The call comes in the National Trust’s Natural Childhood report, which warns that children face "natural deficit disorder" as they spend less time outdoors.
The charity has launched a two-month inquiry, taking evidence from play and nature experts on how to "reconnect" children with the natural world. The National Trust will stage a summit on the issue during the summer.
The report says a dramatic change in public attitude to outdoor play is needed and that everyone involved in children’s lives, from parents, to teachers to politicians needs to develop practical ways for children to play outdoors.
Catherine Prisk, Play England director, has welcomed the report and said there are "dozens of ways parents and community groups can act now".
"For example parents could get together and close their street once a month so that their children can play outside," she said.
"Time and again when we ask children what they do in their spare time they say they stay indoors and play on computers. When we ask them what they want to do they say they want to play outdoors."
The area children can play and roam unsupervised, labelled by the report at the "radius of activity" around their home, has fallen by 90 per cent since the 1970s.
Children spend an average of 20 hours a week online, mainly on social networking sites and watch more than 17 hours of television a week, up 17 per cent on figures released in 2007.
Among the top three factors for the decline in outdoor play, according to Prisk, are increased traffic, fear of strangers and fear that neighbours might get upset if their children play outside.
Report author Stephen Moss, said: "The time to act is now, while we still have a generation of parents and grandparents that grew up outdoors and can pass on their experience, and while there remains a determination to do something positive in this area.
"Organisations that have an interest in this area, whether working in our towns and cities or in the countryside, have to connect what they are doing and commit to a long-term approach that really makes a difference."
The report also cites evidence that children’s behaviour and attainment improves when lessons are conducted outdoors.
