The PM's call to 'build, build, build' failed to mention the need to help people to rebuild their existing homes to make them zero-carbon.
The Prime Minister's "New Deal" for recovery from the pandemic in the UK has been criticised for failing to focus on tackling the climate and nature crises.
Boris Johnson spoke of building back "greener" in his speech on the stimulus, which included nods to technology including hydrogen and efforts to build the first long-haul commercial zero-emissions plane.
He restated the UK Government's tree planting targets and said £40 million would be available for local conservation projects to tackle climate change, halt the loss of wildlife and connect people to the outdoors.
But he also promised funding for road schemes and reform of the planning system to make it easier to create new homes on brownfield land and "other areas", though Downing Street insisted there was no change to greenbelt policy.
The PM also referred to "newt counting delays", as symbolic of "red tape" holding up development, which has raised concerns about environmental protections.
There was also no mention of insulating homes, seen as one of the most effective ways to create jobs around the country, cut consumer bills and tackle climate change.
The £40 million green recovery challenge fund will bring forward funding so charities and environmental organisations can start work on projects across England to restore nature and tackle climate change.
The government said the funding would help organisations and suppliers create up to 3,000 jobs and safeguard up to 2,000 more in roles such as ecologists, surveyors and nature reserve staff, as well as in engineering and equipment and seed supply.
There have been widespread calls for a "green recovery", with investment in areas such as home insulation, renewables, projects to restore peatland and meadows, and tree planting.
Friends of the Earth campaigner Muna Suleiman said: "The Prime Minister's speech did little to suggest that he recognises the true scale of the climate and nature emergencies our planet is hurtling towards.
"A green and fair recovery should be the centrepiece of government plans, not some detailing at the very edges.
"Boris Johnson won't build back greener by investing in yet more roads, which will only lock us further into the climate crisis."
Dr Darren Moorcroft, chief executive of the Woodland Trust, said action to restore the natural environment and other green projects would cut carbon and reboot the economy, delivering a "win-win".
And he urged: "Woods and trees belong at the heart of any 'green recovery' worthy of the name. That means protecting what we have as well as striving to increase tree cover.
"It is vital, as the nation strives to stimulate economic recovery, that environmental protections are not relaxed."
Ed Matthew, from The Climate Coalition, said: "The PM's call to 'build, build, build' failed to mention the need to help people to rebuild their existing homes to make them zero-carbon.
"This is the biggest and most important building challenge we face as we seek to tackle the threat of catastrophic climate change.
"A massive retrofitting programme to decarbonise UK homes can boost the economy, create over 200,000 jobs across every part of the UK, and reduce NHS costs."
And Tom Fyans, policy and campaigns director at CPRE, the countryside charity, warned that "deregulating planning and cutting up red tape simply won't deliver better quality places".
"It's already far too easy to build poor quality homes," he said.
"Transferring decision-making power from local councils and communities and handing them to developers is the exact opposite of building back better."
In response to concerns about the fate of the greenbelt in the face of planning reforms, the Prime Minister's official spokesman said: "We've not changed our greenbelt policy.
"What we've announced today will reduce the pressure to build on greenfields by making it easier to build new homes from the regeneration of vacant and redundant buildings on brownfield land."
Emily Beament is the PA environment correspondent.