Screens act as a filter for your enclosed porch, keeping out much of the dirt, debris and pollutants that might otherwise cover everything. This same filtering action results in an abundance of pollen and fine particles trapped on and in the screen itself. Vacuum to remove many of the fine particles, and then follow up with wet cleaning to remove even more dirt. Clean the screens whenever it's time for a thorough porch cleaning, such as at the beginning of spring and end of autumn, to group the cleaning days into one block of time rather than having to handle the tasks several days or weekends in a row.
Move items such as furniture away from the screens, pushing them toward the center of the porch. Move portable items that are outside around the porch at least 5 feet away to keep them out of your cleaning path.
Vacuum the outside of the porch screens on a dry day, if you can access the area immediately surrounding the porch. Work from the top down, vacuuming with an upholstery brush attachment to loosen fine particles. If you can't reach the highest areas, stand on a step stool or stepladder while working. Vacuum the screens from inside the porch if you're unable to access the area outside easily and safely.
Swap the brush attachment for a crevice tool, and vacuum the corners and edges of the screens from inside the porch.
Hose the screens off from inside the porch, spraying outward. Start from the top, going across and working your way down each screen panel.
Dip a soft-bristled brush into a bucket of warm water. Gently scrub each screen from inside the porch, working from the highest areas downward. Add a squirt of mild dish soap to the water before scrubbing if the screens are quite dirty.
Rinse the screens off with the garden hose, again spraying from the inside out and working from the top down.