More than 200,000 trees and hedges have been planted in what council leaders hailed a "significant milestone" towards a target for a million to have taken root in Norfolk by 2025.
But with only two years to go in Norfolk County Council's 1 Million Trees for Norfolk scheme, opposition councillors said the project remains "way behind schedule".
The County Hall project grew from a motion brought to full council by Sandra Squire, a former independent county councillor, in 2019.
It was thought that planting trees will help tackle climate change, provide safe habitats for wildlife and boost people's health and wellbeing.
The first trees in the project went into the ground towards the end of 2020, but council bosses previously admitted the coronavirus pandemic had stalled the scheme.
But council leaders say nearly 210,000 trees and hedgerows have now been planted, including more than 30,000 through a scheme to mark the Queen's Platinum Jubilee.
Eric Vardy, the council's cabinet member for environment and waste, said: "This initiative is about much more than just planting trees.
"It's about addressing the environmental challenges we face and creating a greener, more sustainable future for Norfolk."
The council says money is available for the next planting season in November, while other projects to create new woodland are in the pipeline.
READ MORE: Hundreds more trees on route of Norwich NDR have died
But Steve Morphew, leader of the opposition Labour group, said: "This scheme has wide support but is way behind schedule.
"We also don’t know how new ones that don’t survive are accounted for. It would be a mistake to take these figures at face value without very carefully checking the evidence as the net figure will be far fewer than the 200,000 claimed."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here