Sweep off loose debris, such as dirt, dust, leaves and branches with a broom and clean between deck cracks using a slender stick or tool. For concrete and stone patios, remove any weeds that may have emerged in cracks or crevices. Pull them up by hand, if possible, or a use a post-emergent herbicide spray to get rid of them.
Use a garden hose or a pressure washer to remove dirt, dust and other material. Begin at one end of the patio and continue until you have rinsed the entire surface area, removing as much dirt as possible. Set the hose or pressure washer to spray a fan of water to push dirt and debris away faster. Spray between decking boards, eliminating any remaining debris. You can remove any mildew with a formulated deck cleaner available at your local True Value hardware store, or use a homemade solution of 3 quarts water, 1 quart oxygen bleach and ¼-cup of ammonia-free liquid dishwasher detergent. Add this solution to a garden sprayer and apply liberally to the deck’s surface. Let the mixture set for about 10 to 15 minutes before rinsing.
Cover any delicate or fragile ground plants near the deck with drop cloths to protect them when spraying chemicals.
If you use a pressure washer, keep the pressure setting below 1,000 pounds per square inch and hold the nozzle a few feet from the deck to avoid damaging the wood.
Wear safety glasses when using a pressure washer to avoid splashing debris into your eyes.
Remove any insect infestations. Knock down spider webs with a broom and use insecticide spray on stinging insect nests.
Wear safety glasses and gloves when spraying insect nests. Also leave a clear escape path for after spraying so you don’t get stung. Keep children and pets away during spraying.
When the coast is clear, knock down nests with a broom or other long-handled tool and dispose of them.