Outside the Joondalup Family Centre in Perth's northern suburbs, a small wooden cart is laden with lemons, capsicum, celery, black olives, red chillies, curry leaves and parsley seeds.

A sign above the cart (a former change table) reads: "Grow Free — take what you need, give what you can".

It was set up by local music teacher and mother Kathryn MacNeil a year ago, and is one of numerous Grow Free carts around Western Australia based on a movement founded in Adelaide.

The Grow Free cart in Joondalup has been running for 12 months and is well used by the local community. ( ABC Radio Perth: Emma Wynne )

"The idea is to create a place where people can bring their excess local produce, their homegrown produce — it could be food, it could be seeds, it could be seedlings," Ms MacNeil said.

"It's all about sharing, giving what you can, so people can take what they need.

"I'm a really strong advocate for community gardens and community sharing and I love having the opportunity to be part of the Grow Free initiative."

The idea is simple: a cart or table set up in an accessible location where people who grow food can pass on their surplus so it doesn't go to waste, and anyone who wants something is free to take it.

Fruit and vegies donated to the Grow Free Joondalup cart. ( ABC Radio Perth: Emma Wynne )

And there is no obligation to give if you also take, and no expectation of getting something in return for contributing to the cart.

"It's all about giving without expecting to receive anything in return," Ms MacNeil explained.

"It takes away the emphasis from currency and it's more about sharing.

"You are basically taking the things that you have in excess and giving them to people with no expectation of getting something back.

"It's quite revolutionary in some ways because we are such a materialistic culture that we really need to have something in return for what we give.

"This way you have to challenge the way you think about giving things and receiving things."

Olives, celery and parsley on offer at the Joondalup cart. ( ABC Radio Perth: Emma Wynne )

It's also about trust.

Givers are unlikely to ever see where their gift goes or how it is used.

"The stuff that you share, you do just have to trust that they have taken what they need," Ms MacNeil said.

"If someone comes along and they take the whole cart, well, that's not an ideal situation but they may need that whole piece of furniture because they don't have a change table.

"You give it freely without any expectations."

Reducing waste and eating local

For those who give to the cart, many do it because they don't want to waste what they grow in their gardens.

"If you have a lemon tree and you have the lemons, don't let the fruit fall to the ground and go to waste," Ms MacNeil said.

"Pick it off the tree, take it to your local share cart, and then the person looking for a lemon doesn't have to go to the shop and buy a lemon from America, they can take one from their neighbours."

Not just food but also seeds and plants are available at the Grow Free carts. ( ABC Radio Perth: Emma Wynne )

Ms MacNeil has observed that more people are wanting to reduce the environmental impact of buying and consuming food.

"I think people are realising the importance of supporting local produce, reducing our carbon footprint and working with the seasons," she said.

"My broccoli is seeding so I am going to collect the seeds so that my neighbours can grow their own broccoli.

"It's a combination of growing your own food and also working together with the community and sharing what you have got."

Most people find out about their local carts online, and more people are deciding to start their own, either at a community centre, a local business or even in their own front yard.

The most carts are in South Australia where the Grow Free movement started, but interest is increasing around the country.

"If you embrace the idea of giving without receiving, it changes the way you think about everything," Ms MacNeil said.