Brush the deck down with a soft broom to remove any dirt or leaves. This will help prevent particles from building up and damaging the deck. If the deck needs a more thorough clean, use a stronger bristled brush and some water.
A high pressure cleaner will wash away any remaining dirt. Make sure you carefully go over the whole deck. If you're cleaning an older deck, make sure the high pressure cleaner doesn't split or crack the wood. For safety reasons, wear closed shoes, safety glasses and earmuffs. If you don't have a high pressure cleaner, a hose will do.
Mix the deck cleaner with water, making sure you follow the instructions to get the correct balance. Use a measuring cup for accuracy and mix the deck clean with the water thoroughly. Make sure you wear gloves, goggles and a mask when working with deck cleaner.
Dip the deck scrub broom into the bucket of cleaning mixture and start scrubbing the deck. Thoroughly scrub every part of the deck to avoid spotting. Leave the cleaning mixture on for 10–20 minutes, taking care not to get any of the cleaning mixture on your plants.
After you've left the cleaning mixture for no more than 20 minutes, wash it down with the high-pressure hose. Make sure you wash away all the cleaning mixture along with any dirt and grime. Leave the deck to dry.
Now you have a brilliantly clean deck again, all you need to do is put your outdoor furniture or barbecue back where they were. You could also stain or oil the timber to help protect it from the elements.