Gardening in Urban Honolulu, HI
This metro spans USDA zones 12a to 13a, so there is no single zone for Urban Honolulu, HI and anyone who gives you one is rounding. 76% of its ZIP codes are zone 12b; the rest are not.
Which zone you are in depends where you are
Urban Honolulu, HI covers 3 hardiness zones. A guide that gives the metro one zone has picked whichever is largest and rounded everyone else into it — which is fine for the 76% in zone 12b and wrong for the other 24%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 12b | 28 | 76% | |
| 12a | 8 | 22% | |
| 13a | 1 | 3% |
Zones are published per ZIP code, so yours is exact even though the metro's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
No freeze range is shown for Urban Honolulu, HI, because at least one station here records no freeze at any probability, so there is no date to average. The tools below still answer for individual ZIP codes here, and will say what applies.
Your growing season
NOAA publishes a growing-season length for each station, and across the 13 stations serving Urban Honolulu, HI it runs 365 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 79–88 °F , below the 90 °F point where cool-season crops reliably bolt.
What survives the winter changes across Urban Honolulu, HI
Of 74 perennial fruits, nuts, berries, vegetables and herbs, 14 come through the winter in every zone this metro covers.
| Zone | ZIPs | Survive | Fail for being too warm |
|---|---|---|---|
| 12a | 8 | 14 of 74 | 60 |
| 12b | 28 | 14 of 74 | 60 |
| 13a | 1 | 14 of 74 | 60 |
The last column is the counterintuitive one, and it is why the totals do not simply rise as the winters get milder. Most temperate fruit needs a documented number of hours below about 45 °F to break dormancy and set a crop, so an apple fails in a winter that is too warm; currants and rhubarb cook in the summer heat that comes with it. See the full list with reasons.
The 13 stations behind these numbers
Every figure above comes from these, and each is named so you can check it. Distances vary by ZIP code, so the tools report yours rather than this page guessing.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Ewa Beach Usgs 702.2, HI | USC00511918 | no freeze recorded | no freeze recorded | 365 days |
| Honolulu INTL AP, HI | USW00022521 | no freeze recorded | no freeze recorded | 365 days |
| Kaneohe 838.1, HI | USC00513117 | no freeze recorded | no freeze recorded | 365 days |
| Kaneohe Bay Mcas, HI | USW00022519 | no freeze recorded | no freeze recorded | 365 days |
| Kapaka Farm 904.1, HI | USC00513208 | no freeze recorded | no freeze recorded | 365 days |
| Kii-Kahuku 911, HI | USC00514500 | no freeze recorded | no freeze recorded | 365 days |
| Makaha Ctry Club 800.3, HI | USC00515758 | no freeze recorded | no freeze recorded | 365 days |
| Manoa Lyon Arbo 785.2, HI | USC00516128 | no freeze recorded | no freeze recorded | 365 days |
| Puu Manawahua 725.6, HI | USC00518500 | no freeze recorded | no freeze recorded | 365 days |
| Upper Wahiawa 874.3, HI | USC00518838 | no freeze recorded | no freeze recorded | 365 days |
| Waihee 837.5, HI | USC00519281 | no freeze recorded | no freeze recorded | 365 days |
| Waikiki 717.2, HI | USC00519397 | no freeze recorded | no freeze recorded | 365 days |
| Waimanalo Exp F 795.1, HI | USC00519523 | no freeze recorded | no freeze recorded | 365 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Work out your own dates
Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.
- What survives my winter?
Runs on the hardiness zone, so it answers for all of Urban Honolulu, HI at once — zone across 74 perennial fruits, berries, vegetables and herbs.
- When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
- When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
- What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.
Where these numbers come from
The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates are NOAA's 1991–2020 Climate Normals, read from every station whose normals cover a ZIP code in this metro. Nothing here is estimated, and no station stands in for another.
This page names no single station on purpose. Picking one to represent a metro sounds reasonable and is not: the station serving the most ZIP codes is an artifact of where ZIP centroids happen to fall, and it selects a lock on the Monongahela for Pittsburgh and a far southern suburb for Chicago. A range across every station is true; a single cited date for a whole metro is not.