Why do leaves change colour at different rates?

Trent wants to know why trees of the same species, in the same geography, seem to change the colour of their leaves at different rates. He's even noticed differences on branches of the same tree! James Tytko sought to provide an answer, with help from Charles Shi, botanical horticulturalist at the Royal Botanic Gardens, Kew. Like this podcast? Please help us by supporting the Naked Scientists