Scrub and clean dirty pots
Soak dirty pots in a tub of water with detergent or a garden disinfectant to lift the worst of any compost stuck on them. The disinfectant will knock out any fungal spores or overwintering pests that have taken to the pot stack for winter refuge.
Take out the pots one at a time, and brush inside and out with a stiff hand brush. Rinse in clean water and stack to dry before putting them back into your clean pot store.