A 2017 report found the bush capital had lost 10 per cent of its urban canopy cover between 2009 and 2016.

The report's author, RMIT associate professor Marco Amati, blamed tree dieback and development in Canberra.

But the government is looking to put the bush back in the bush capital, with City Services Minister Chris Steel announcing the program at the government's Yarralumla Nursery on Friday.

"This is the largest program of tree planting this century to renew and enhance our urban forest for generations to come," Mr Steel said.

"We want to make sure we're putting in place trees to help us adapt to climate change."

A lack of tree canopy in urban areas created urban "heat islands", which Mr Steel said could be 10 degrees hotter than suburbs with thicker canopies.

Mr Steel said the government would aim to plant trees in newer areas, like Molonglo or Gungahlin, which had low canopy cover.

But the program would also look at older suburbs, where older trees were reaching the end of their life.

The government would also set canopy targets to ensure the suburbs were getting adequate cover.

"We're going to be taking advice from the experts about which trees we should be planting," Mr Steel said.

Yarralumla Nursery is helping to grow the trees, which will be a mix of native trees and non-native trees which are deciduous but offer wider canopy cover.

"The urban canopy refers to the tree cover and green cover in our city rather than outside of our city in the bushland," Mr Steel said.

"We want to make sure that we're benefiting from the trees in our streets and making it a cooler environment as the climate gets hotter and drier."

Australian National Univeristy associate professor and forester Cris Brack said Canberra had expanded and tree canopy cover had shrunk and was needed to help mitigate the effects of climate change.

"The trees are like great big air conditioners," Professor Brack said.

"Mitigation for human comfort... if you're rich enough, you can have air conditioning units and all sorts of energy intensive ways to make yourself comfortable.

"But if ... you can't afford those things then the value of these trees in mitigating those things are immense."

Professor Brack said canopyless suburbs could be a whole 20 degrees warmer than heavily canopied suburbs.

"The CSIRO has a nice heat island study showing that even within the city, you have localised heat island effects," Professor Brack said.

That study showed examples like one street in Tuggeranong on which there was a 17-degree difference between shaded and non-shaded areas.

He said it was important to plant trees that were fit for purpose, something which required a mix of native and non-native species.

"With the exotics you can get deciduous ones, and that can be a real benefit when you're talking about solar access in winter," he said.

Professor Brack also said the roots of non-native trees sometimes took up less space than native eucalyptus trees, but some native trees had broad canopies.

With Canberra's already broad range of trees, different environments had been created which may no longer cater for native species.

The government said the tree planting program would begin while it prepared an Urban Forest Strategy over the next 12 months, which will "set out a pathway to meet canopy targets".