Add some green to your outdoor design with this attractive planter box. Roof flashing, readily available at hardware stores, protects your wall from water damage. Make as many boxes as necessary to cover the length of your outdoor wall, or try attaching several at different heights for a lush garden wall.
You Will Need
5/4” x 6” wood boards (teak and cedar are good options — length will vary depending on the size of your wall) / metal L flashing / vinyl guttering / drill with a 3/8” bit and 1/16” bit / sander and sandpaper / 18” metal straps (quantity varies depending on length of boxes; use one for every 2 feet, approximately) / 1/2” wood screws / 1” wood screws / 2” wood screws / 3/4” hex / screws / silicone caulk / stain and/or sealer, as desired / pliers / chalk line / level / L brackets (two for each planter section) / clamps
Before You Begin
If your wall is wood or cement fiberboard, standard exterior wood screws should be sufficient for hanging the planter. If your wall is stone or brick, you will need to use masonry screws.
Choose a Location
Determine the overall placement and desired length of the planter box. Use a chalk line and a level to mark the spot where the top of the planter will be attached.
Prepare the Flashing
Pre-drill holes 1/2-inch from the top of the flashing approximately 12-inches apart, depending on the size of your planter. Use a piece of scrap wood to avoid damage to other surfaces.
Attach the Flashing
Attach the flashing to the wall with wood screws, using the chalk line as your guide. The outside ends should reach the full distance of your planters. Overlap the flashing in the middle as necessary — there is no need to cut it. If your wall is brick or stone, use a heavy-duty masonry drill and bit to create a hole before hanging the flashing; it's easier and safer to drill into the mortar rather the brick itself.
Measure the Wooden Boards
You will need wooden boards long enough to cover the length of the flashing, plus two 4 1/2-inches lengths for each side. Use more than one 5/4" x 6 x 10' board if your planter will be more than 9 feet long. You can choose any kind of wood you have available, including reclaimed wood boards, but if you're buying new teak and cedar are both long-lasting, weather-resistant and rot-resistant choices.
Cut the Boards
Cut the boards to size, creating two 4 1/2-inch lengths for each side of the planter box.
Sand, stain and seal as desired. Let dry completely before proceeding.
Cut the Gutter
Next, cut guttering to the length of the wood boards, less 2 1/2 inches to allow room for the gutter to fit inside the box.
Similar to how you handled the flashing, drill holes along both lengths of the guttering 1/2-inch from the top and 12-inches apart.
Create the Planter Box
If you're making one planter box, clamp the 4 1/2-inch side pieces 1/2-inch from the edge of the long board. Make three pilot holes through the front and side pieces — one in center and two 1-inch from the edge of each side.
Add Wood Screws
Connect the wooden planter pieces with three 2-inch wood screws.
Installing the Planter
Attach the guttering to the back of the long boards using 1/2-inch wood screws 3 inches from the top of the board. Hold the box to the wall in the desired location and mark the wall at the inside of the side pieces with a permanent marker. Attach L brackets to the wall at the marked spot using 2-inch wood screws in pre-drilled holes. Hold the planter in place and attach the planter to the L bracket using 1-inch wood screws.
If You're Installing Two Planters
To create an extra-long wall planter with two boxes, start by clamping one side piece flush to the end of each long board. This will be the center of the overall planter. Drill pilot holes through the front of the long board and into the side piece. Attach with 2-inch wood screws. Attach the guttering to the back of the long boards using 1/2-inch wood screws 3 inches from the top of the board. Attach the other side board on the other end, nearly flush with the guttering—the long board should overlap about a half inch on the sides.
Measure and Mark the Wall
Determine the center of the overall length on the wall. Hold one of the planter boxes in place with the outside edge against the center mark. Hold the box to the wall at the center and mark the wall at the inside edge of the side pieces with a permanent marker.
Attach the L-Brackets
Drill pilot holes at the marked spots, then attach L brackets to the wall using 2-inch wood screws.
Attach the Planter
Hold the planter in place and attach it to the L bracket using 1-inch wood screws. Repeat for the other planter box. The two flush sides should be butted against each other in the center.
Attach Guttering to Wall
Use 2-inch wood screw to attach guttering to the wall.
Creating the Hanger
To create the hangers for additional support, use pliers to bend the metal straps to the shape shown above.
Attach the Hangers
Attach the metal straps to the planter boxes and wall with hex screws.
Use silicone caulk to seal the top of the flashing and wall.
Ready for Planting
Your wall planter is ready to be filled with soil and plants. Try trailing plants that will hang over the edge like trailing rosemary or lobelia, install the planter close to the kitchen and fill it with herbs, or even fill it with succulents.
Make sure to water your planter when the soil is dry, especially during hot summer months.