Olveston gardener Margaret Goldsmith said she had wondered if the acre of garden at Olveston was too ''small and domestic'' to be listed by the New Zealand Gardens Trust.
However, that doubt was dismissed when the garden was awarded a five-star rating by the trust, making it a garden of national significance.
''It was a lovely surprise,'' said Sarah Goldsmith, Margaret's daughter and co-worker.
Margaret started working as a full-time gardener at Olveston in 2001 and after she suffered an injury, her daughter filled in during her recovery.
Margaret said her daughter's ''brilliant'' work helped her convince management for the role to be shared.
The working partnership was ''so much better'' and the two bounced gardening ideas off each other.
''We work quite well together, I think, '' Sarah said.
''Yes, our arguments are trivial,'' Margaret said, laughing.
At smoko, the pair debated plant selection and placement, Margaret said.
''She says, `I think you're wrong Mum' - but in the friendliest way.''
The most memorable argument was on where to plant the ''striking blue'' Himalayan blue poppy, Sarah said.
''I wanted it planted pride of place but Mum wanted it tucked away,'' Sarah said.
The blue poppy was difficult to grow and flowered for a short time, Margaret said.
Sarah won the argument and the flower flourished for all to see, Margaret said.
The pair said although the trust had told them a six-star rating was possible it was not a goal, Margaret said.
''We just want the garden as nice as we can make it.'' Sarah agreed.
''The garden has been here for 100 years and it is slowly evolving and we don't want to muck around with that too much.''
Margaret said the garden was open to the public, free of charge, from 9am to 5pm daily so it needed to be a ''rolling garden'', offering something to visitors whatever the season.
Trust chairman Kerei Thompson, of Wellington, said he assessed the garden in November and was impressed with its high quality.
The ''well kept'' garden complimented the home and the impressive woodlands area was a highlight, he said.
Tourism New Zealand asked the trust to create the rating system about seven years ago as a ''Qualmark equivalent'' for garden visiting in New Zealand, so tourists knew the standard to expect when planning a trip, Mr Thompson said.
The four six-star rated gardens listed on the trust website included two in Dunedin, Larnach Castle and Dunedin Botanic Garden.
