The Lower Colorado River Corridor spans USDA hardiness zones 9a-10a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
The river towns from Bullhead City to Parker — essentially frost-free 9a-10a bottomland where citrus and winter gardens run while the Mohave high desert a half-hour up the grade freezes. On paper, palo verde, jalapeno, date palm, and citrus all suit these conditions — on the ground, soil, sun, and drainage make the final call.
The Lower Colorado River Corridor spans Arizona.
Your yard isn't all of the Lower Colorado River Corridor.
The Lower Colorado River Corridor spans USDA zones 9a-10a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Lower Colorado River Corridor — soil, climate, flood, and parcel records. How we handle your address.
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The Lower Colorado River Corridor — the short answer
The Lower Colorado River Corridor: USDA zones 9a-10a, in Arizona.
- USDA zones
- 9a-10a
- USDA PHZM 2023, aggregated over the footprint
- Towns
- 5
- US Census TIGER/Line 2025
- Region type
- Town cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in the Lower Colorado River Corridor
Plants matched to the Lower Colorado River Corridor's USDA zones 9a-10a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Lower Colorado River Corridor
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Lower Colorado River Corridor’s USDA zones 9a-10a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground around the Lower Colorado River Corridor
The USDA soil survey maps this ground county by county. These are those records weighted by land area across the two counties containing the Lower Colorado River Corridor — the ground the Lower Colorado River Corridor sits in, read at the only grain the survey publishes.
In the counties containing the Lower Colorado River Corridor, the ground is predominantly Aridisols, at 60% of mapped acres, followed by Entisols (33%), Mollisols (4%) and Alfisols (2%). Six soil orders appear in that record, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Gunsight, Mellenthin, and Hyder.
56% of those acres are well drained, and another 29% somewhat excessively drained, 6% excessively drained. Topsoil pH runs 7.8–8.2 between the lowest and the highest county on record.
Soil order
Aridisols
Drainage
Well drained
Topsoil pH
7.8–8.2
Hydric soils
0%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Lower Colorado River Corridor
The soil survey reads this ground county by county, and the readings above are the record for the counties containing the Lower Colorado River Corridor. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records56% of the mapped acres across the counties containing the Lower Colorado River Corridor are well drained — ground that drains quickly. The survey maps this ground county-wide, so it describes the setting the Lower Colorado River Corridor sits in rather than the valley floor alone.
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
From county recordsTopsoil across the counties containing the Lower Colorado River Corridor runs pH 7.8–8.2 — alkaline in all two of them.
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
Safe to Grow Here?
What the federal record shows across the Lower Colorado River Corridor — and how to grow with it.
Across the 2 counties containing the Lower Colorado River Corridor the federal record holds 2,488 documented sites, mostly Mining (976), Nitrate (764) and Underground Storage Tanks (532). The heaviest single county is Mohave County, with 1,592.
That is the containing counties' count — this region is a smaller piece of that ground, so it is context, not a reading of any one lot. Open the map outlined to the Lower Colorado River Corridor to see which records sit where you actually grow.
Sources Checked
Summed across the 2 counties containing the Lower Colorado River Corridor
A note from Gnorman
What an experienced grower watches for around here
In and around the Lower Colorado River Corridor, two things run higher than the national average across the 2 counties containing the Lower Colorado River Corridor — Mining (976 sites) and Nitrate (764 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Lower Colorado River Corridor
Everything above resolves to the Lower Colorado River Corridor as a whole — a footprint spanning USDA zones 9a-10a. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs the Lower Colorado River Corridor Average
Lower Colorado River Corridor Average
- ●USDA Zones 9a-10a, averaged across Lower Colorado River Corridor
- ●One soil character for all of Lower Colorado River Corridor
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Lower Colorado River Corridor's 9a-10a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Lower Colorado River Corridor
Pull a site-specific report for your exact address in the Lower Colorado River Corridor — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Lower Colorado River Corridor averages can't show:
We read public map data around The Lower Colorado River Corridor — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Lower Colorado River Corridor average
How we know this about the Lower Colorado River Corridor
The boundary: the region's own towns — a footprint finer than any county, because the county average would misread this microclimate. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the towns inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Lower Colorado River Corridor
What hardiness zone is the Lower Colorado River Corridor?
The Lower Colorado River Corridor spans USDA hardiness zones 9a-10a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's own towns. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
What grows well in the Lower Colorado River Corridor?
The Lower Colorado River Corridor's conditions suit plants such as Palo Verde, Jalapeno, Date Palm, Citrus, Prickly Pear. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Lower Colorado River Corridor defined?
The Lower Colorado River Corridor is a true microclimate — smaller than the counties that contain it, with a growing reality of its own. So this page is built from the region's own 5 towns, each carrying its own hardiness zone and frost record, rather than from a county average measured somewhere else.
Which states does the Lower Colorado River Corridor cover?
The Lower Colorado River Corridor spans Arizona. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Sonoran Desert, Sonoita / Elgin, White Mountains (Eastern Arizona), Willcox AVA, Flagstaff & San Francisco Peaks High Country, and Mogollon Rim Country (Payson) share at least one state with the Lower Colorado River Corridor. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Lower Colorado River Corridor’s own scale
5 of the readings below were taken at the Lower Colorado River Corridor's own scale — the zone 9a-10a band across its footprint and 2,488 documented federal contamination records across its 2 counties, 1,592 of them in Mohave County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 9a-10a aggregated across all 5 towns in the footprintUSDA PHZM 2023
- The boundary itself — the 5 towns this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The federal contamination record over the whole footprint — 2,488 documented federal contamination records across its 2 counties, 1,592 of them in Mohave County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 60% Aridisols, topsoil pH 7.8–8.2, area-weighted across its 2 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 9a-10afrom Arizona
What this page can’t tell you
- Frost dates — they swing too far across a footprint this size to quote as one regional numberfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Lower Colorado River Corridor
State growing guides
Towns in this region
Counties containing this region
Other growing regions across Arizona
A warm desert of saguaro and palo verde with mild winters that allow desert citrus, dates, and prickly pear alongside intensive irrigated gardening.
Defined by the TTB's Sonoita American Viticultural Area (27 CFR § 9.97) — Arizona's first AVA, established in 1984 — this high-desert grassland spans Cochise, Pima, and Santa Cruz counties across USDA zones 8a to 9a, where the frost-free season runs roughly 264 to 313 days.
Arizona's high green country — at the White Mountain towns the committed record reads 6a-7a with a 145-176-day season, mountain gardening closer to Colorado than to the desert two hours down the hill.
Established by the TTB in 2016 across parts of Cochise and Graham Counties in southeastern Arizona, the Willcox AVA spans USDA hardiness zones 8a to 8b with a roughly 264-to-266-day frost-free season.
The cold antithesis of desert Arizona: a ponderosa-pine plateau near 7,000 ft where Flagstaff sits in USDA zone 6a and Bellemont drops to 5b, with only about 150 frost-free days — roughly mid-May last frost to mid-October first frost (Coconino County, api/data/county_data.json). The statewide "zone 9b, near-frost-free" framing is actively wrong here; growers plan around snow, a short cool-season window, and hard frost dates instead of citrus and dates.
Payson's mid-elevation shelf under the Mogollon Rim — real winter frost and a 7b-8a, 214-237-day season that splits the difference between the low desert's heat and the Rim top's snow; pine-country gardening with monsoon summers.