What CTAHR Cooperative Extension Does in Hawaii
The Cooperative Extension Service at the University of Hawaii College of Tropical Agriculture and Human Resources (CTAHR) is the state's land-grant outreach arm. Per the college's Extension overview, it provides science-based information and educational programs in agriculture, natural resources and human resources, and it is a partnership among federal, state and local governments. Each Hawaii county has a CTAHR administrator who oversees the college's resources and activities there, and more than 65 extension agents, specialists and program staff do the field work.
For a farmer, rancher, gardener or 4-H parent, the practical meaning is simple: there is a university-trained person on your island whose job is to answer questions about growing things, raising animals and running a household, usually at no charge. Fees, where they exist, are small and tied to workshops or organized activities.
What You Can Get From Your County Office
The overview page lists these services:
- Individual consultations with extension agents and program staff.
- Educational workshops and short courses on agriculture, home economics, family living, 4-H and other youth activities, nutrition and health.
- Free publications, brochures and videos at county offices. Workshops and organized activities may carry a small fee.
- The Agricultural Diagnostic Service Center, which offers insect identification, nematode counts, disease diagnosis, and soil, plant, water and feed analysis. It also sells vegetable and papaya seeds developed by the college.
Ask the office what to bring before you drive over. A pest or disease question goes faster with a fresh sample and a few clear photos, and a soil or water question goes faster if you know what crop you plan to grow.
Extension Offices by Island
A published list of Hawaii extension offices gives these locations. Phone numbers and addresses change, so confirm before you go.
Hawaii County (Big Island)
- Hilo, Komohana Research and Extension Center, 875 Komohana Street, (808) 969-8201
- Kamuela, 67-5189 Kamamalu Road, (808) 887-6183
- Kona, 79-7381 Mamalahoa Highway, Kealakekua, (808) 322-4892
Maui County
- Kahului, 310 Kaahumanu Ave., Bldg. 214, (808) 244-3242 x222
- Kula Station, 424 Mauna Place, (808) 878-1213
- Molokai, 526 Huaai Rd, Hoolehua, (808) 567-6929
Oahu (City and County of Honolulu)
- Honolulu, 1955 East-West Rd., Ag Sci III Room 217, (808) 956-7290
- Pearl City Urban Garden Center, 955 Kamehameha Highway, (808) 453-6050
- Wahiawa, 910 California Ave., (808) 622-4185
Kauai County
- Lihue, State Office Building, 3060 Eiwa Street, Room 210, (808) 274-3471
Master Gardener Program Example: Kauai
CTAHR also runs Master Gardener volunteer training. The Kauai Master Gardener page describes how it works on that island, and other islands may run things differently, so ask your own office.
- Applications for the 2025 class were taken through an online form. Reviews usually start around November and interviews are typically held in January, so apply before the end of the year.
- Training runs about 16 weeks, typically February to May, with about 64 hours of instruction taught by UH faculty and local experts. Topics include botany, plant propagation, organic gardening, native Hawaiian plants, pest management, plant diseases and soils.
- Classes meet at the Kauai Agricultural Research Center in Wailua Homesteads or over Zoom with hands-on activities. The course fee covers materials and is set yearly; the previous year's fee was $200.
- Graduates complete at least 50 volunteer hours in the first year to become certified. To stay active, members need at least 40 volunteer hours and 10 hours of continuing education each year.
- A "plant doctor" booth at the Puhi Grove Farm Farmers Market offers plant advice each Saturday from 9:30 a.m. to noon, and visitors can buy seeds from the University's Seed Lab.
The Kauai program coordinator can be reached at the Kauai extension office, (808) 274-3475.
4-H and Youth Programs
The Extension overview names 4-H and other youth activities among the workshops and programs it offers. It does not publish club rules there, so for membership, project requirements and livestock ownership dates, call your county office. Hawaii's 4-H livestock families also show up at events such as the Hawaii State Farm Fair; see the county fairs guide for details.
How CTAHR Shows Up Elsewhere
CTAHR people turn up outside the office too. When the Oahu District FFA career development competition was held on December 14, 2024 at Kahala Elementary School, four CTAHR faculty members judged contests. If your chapter or club wants a judge, speaker or demonstration, ask your county office whether someone is available.
Practical Tips
- Call the office nearest you first. The statewide overview says faculty and staff work from county offices and CTAHR Research and Extension Stations.
