Dishwater and bathwater can be used to give vital support that councils often cannot afford to young trees

Instead of letting your dirty dishwater go down the drain, consider using it to water the trees on your street. That is the message from tree experts, who say survival rates for urban trees could be boosted significantly by volunteers.

Russell Miller, a London-based arboricultural consultant, said: “If you plant trees from good stock, at the right time, and provide enough water, you’d lose almost none prematurely. But get that wrong, and more than half can die.”

Miller says a big issue is that local council budgets often do not stretch to include proper watering, which is critical in the first three years of a tree’s life. “Watering is less sexy than planting. It’s cheaper to replace them,” he said.

New street trees need at least 20 litres of water a week – about two large watering cans – from April to September, especially in hot weather, says Miller. Any tap or grey water, including dishwater, bathwater and water from washing cars, windows and even clothes, is fine, as long as it does not contain bleach.

Tree-planting in England falls 71% short of government target Read more

England’s tree-planting fell 71% short of government targets last year, with just over 2m planted. Last October, the environment secretary, Michael Gove, announced a £60m scheme to plant 10m trees, including 130,000 urban trees. But there are concerns that both the money and trees could go to waste unless the right aftercare is prioritised.

“The idea is not just to plant a million trees, but to establish a million trees,” warned Tony Kirkham, arboretum head at the Royal Botanic Gardens Kew.

Most species of street tree, such as the London plane, are chosen especially for their resilience and tolerance of urban stress. But even these species need years to develop root systems that can find their own sources of moisture among the networks of cables and pipes, and compacted soil under pavements and roads.

“Once street trees get stressed it’s difficult for them to bounce back, they really struggle, and have to rely on rain falling the following year,” Kirkham explained. “If this doesn’t happen, the problem is compounded from year to year.”

Citizen-led projects are making an impact, and some local councils, including Cambridge, Sheffield, Camden, Kingston-upon-Thames, Waltham, Enfield and Richmond, have started social media campaigns, put signs up on trees and sent out leaflets urging residents to water their local trees.

“Councils are hoping for rain, and hoping they’ll survive, but there are heavy losses when it comes to urban tree planting. The public can dramatically improve their chances of survival,” said Kirkham. “Anything we can do to relieve the stress on our trees is a massive bonus, for both our local authorities and our trees.”