The conference run by the Tree Council, Trees for Cities volunteers and London Tree Officers Association marked the first year of the Londoners Love Trees scheme to coax locals to plant and survey trees. This has resulted in 22,000 hours of work.
Speakers and delegates at Kew Gardens highlighted the importance of training to improve effectiveness and called for politicians, local authorities and tree professionals to listen more to the concerns of volunteers.
Tree Council programme director Margaret Lipscombe said: "Planting has ranged from street trees to orchards. The result is 23,000 new trees through the initiative and volunteers have called for more tree-planting events.
"There has been a big demand for the tree warden training workshops we have run for volunteers. This has increased the number of wardens at a time when council cuts are beginning to affect the resources that can be devoted to trees."
Training covered tree identification, trees and the law and the best ways to plant and care for trees in challenging urban environments. Volunteers said they wanted future topics on monitoring street trees and pests and disease identification.
"We will do what we can to keep up the momentum. But whether it's more tree planting or more training, we are going to need funding to give volunteers the support they really need," said Lipscombe.
"There is little chance of funding from Defra. But we are pursuing corporate sponsorship of volunteer tree wardens and going to charitable trusts."
Londoners Love Trees is being delivered through the Tree Council, Trees for Cities, the London Tree Officers Association and Barcham Trees, with support from the Greater London Authority and Forestry Commission.