- Bring a sample, photos and notes on what you have already tried.
- Ask about the next workshop in your area and whether there is a fee.
- Pick up the free publications; they are written for Hawaii growing conditions.
- If you want to volunteer, ask about Master Gardener timelines early, since applications close months before classes start.
Frequently Asked Questions
Is Extension help free?
Consultations and publications at county offices are described as free, while workshops and organized activities may have a small fee.
Can Extension identify an insect or diagnose a plant disease?
Yes. The Agricultural Diagnostic Service Center handles insect identification, nematode counts and disease diagnosis, along with soil, plant, water and feed analysis.
Is there an office on every island?
The published office list shows locations on Hawaii Island, Maui, Molokai, Oahu and Kauai. Lanai is not on that list, so ask the Maui County office how it is served.
How do I become a Master Gardener?
Apply to your county program. On Kauai, applications are reviewed starting around November and training runs February to May.
Hawaii Listings Covered by This Guide
- Molokai 4-H Livestock County Show
Molokai 4-H youth exhibit market livestock at Lanikeha Community Center in Hoolehua as part of the Hawaii 4-H summer show season. Held each year; the most recent date was June 6, 2026.
2200 Farrington Ave., Hoolehua, HI | Organizer: Hawaii 4-H, CTAHR Official event details - Big Island 4-H Livestock County Show
Hawaii Island 4-H youth show steers, sheep, goats, pigs, rabbits and poultry at the Brian Anderson Arena in Honokaa before the state show. Held each year; the most recent date was June 20, 2026.
Honokaa, HI | Organizer: University of Hawaii CTAHR / Hawaii 4-H Official event details - Hawaii 4-H Livestock State Show
Statewide 4-H show on Oahu for steers, heifers, sheep, goats, pigs, rabbits and poultry, with a livestock auction at 5:30 p.m. on the first day. Held each year; the most recent dates were July 11-12, 2026.
Wahiawa, HI | Organizer: University of Hawaii CTAHR / Hawaii 4-H Official event details - Hawaii 4-H Livestock State Show and Sale
Two-day state finals for 4-H market livestock with a Saturday evening livestock auction, held at Whitmore Village in Wahiawa. Held each year; the most recent dates were July 11-12, 2026.
- Hawaii 4-H Horse Club State Show
Hawaii 4-H horse club members compete at Kualoa Ranch in Kaneohe, closing the summer 4-H livestock show season. Held each year; the most recent date was August 22, 2026.
Kaneohe, HI | Organizer: University of Hawaii CTAHR / Hawaii 4-H Official event details - CTAHR Cooperative Extension - Honolulu Extension Office
Oahu extension office on the Manoa campus handling Honolulu County horticulture and 4-H questions.
1955 East-West Rd., Ag Sci III Room 217, Honolulu, HI 96822 | (808) 956-7290 - CTAHR Cooperative Extension - Kahului Extension Office
Central Maui extension office offering CTAHR programs for Maui County farmers and gardeners.
310 Kaahumanu Ave., Bldg. 214, Kahului, HI 96732 | (808) 244-3242 - CTAHR Cooperative Extension - Kamuela Extension Office
Extension office in Waimea country serving upcountry Hawaii Island ranchers and vegetable farmers.
67-5189 Kamamalu Road, Kamuela, HI 96743 | (808) 887-6183 - CTAHR Cooperative Extension - Kauai County Office
University of Hawaii CTAHR extension office for Kauai County in Lihue. Its team covers 4-H youth development, the Master Gardener program, edible crops and organic farming, and invasive pest and disease work.
State Office Building, 3060 Eiwa Street, Room 210, Lihue, HI 96766 | (808) 274-3471 Website - CTAHR Cooperative Extension - Kauai Extension Office
Kauai extension office in the Lihue state building supporting island farmers and gardeners.
State Office Building, 3060 Eiwa Street, Room 210, Lihue, HI 96766 | (808) 274-3471 - CTAHR Cooperative Extension - Komohana Research and Extension Center
Hilo research station and extension hub serving east Hawaii Island growers.
875 Komohana Street, Hilo, HI 96720 | (808) 969-8201 - CTAHR Cooperative Extension - Kona Extension Office
West Hawaii extension office in Kealakekua supporting Kona coffee and tropical fruit growers.
