A fence made out of pressure-treated lumber can be stained when the lumber has had a minimum of 30 to 60 days to cure outside after you initially treat it with a clear wood preservative. Treating the wood with a preservative before staining will slow pressure-treated lumber's drying process and keep it from cracking or splintering. Each manufacturer of wood preservative has its own recommendations for how long you must wait to apply exterior stain after applying the wood preservative.
Apply a wood cleaner to the surface of the fence with a pump-up sprayer. Only cover two fence panels at a time. Allow the cleaner to sit on the wood for the manufacturer's recommended amount of time.
Wash the cleaner off of the fence with a power washer or high-power nozzle attached to the end of a garden hose. When using a power washer, set the nozzle to a medium-width spray pattern. A narrow spray pattern will cut grooves into the wood. Allow the fence to completely dry before staining it.
Stir the fence stain thoroughly before you use it. Stain pigment settles to the bottom of the can when it sets for a prolonged period.
Fill a paint tray with stain, and use a 22.5 cm (9 inch) roller pad made for stain applications to roll the stain onto the fence. Cover two fence boards at a time while rolling the stain to avoid drying overlapping marks in the stain. Roll the stain from top to bottom. Use the paintbrush to cover areas that cannot be reached with a roller. Allow the stain to dry overnight.
Touch up areas that did not get completely covered with stain.
Clear stains allow the natural colour of the wood to be seen, semi-transparent stains add colour, but still allow the wood to show through. Solid stains cover the wood and the wood grain, much like a coat of paint.