Allow 24 hours for a power-washed deck to dry before applying a stain, and allow the stain to dry for four hours before applying a second coat if it's needed. After staining the deck, wait a full 24 hours for the deck to dry before using it.
Power-washing a dirty deck allows for greater stain adherence and penetration because it removes the surface dirt and any debris trapped between the floorboards. Power-wash the deck earlier in the day to give it plenty of time to dry. When staining, use a natural bristle brush, and prevent lap marks by keeping the leading edge saturated.