She is also a social and political photographer with extensive pre-digital photographic records of life in New Zealand.
One of the benefits of being a garden photographer, and having worked for NZ Gardener magazine for more than 10 years, is the remarkable collection of unusual and special plants, which have been recommended, given, or purchased on her forays.
Working on a book, The Subtropical Garden (1996), for which Gil took the photographs, provided inspiration to develop her own subtropical garden. Occasional frosts prompted her to plant a microclimate - a protective tree canopy to filter light and buffer temperature for the tender subtropicals below. Unusual species in the canopy include Chorisia speciosa with a striking thorny trunk, and Brazilian fern tree Schizolobium parahybum, which looks like a tall, feathery umbrella.
Like mother, like sonGil took up gardening, she recalls, when her late husband, artist Pat Hanly, "bought a boat". She says Pat was not really into gardening but enjoyed painting it. He was from down country, where she says they "mow lawns flat and cut hedges to within an inch of their life". She notes son Ben is a perfectionist with his lawn, but she's not, and observes that "women aren't bothered so much about lawns".
At 80, Gil is vibrant and capable, and has only one day of garden help a week. She employs a good arborist to prune her trees each year, which is apparent in the high standard of her garden.
A farmer's daughter and a greenie, Gil believes in living sustainably. She is pleased to see children growing food at school again. As we wander around her vege beds and fruit garden, she hands me a tropical apricot to try. Other unusual edibles include sea kale and turmeric. She has beautifully espaliered apples, and is keen to find out how to get her pistachio tree to produce nuts. A friend keeps a beehive at Gil's place, which yields an impressive 60kg of honey each year.
Gil says she spends a bit on water, and has a rain barrel off her glasshouse, but is considering getting a large slim-line tank for the side of her house. She says the key to her garden looking its best is to water plants before they are stressed. She feeds her soil with compost from a large three-bin system, and uses liquid comfrey and seaweed. Tree prunings are chipped for mulch.
I wondered if Gil had a favourite garden after many years of photographing them. She says she doesn't "do favourites", but "if people are really passionate about what they're doing, then that's interesting".
She loves to return to gardens to see how they, and their owners, have changed. She mentions Ayrlies in Whitford as a great garden to revisit, as there is always something new to see. She also loves Matakana's Rainbow Valley Farm, founded by the late permaculturalist Joe Polaischer and partner Trish Allen.
Gil sometimes stays at the gardens she is photographing, reiterating that "gardeners are interesting people". That certainly applies in her case and, for me, it was a privilege to spend time with this great gardening family.
Visit the Hanly Gardens at the Heroic Garden Festival February 14-15.