severity Distribution
across Armstrong County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Check your specific parcel in Armstrong County
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 Armstrong County average
Your land is one point inside Armstrong County
Everything above resolves to Armstrong County as a whole — one PHZM band and one county frost record, read across 582K 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 county 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 county average.
Your Lot vs the Armstrong County Average
Armstrong County Average
- ●USDA Zones 7a, averaged across Armstrong County
- ●One soil character for all of Armstrong County
- ●Frost dates read at Armstrong County's scale: Apr 2 to Nov 4
YOUR Parcel
- ✓Your exact zone, not Armstrong County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Armstrong County
Pull a site-specific report for your exact address in Armstrong County, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Armstrong County averages can't show:
We read public map data around Armstrong County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Armstrong County average
How we know this about Armstrong County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Armstrong County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Armstrong County
When does frost risk typically end in Armstrong County?
The last hard freeze (28°F) in Armstrong County typically lands around Apr 2, 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 23.
How long is the growing season in Armstrong County?
Measured between 28°F hard freezes, Armstrong County sees about 216 frost-free days — roughly Apr 2 through Nov 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 23 to Oct 21, about 181 days.
Is the soil safe to grow vegetables in Armstrong County?
The federal record around Armstrong County is light — 22 documented sites across the 9 federal source types we checked, mostly Underground Storage Tanks entries (19), 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.
Everything above is measured at Armstrong County's scale — its 7a band and its 216-day season. Your yard writes its own version of Armstrong County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Texas's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Armstrong County’s own scale
8 of the readings below were taken at Armstrong County's own scale — its own ~216-day span between 28°F freezes, the 3 most extensive soil series mapped here and 22 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Armstrong County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Armstrong County's own 28°F hard-freeze dates and its ~216-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Armstrong CountyUSDA NRCS SSURGO
- 22 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record under a tenth of a mile outFederal environmental registers
- Armstrong County's boundary and the 581,839 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~216-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Armstrong County spans, Southwestern Tablelands the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Armstrong County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Texas grower plans around — written at state scale, so they stay on the state guidefrom Texas
What this page can’t tell you
- How the season shifts across Armstrong County — the ~216 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Armstrong County's 581,839 acreswhy one lot differs from the next →
- Which of those 22 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Armstrong Countyread your own land →