Rhubarb is best harvested in the spring, just as the stalks are turning red. Pull away the outer leaves by using a sideways pull that will remove the petiole or base of the leaf as well as the stalk. Remove the leafy part, as this is toxic. Young plants should only have a few leaves removed as they are still working on their root system. After two years you can remove up to two thirds of the rhubarb leaves each spring. Rhubarb loves a manure mulch in the summer to keep those roots cool. Keep growing, Marianne Binetti