Fruit foragers, from left to right, Antoine Jonniaux, Jo Mair, Simon Palenski and Chloe Waretini pick apples in the Christchurch residential red zone near Avonside Drive.

Christchurch's eastern suburbs are transforming into a "huge orchard" of fruit trees where foragers scrump for apples, feijoas and pears to make into pies and jam.

Community campaigners want to harvest from the 1800 fruit and nut trees in the residential red zone and donate the food to the Christchurch City Mission or local businesses, but in the meantime foragers are gathering the fruit that is going to waste.

As thousands of homes are demolished in the red zone, the majority of trees and shrubs are being retained, creating a forest where houses once stood.

The Canterbury Earthquake Recovery Authority (Cera) has catalogued about 30,000 trees and shrubs in the red zone. The Cera database shows that about 1800 of them, or five per cent, are fruit and nut trees, with over 500 apple trees, 340 peach trees and 246 feijoa trees.

Click here for an interactive map of all the red zone trees and a separate map of all fruit and nut trees.

Edible Canterbury coordinator Matt Morris said many people were making "red zone fruit pies and red zone jam".

"Red zoning is a verb in Christchurch. It means foraging to collect the surplus fruit from that area for personal use. To go red zoning," he said.

"That is nice and I don't think there will be any prosecutions for doing that, but a wider scale project would really make a difference to the wider community.

"Imagine if you could walk into Piko or a shop like that and see red zone jam on the shelf. People would buy that," he said.

"When you have acres and acres of apple trees and pears just rotting on the ground there are lots of opportunities.

"It seems like the most incredible wasted resource at the moment. We are looking at the residential red zone with great interest and curiosity."

Morris said Edible Canterbury was in talks with the Cera to create a harvesting scheme.

"At this time of year there is a bountiful harvest to be had. It is a huge orchard. That is a commercial scale orchard."

Avon-Otakaro Network (AvON) co-chair Evan Smith, who is campaigning to turn the red zone into a reserve, said the fruit trees should be retained.

"There is scope to put a browsing trail through the red zone with walkways where you can pluck fruit from a tree and eat it as you go along," Smith said.

Cera seemed tolerant of people entering the red zone on foot to forage for fruit, he said.

"They seem relaxed about that. They don't mind people wandering through with their dogs and enjoying the green space. There is nothing to stop people plucking fruit from the trees.

"People often revisit their old sites knowing that an old fruit tree is there and collecting it."

A spokesperson for the earthquake authority said if people want to access the red zone, they should contact Cera first.

"Cera's standard position is that it does not encourage the public to access the red zone for food foraging purposes. While Cera won't generally prevent people from enjoying a leisurely walk or cycle through the red zone, people are reminded not to trespass on private property where homes are still located and not to enter secure, fenced areas/construction sites.

"Until dwellings are cleared and the interim land treatment is applied to larger areas, people need to be aware that there are a number of potential dangers, including risks to public health, as well as hazards on many Crown-owned properties."

The spokesperson said they would consider an application from Edible Canterbury for short term access to the red zone for specific purposes.