Honolulu County, in Hawaii, sits in USDA hardiness zones 10a-11b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Crops well matched to these conditions include artichoke, meyer lemon, california poppy, and cabbage — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring
Honolulu County holds more than one microclimate.
Soils and elevations shift across Honolulu 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 Honolulu County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Honolulu County — the short answer
Honolulu County, Hawaii: USDA zones 10a-11b, no 28°F killing freeze on record — the season is year-round, across 385K acres.
- USDA zones
- 10a-11b
- USDA PHZM 2023
- Killing freeze
- None on record
- EWA KALAELOA AP station, 10 ft — 22 km away, 27 yr record
- County area
- 385K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. The year-round finding is measured — a 30-year record with no 28°F killing freeze in it — never inferred from missing dates.
Hardiness Zone Range
Zone 10a-11b is Honolulu County's average, not your lot's — a low corner or a tree line moves it. Against Honolulu County's no killing freeze on record, see what your own ground reads.
Soil in Honolulu County
Across Honolulu County, the ground is predominantly Entisols, where Helemano, Wahiawa, and Waikane are the most extensive named soil series. The soil is generally well drained with a silty clay surface. Topsoil pH runs about 4.8–6.7, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Entisols
Drainage
Well drained
Prime farmland
1%
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Honolulu County
The USDA soil survey maps 85% of Honolulu County as well drained — but another 10% drains differently: 5% excessively drained, 3% poorly drained.
Helemano is the most extensive named soil at 8% of mapped acres, then Wahiawa (7%) and Waikane (3%).
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 Honolulu County
Each reading below is measured for Honolulu 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 Honolulu County are well drained, in hydrologic group B — 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 Honolulu County runs about pH 4.8–6.7, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredHonolulu County records no 28°F killing freeze at all across the 30-year station record — year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredHonolulu County sits in USDA hardiness zones 10a-11b.
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
What Grows in Honolulu County
We scored all 1,086 plants against Honolulu County's own USDA zone 10a-11b and its own 365-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 Hawaii profile.
Documented around Honolulu County
- monarch butterfly77 documented records
Sighting records, so they follow observers as much as insects.
Safe to Grow Here?
What the federal record shows across Honolulu County — and how to grow with it.
We checked the federal record across Honolulu County — 2,810 documented sites across 7 of the 9 source types we track.
The most significant on record: 67 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Honolulu 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.
What's on the federal record near Honolulu County
Closest first, across Honolulu County. Listing isn't leaking, and distance isn't exposure.
- Makaha 76/7-Eleven (#161)Underground Storage Tanks · 1500 ft
- MAKAHA CENTRAL OFFICEUnderground Storage Tanks · 1900 ft
- ANGEL'S MAKAHA UNION 5245Underground Storage Tanks · 2300 ft
- PU'UWAI 'O MAKAHABrownfields · 0.6 mi
- LEEWARD PETROLEUM SERVICE STATIONBrownfields · 0.7 mi
- HILYFE VAPORZ, LLCBrownfields · 0.7 mi
- SHERATON MAKAHA RESORT GOLF CSBrownfields · 0.8 mi
- MAKAHA VALLEY COUNTRY CLUBUnderground Storage Tanks · 1.0 mi
- C&CH WAIANAE FIRE STATIONUnderground Storage Tanks · 1.0 mi
- WAIANAE CENTRAL OFFICEUnderground Storage Tanks · 1.1 mi
- MAKUA MILITARY RESERVATION ORDN DISPSuperfund · 1.2 mi
- LEEWARD PETROLEUM COMPANY - Bulk PlantUnderground Storage Tanks · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Honolulu 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 Honolulu County.
Sources Checked
across Honolulu County
Severity Distribution
across Honolulu County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Honolulu County, Superfund runs higher than the national average — 67 sites across Honolulu County. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Honolulu 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 Honolulu County average
Your land is one point inside Honolulu County
Everything above resolves to Honolulu County as a whole — one PHZM band and one county frost record, read across 385K 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 Honolulu County Average
Honolulu County Average
- ●USDA Zones 10a-11b, averaged across Honolulu County
- ●One soil character for all of Honolulu County
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Honolulu County's 10a-11b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Honolulu County
Pull a site-specific report for your exact address in Honolulu County, Hawaii — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Honolulu County averages can't show:
We read public map data around Honolulu County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Honolulu County average
How we know this about Honolulu 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 Honolulu County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Honolulu County
Is it too late to plant in Honolulu County?
No — Honolulu County has no 28°F killing freeze in the 30-year station record, so the growing season is year-round and there is no last-frost date to wait for. Planting is paced by rainfall, heat and daylength instead of by frost: start heat-lovers any month, and time cool-season crops (lettuce, brassicas, peas) for the cooler, wetter half of the year or for higher ground. Succession sowing every few weeks works all year, so the limit is what you can keep watered and harvested, not the calendar.
When does frost risk typically end in Honolulu County?
It doesn't — Honolulu County records no 28°F killing freeze at all across the 1991–2020 station record, so there is no spring frost date to plant after. Cold still matters with elevation: the higher you garden, the cooler the nights, and a few tropical crops sulk below about 60°F even where they never freeze.
How long is the growing season in Honolulu County?
Year-round — the 1991–2020 station record for Honolulu County contains no 28°F killing freeze, so there is no season to measure between freezes. What paces planting instead is heat, rainfall and daylength: the hottest, wettest stretch is the hard part for cool-season crops, not winter. Elevation is the one real exception — the higher you garden, the colder the nights get.
Is the soil safe to grow vegetables in Honolulu County?
The federal record around Honolulu County runs heavier than most — 2,810 documented sites, mostly Underground Storage Tanks entries (1,572), the nearest Underground Storage Tanks record about 0.3 miles out — 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.
Everything above is measured at Honolulu County's scale — its 10a-11b band and its no killing freeze on record. Your yard writes its own version of Honolulu 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 Hawaii's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Honolulu County’s own scale
7 of the readings below were taken at Honolulu County's own scale — a 30-year record with no killing freeze in it, the 3 most extensive soil series mapped here and 2,810 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Honolulu County's own USDA hardiness band, zones 10a-11bUSDA PHZM 2023
- No 28°F killing freeze in Honolulu County's own 30-year station record — a year-round growing season, measured here rather than inheritedNOAA Regional Climate Centers ACIS, 1991-2020
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Honolulu CountyUSDA NRCS SSURGO
- 2,810 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.3 miles outFederal environmental registers
- Honolulu County's boundary and the 384,506 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 10a-11b and a ~365-day seasonGrowable Ground crop-matching engine
- Open occurrence records documented in Honolulu County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
Inherited from a wider read
- The growing challenges every Hawaii grower plans around — written at state scale, so they stay on the state guidefrom Hawaii
What this page can’t tell you
- How the season shifts across Honolulu County — the ~365 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 Honolulu County's 384,506 acreswhy one lot differs from the next →
- Which of those 2,810 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 Honolulu Countyread your own land →