The cafe on the edge of the Sculpture Garden pond, run by the Keebaughs' catering company The Big Group, will be turned into a "conservatory" filled with vegetable and herb gardens.

And $1 from every meal will be donated to the Stephanie Alexander Kitchen Garden Foundation, which teaches school children to grow and eat their own vegetables.

The Kitchen Garden collaboration will run all summer in the cafe.

Alexander said the partnership had been about 15 months in the making and would help spread the word about the pleasures of growing and cooking food.

"I do feel very strongly about the idea of lovely food in public institutions, I think when you go to a gallery or museum it can only add to the experience if you have the best in what we produce and not the worst," she said.

There were piles of colourful fruit and fresh produce in the cafe and lots of colour in the form of The Big Group's founders Bruce and Chyka Keebaugh, who also star on The Real Housewives of Melbourne.

Chyka Keebaugh, who was sporting "head to toe" Scanlan Theodore with a pink peplum ensemble with matching sunglasses, posed for selfies with fans and cheerfully greeted all comers.

The couple said the emphasis in the cafe was on fresh local produce.

"We're serving only wines from the ACT ... and the same with the food as well," Bruce Keebaugh said. "And we're going to try to produce as much fruit and veg as we can. It's going to be tough."

"Canberra needs to be proud of Canberra," Chyka Keebaugh said.

And were there any plans to push for a more permanent structure for the cafe, which has essentially been a pavilion or tent for many years?

Bruce Keebaugh said they agreed wholeheartedly with the idea of a more permanent home for the cafe but it was difficult to invest the capital without knowing what shape the gallery's second phase of planning would take.

"So ideally, yes, It would be everyone's dream, but it's the same as everything else," he said.

Chyka Keebaugh said the Kitchen Garden partnership was a starting point.

"This is a really exciting thing and I think Canberra will embrace it; everyone's loving the concept," she said.

Gallery director Gerard Vaughan said the challenge for the architects who would design the gallery's second phase of development was to incorporate the Sculpture Garden and cafe into a new building.

"I think this is a wonderful pop-up summer phenomenon. It's incredibly popular, it's got a wonderful ambience. I would like to see this continue as much as possible. But the truth of the matter is that we are going to do a new building," he said.

"It's terribly important that the new building embraces the garden, embraces the concept of growth and greenery and that's a very interesting challenge for the architects."