The tree canopy targets are part of the government's measures to help Canberra adjust to climate change by making the city cooler and more adaptable.

A plan released last year set targets of 30 per cent tree canopy cover by 2045.

But the Greens say the requirements in the latest draft territory plan variation would not meet those targets.

In it, multi-level developments would only be required to include 15 per cent tree canopy.

ACT Greens Planning spokeswoman Caroline Le Couteur said the government must act and plan consistently to ensure the target was met.

"The government's proposed planning rules are not good enough to ensure a suitable future tree canopy," she said.

"They aren't consistent with the tree canopy targets.

Greens leader Shane Rattenbury said the Greens would make sure the government stuck to its ambitious climate change commitments.

"The proposed planning changes won't deliver what has been promised, particularly when it comes to trees," he said.

"We can't let the government fall at the first hurdle and the Greens will be seeking changes.

"Canberrans want to live in a city where trees feature prominently as they provide amenity, habitat and keep the environment cool as the climate warms."

The Greens fear the changes would create localised "hot spots" where urban heat would be more severe.

They said it would create an inequitable situation where high density areas suffered the consequences of fewer trees, while older suburbs enjoyed more greenery.

A government spokesman said the government was committed to meeting the 30 per cent canopy target by 2045. He said the draft variation would help the territory achieve the targets for urban areas.

"The draft variation will lead to significant increases in private open space and planting areas in single dwelling residences, and introduces tree planting requirements for all residential developments," he said.

"These changes will see improved urban tree coverage and green spaces that help reduce urban heat and increase our natural biodiversity and provide more green spaces for Canberrans to enjoy."

The spokesman said more than 17,000 trees would be planted across the ACT over the next four years to enhance our urban forest and help meet the challenge of climate change.