Plant evergreen trees or bushes that will grow taller than your deck railing. Evergreens are usually dense and retain their green color year-round, making them a natural privacy option for your deck.
Grow vine plants below the deck. The vines will grow up the posts and onto the railings of the deck to create a natural screen. Ivy is an option that grows quickly.
Attach a wall of lattice to the deck railing on the side of the deck where you want more privacy. Plant the ivy or other vine plants to grow up the lattice for additional privacy.
Double the height of the railing in a certain section if you want more privacy for that area. For example, if you have a hot tub on the deck, make a taller railing in that area to block the view.
Replace your deck railing with a privacy fence structure. The structure places the boards right next to one another to eliminate the gaps that are included on a regular deck railing.
Attach bamboo fence sections along the deck railing to block the view. Nail or screw the fencing to the existing deck railing.
Build a pergola structure over your deck. Hang curtains made from an outdoor fabric on the sides of the pergola to provide privacy along the sides.