A large planter is an ideal tool for growing trees and other permanent outdoor plants. Large planters have the size to contain the roots of a large plant. Since large planters are constructed very thick to contain the pressure of wet soil, they also have an insulating affect against winter cold and summer heat. You can build a large planter in a number of different ways.
Hypertufa is a simulated stone made from cement, aggregates and peat moss. The stone is porous and textured to simulate tufa stone, which is a limestone that comes from alpine regions. Hypertufa is simple to make and has the texture of a mud pie. Start by building a framework from a wire such as chicken wire. Then layer the hypertufa mixture on the outside of the wire frame. Leave a hole in the bottom for a drainage hole. Mist with water and cover with plastic. Allow the mixture to dry for three days. Then uncover the structure and layer more hypertufa on the inside of the container. Mist the inside of the container, cover and allow to cure and dry. At this point you can fill the container with dirt and plant your plants inside of it.
A concrete container is heavier than one made of hypertufa, but is also sturdier and more insulating. Concrete is a pre-mixed product that consists of cement and sand. You can use concrete to cast building projects by adding water. To cast a planter, create a concrete mold from large cardboard boxes that will nest inside one another. Line the inside of the outer box and the exterior of the inner box with dry cleaning bags so that the cement will not stick to the boxes. Create drainage holes by placing oiled dowel rods in the space between the outer box and the inner box. The oiled dowel rods will slip free of the concrete once it has dried thanks to the oil. Mix concrete, reinforcing rods and water until your mixture is the consistency of cake batter. Then pack the mixture into the outer box until it is level with the top of the dowel rods. Place the inner box inside the outer box. Pack the mixture into the space between the sides of the two boxes. Mist the boxes and wrap in dry cleaning bags. Allow the mixture to cure and harden for three days before pulling the planter out of the boxes.
One of the simplest planters to build is made of wood timbers. To construct a large planter such as this, measure and cut wooden landscaping timbers to the correct size. Then drill two sets of ¾-inch diameter holes in each timber. The first set should be 6 inches from each end of the timbers. The second set should be 12 inches from the ends of each timber. Lay your first set of timbers on the ground as your first '"course" of the planter. Attach them to the ground by running a ¾-inch rebar stake through each end hole and drive each rebar stake 1/3 of the way into the ground. Run a second set of rebar into the second set of holes. Create your second row of timbers by laying them on top of the first set. Offset each timber by 12 inches so that the ends of the timbers meet along the second set of holes. Continue to stack timber rows on top of one another until your planter reaches the desired height. Then saw the rebar off at the top of the timbers so that it is flush with the timber. Fill the planter with potting soil and place plants inside of the planter.