Amanda Gläser-Bligh sometimes attracts puzzled looks when she goes to water the eight-year-old street tree she has adopted outside her door in Charlottenburg, Berlin.

“I named her Linda the linden,” she says. “Berliners are not always known for being super friendly but most people react really positively when they find out what I’m doing.”

As summer heatwaves intensify across the city, Gläser-Bligh carries about 20 litres of water to Linda once a week during the hotter months. It takes a couple of trips up and down stairs with a watering can to finish the job, but she has noticed the tree is no longer wilting in the summer heat. Linden trees are a hallmark of Berlin, even lending their name to Unter den Linden boulevard. Their mature, dense canopies offer essential street cooling, while their blooms provide vital nectar for local bees.