The project is part of his ambition to make London one of the world's greenest cities and to cut the city’s dangerously-high pollution levels.
The announcement comes a day after City Hall was forced to issue a city-wide air quality alert, which urged pedestrians and cyclists to seek out less-polluted routes through the city. The warning said pollution would peak yesterday in Westminster, City of London, Hammersmith, Kensington and Chelsea, Kingston and Wandsworth but that moderate pollution would continue until this weekend across 17 London boroughs.
"It’s crucial that Londoners who are vulnerable, such as asthma sufferers, are able to take appropriate measures to protect themselves," Khan said.
Over the next two months a range of organisations – including Trees for Cities and Groundwork London – and thousands of volunteers will plant trees in every London borough.
However the 42,000 planned is less than the two million trees Khan pledged to plant when campaigning for the mayoral election in May 2016, a pledge he appears to have backtracked on since.
New trees planted this winter will include apple trees in a new orchard in Redbridge, black poplars and oaks in Victoria Park in Tower Hamlets, while busy main roads in Hillingdon will have trees planted on streets to help combat traffic emissions and boost air quality.
The Deputy Mayor for environment, Shirley Rodrigues, recently held a Tree Summit with key organisations to discuss ways to work closely to increase the tree canopy in London and plant thousands of trees over the next four years.
Khan said: "I want London to be one of the world’s greenest cities which is why I’ve prioritised this funding to kick-start the delivery of thousands of new trees and to protect and enhance our much-loved green spaces.
"Trees improve our environment and help clean up our toxic air, so despite inheriting no budget from my predecessor, I have worked fast to start a new planting programme and deliver the first batch of more than 40,000 saplings this winter.
"This is the first step in my plans for a major tree-planting programme across London in partnership with businesses and boroughs. I remain fully committed to ensuring that hundreds of thousands of new trees are planted over the next four years."
Projects across London bid for grants last December and successful schemes were awarded funding this week. Many of the trees are allocated to brighten residential streets, boost air quality on busy main roads and maintain London’s many local parks, often as a result of residents’ requests.
Other areas receiving new trees include seven residential estates in Hammersmith & Fulham, a community orchard in Southwark, streets in Brent, Croydon, Havering and Lewisham, parks in Tottenham, and woodlands in Ealing and Barking and Dagenham.
- £50,000 to plant street trees in Sutton, mainly on public highways or in nearby areas of low canopy cover.
- £37,000 to plant at least one tree in every churchyard in the Diocese of London and the Diocese of Southwark.
- £30,000 to support small community charities in Hackney and Haringey, highlighting health benefits of tree planting.
- £13,000 to plant trees on seven residential estates across Hammersmith and Fulham in partnership with Groundwork.
- £13,000 to create three urban community orchards in parks across Redbridge, Ealing and Southwark.
The funding is being delivered under a one-year tree-planting programme. The GLA is currently developing plans for a tree programme for 2017-2020 and will announce further details later this year.