Placing large concrete planters around a deck or patio is a good way to add interest to those area or create some privacy. You can use the planters for trees and large plants because they are sturdy enough to accommodate the larger species. The concrete planters are also heavy enough to stay in place during bad weather. Instead of buying a large and expensive concrete planter--and dealing with transportation of the heavy object--you can make your own distinctive planter.
Build a plywood form using 3/4-inch plywood for the sides and 1/4-inch plywood for the bottom. Make the inner dimensions of the form equal to the outer dimensions of the planter you'd like.
Nail the form together with as few nails as possible because you will have to take the form apart after the planter is finished. One or two nails at each side corner and two nails for the bottom should be fine.
Again using as few nails as possible, build another plywood form to fit inside the first one. Fashion it so its outer dimensions leave 2 inches between it and the larger form.
Apply a generous coating of paste wax to the inside of the larger form and the outside of the smaller form.
Mix the concrete with sand mix and water in a wheelbarrow according to the directions on the package.
Cut the pipe into several 2-inch lengths. Place pipe sections in the bottom of the larger plywood form. These will form drainage holes. A good rule of thumb is to use one pipe section for every 6 inches of length; always use at least one.
Trowel the concrete mix into the bottom of the larger form. Use enough mix to bring the concrete level with the top of the pipe sections. Trowel it smooth.
Center the smaller plywood form on top of the bottom layer of concrete. Position it exactly. Add concrete all the way around in several layers, keeping the inner form centred and tamping the concrete down to remove air bubbles.
Level the concrete around the top of the forms with the trowel. Cover the entire form with a plastic bag to keep it damp. Let it sit for 24 hours.
Take out the inner plywood form. Remove the nails from the outer form and remove the sides. Take the concrete planter off the bottom plywood piece. Recover it with a plastic lawn bag and let sit for about a week to keep it damp while it cures.
Since concrete planters are very heavy, make large ones near the spot you will place them to avoid having to move them when they are finished. The sides and bottom of the concrete planter will be 2 inches thick. For extremely large planters, make the sides and bottom 3 inches thick. A handful of the mixed concrete should hold together without dripping water. Hardware stores have concrete dye you can add to the mix to make coloured planters. After removing them fm the set concrete, clean the form pieces so they can be reused.
Wear gloves, safety goggles, a mask and other protective gear when mixing concrete to avoid skin irritation and dust inhalation.