How do you verbs a timber deck? ...
Answers: Some people use a stiff bristled push broom and TSP ( tri-sodium-phosphate, from hardware stores ). Along next to a water hose beside a spray nozzle.
Others will use a pressure washer ( get a low foam cleaner that is to say for pressure washers ), rent one or there are services of those who will come and clean your deck. Where I live at hand are classified ads for this service and some ad in the paw held yellow page.
A power washer with a deck cleaner.
You can rent the power washer or buy one.You can buy cleaner for the wood at wal-mart