Power Wash Redwood Fence?

If you can remove a single board, you can the power washer. Choose one that can be replaced reversed if the PW wrecks the weathered finish.

Use bleach to kill what is growing, put it in a garden sprayer, just washing wont do it easily. Bleach then wash and spray before it gets all green again in the future.

Try one of the moss killers that works with natural fatty acids, several come in liquid form that you apply with a garden hose hookup. Kill the moss first - takes about a week for the stuff to work and loosen it up. Then with a broom or similar you can loosen the stuff enough to take it off with a stong hose spray. This reduces the risk of damage to the wood. I haven't tried redwood, but I have "firred" cedar and spruce, and you will almost certainly see a difference in the finish using a high pressure spray.

Use Jomax (a detergent) to clean your fence. Power wash can damage wood.

Correction: power washing *will* damage something as soft as redwood.

There is a zinc compound that is good for moss. I forget what you call it but remember google is your friend.

Jimmie