If you have a greenhouse, then you must clean it yearly. Remove everything: plants, bags of compost, pots and other equipment. Sweep the whole place out, paying special attention to corners where pests may hide. Scrub the frame (inside and out) and floor with a stiff brush and disinfectant. Wash the glass and scrape out the build-up of algae from under overlapping panes - use a plastic plant-label. Allow the greenhouse to dry before replacing its contents. Be sure to inspect plants for pests and remove dead leaves.
If you don't have a greenhouse, you still haven't escaped your spring-cleaning chores. Scrub pots and containers so they are ready for the new season. Sharpen secateurs, lawnmowers and shears.