Kauai County, in Hawaii, sits in USDA hardiness zones 10a-11b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
On paper, taro, mango, macadamia, and coffee all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring
Kauai County holds more than one microclimate.
Soils and elevations shift across Kauai County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Quick Facts
USDA Zones
10a-11b
Last Frost (state avg.)
None
First Frost (state avg.)
None
County Area
397K acres
Hardiness Zone Range
Growing Season
Zone maps are averages across Kauai County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Kauai County
Across Kauai County, the ground is predominantly Oxisols, where Lihue, Puhi, and Makaweli are the most extensive named soil series. The soil is generally well drained with a silty clay loam surface. Topsoil pH runs about 4.3–5.8, very strongly acidic. Rainfall drains through hydrologic group C soils.
Soil order
Oxisols
Drainage
Well drained
Prime farmland
10%
Hydric soils
4%
Soil still varies lot by lot — soil types explained.
What Grows in Kauai County
Plants matched to Kauai County's USDA zones 10a-11b — each links to its full growing profile.
Growing Challenges in Hawaii
What an experienced grower plans around here — each one has a move.
Extreme rainfall variation — desert on one side, rainforest on the other
Your side of the island decides everything — check your exact spot's rainfall before choosing crops.
Volcanic soil is nutrient-poor in young flows
A soil test shows what young lava ground is missing — compost and targeted amendments close the gap fast.
Invasive species pressure is severe
Source clean plant material and learn the current watch list — your extension office is the authority on what to keep out.
For cultivar selection, pest pressure, and planting-time guidance specific to Hawaii, the UH Mānoa CTAHR Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Kauai County — and how to grow with it.
We checked the federal record across Kauai County — 377 documented sites across 6 of the 9 source types we track.
The most significant on record: 7 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Kauai County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across Kauai County
Severity Distribution
across Kauai County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Kauai County, two things run higher than the national average — PFAS (6 sites) and Superfund (7 sites). That's not a problem with your land — it's information about it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Kauai County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Kauai County Average
- ●USDA Zones 10a-11b
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Kauai County
Pull a site-specific report for your exact address in Kauai County, Hawaii — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Kauai County, Hawaii
- USDA Hardiness Zones: 10a-11b (USDA PHZM 2023)
- Last Spring Frost (state avg.): None (NOAA 30-Year Climate Normals)
- First Fall Frost (state avg.): None (NOAA 30-Year Climate Normals)
- County Land Area: 397K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Kauai County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Kauai County, Hawaii?
Kauai County sits in USDA hardiness zones 10a-11b, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
When does frost risk typically end in Kauai County?
Kauai County follows Hawaii's statewide frost window: last spring frost around None and first fall frost around None, per NOAA 30-year climate normals (1991–2020). Frost dates shift with elevation and local microclimate, so watch your own site's cold pockets.
What vegetables grow in Kauai County?
Kauai County's zones 10a-11b support a wide range — strong performers include Taro, Mango, Macadamia, Coffee, and Plumeria. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Kauai County, really?
Officially, Kauai County sits in USDA zones 10a-11b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Kauai County?
The federal record around Kauai County runs heavier than most — 377 documented sites — 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.
Just moved to Kauai County — what should I know before planting?
Start with three facts. Kauai County sits in USDA zones 10a-11b, which sets what survives winter; the statewide frost window runs about None to None (NOAA 30-year climate normals); and 377 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Kauai County average. Your yard writes its own version — 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 Hawaii's frost window, season length, and soil profile against the plant's real requirements.