The mystery of the secret pineapple gardener on the Gold Coast Highway at Mermaid Beach has been solved.

Pineapples are growing along the busy road's median strip, and the Gold Coast City Council and Department Of Main Roads had nothing to do with it!

Simon Fox was a Gold Coast resident who did not want to see the city become a concrete jungle.

"On the Gold Coast there is enough concrete, I was insisting that we try and soften something that is a main thoroughfare in an area we lived in," he said.

Pineapples are thriving on the Gold Coast Highway at Mermaid Beach. ( ABC Sunshine Coast: Bern Young )

"My wife helped me at the time, but I did it just because I wanted to make the place look better in an affordable way and the pineapples are a quirky little plant."

"It took my wife and myself a few months at the time. She would pass me the plants and I would plant them … and we ran back and forward and gave them a couple of drinks. And that's it. They were on their own."

"We put the pineapples in because they are so tough and basically they would survive without any maintenance and attention."

Mr Fox has since moved from the Gold Coast and now lives in Jindabyne in New South Wales.

He said he moved because he was sick of arguing over the state of the city.

"We are responsible for all of the planting on the Gold Coast Highway between Venice Street and Francis Street — on both sides of the fence."

"I just didn't want to whinge, I wanted to do something," he said.

Gardening Australia Host Costa Georgiadis said guerrilla gardening was an act, that if done well, went unnoticed.

"A true guerrilla garden is planted with subtlety. It's planted under the cloak of the day to day,"

"Those pineapples have been there for a while to grow to the position they are, and no one has noticed."

Mr Georgiadis said this was a strong demonstration of how a community could use public space.

"We aren't actually saying let's turn this into a community garden. It's not about that. I think what this is doing is saying this is public space, we can do other things, let's use this as an example and utilise other spaces as well."