Repotting: root work without the shock

Repotting is root surgery, and the tree tolerates it well only because it happens at the one point in the year when roots are about to grow fast enough to heal quickly. Lift the tree, clear old soil from the root ball with a hook rather than a jet of water, and comb out roughly a third of the mass, cutting back the thickest roots hardest and leaving the fine feeder roots near the trunk alone. Fresh mix goes in and around what remains, worked into every gap with a chopstick so there is no trapped air. Tie the tree in firmly, water thoroughly until it runs clear, and keep it in shade for two weeks — no feed for a month while the roots re-establish.