79-7381 Mamalahoa Highway, Kealakekua, HI 96750 | (808) 322-4892 - CTAHR Cooperative Extension - Maui County Office
University of Hawaii CTAHR extension office serving Maui in Kahului. It supports local farmers, 4-H youth programs and CTAHR outreach such as booths at Maui AgFest.
310 Kaahumanu Ave., Bldg. 214, Kahului, HI 96732 | (808) 244-3242 Website - CTAHR Cooperative Extension - Molokai Extension Office
Extension office in Hoolehua serving Molokai farmers, ranchers and 4-H families.
526 Huaai Rd, Hoolehua, HI 96729 | (808) 567-6929 - CTAHR Cooperative Extension - Molokai Office
University of Hawaii CTAHR extension office on Molokai in Hoolehua, with a separate mailing box at P.O. Box 394. It serves island farmers, ranchers and 4-H families in Maui County.
526 Huaai Rd, Hoolehua, HI 96729 | (808) 567-6929 - CTAHR Cooperative Extension - Urban Garden Center
Pearl City garden center run by CTAHR extension teaching urban and home gardening on Oahu.
955 Kamehameha Highway, Pearl City, HI 96782 | (808) 453-6050 - CTAHR Cooperative Extension - Wahiawa Extension Office
Central Oahu extension office near Whitmore Village serving Wahiawa farmers and 4-H clubs.
910 California Ave., Wahiawa, HI 96786 | (808) 622-4185 - CTAHR Honolulu Extension Office
Main Oahu Cooperative Extension office on the University of Hawaii at Manoa campus, covering CTAHR outreach for farmers, gardeners and the Oahu 4-H program.
1955 East-West Rd., Ag Sci III Room 217, Honolulu, HI 96822 | (808) 956-7290 - CTAHR Kamuela Extension Office
Cooperative Extension office in Waimea-Kamuela, the ranching heart of the Big Island, offering University of Hawaii CTAHR agricultural help for upcountry producers.
67-5189 Kamamalu Road, Kamuela, HI 96743 | (808) 887-6183 - CTAHR Komohana Research and Extension Center
University of Hawaii CTAHR Cooperative Extension office in Hilo serving East Hawaii growers, ranchers and 4-H families on Hawaii Island.
875 Komohana Street, Hilo, HI 96720 | (808) 969-8201 - CTAHR Kona Extension Office
West Hawaii branch of CTAHR Cooperative Extension in Kealakekua, supporting Kona coffee, fruit and diversified farmers with university research and advice.
79-7381 Mamalahoa Highway, Kealakekua, HI 96750 | (808) 322-4892 - CTAHR Urban Garden Center
CTAHR Cooperative Extension site in Pearl City that offers home gardening and urban horticulture education to Oahu residents.
955 Kamehameha Highway, Pearl City, HI 96782 | (808) 453-6050 - CTAHR Wahiawa Extension Office
CTAHR Cooperative Extension office in central Oahu's Wahiawa, close to the island's main farming district of Kunia and the North Shore.
910 California Ave., Wahiawa, HI 96786 | (808) 622-4185 - Hawaii State 4-H Livestock Council
Incorporated council that runs the State 4-H Livestock Show and Sale, recruits buyers, hosts a livestock judging contest and sets market livestock project rules; no shows were held in 2020 or 2021.
HI Website - Hawaii State 4-H Program
Statewide youth program run through UH Manoa CTAHR with clubs on each island; it oversees livestock projects, county shows and the state show.
Honolulu, HI | 808-956-4106 - Kauai County 4-H
Kauai County 4-H youth program is supported by an Extension educator based in Lihue whose areas include youth development, intergenerational programs and nutrition. It is part of the Hawaii 4-H system run through CTAHR.
Lihue, HI Website - Maui 4-H Livestock Association
Volunteer group that stages the 4-H livestock fair alongside Maui AgFest, giving Maui youth a place to show and sell market animals.
Wailuku, HI - Maui County 4-H Livestock Club
Maui 4-H livestock program covering beef, swine, lamb and goat, plus livestock judging coaching. It runs club training and the To Market and For Breeding show, and Maui members compete at the Hawaii State Farm Fair.
Kahului, HI Website
Guide checked Nov. 11, 2026. Rules and dates change; confirm with the organizer.