A technique used in Europe, espalier is the training of a hardwood plant to grow along a flat, vertical plane, usually alongside a wall or building. Typically done with a fruit tree, the result can be a work of art. Whether you are a gardener with limited growing space or one with lots of room, the controlled shape of the tree makes maintaining and harvesting the tree very easy.
Decide on the location for your espaliered tree. You will need about 2.1 m (7 feet) of horizontal space. A good location will be south-facing or west-facing, and will have good drainage.
Decide how tall you want your espaliered tree to be. A typical height for an espaliered tree is 1.2 m (48 inches). Cut your posts to your desired height, plus the length you will be setting the post into the ground -- a minimum of 30 cm (12 inches).
Calculate one-third of the final height of your tree. If it will be 1.2 m (48 inches) tall, one third equals 40 cm (16 inches). Hammer a nail near the top of each post but do not hammer it all the way in. Hammer another nail one-third of the tree height from the first nail -- in the example, 40 cm (16 inches) -- and then repeat with a third nail another one-third of the way down. In the example, you will have nails along each post from near the top, at 1.2 m (48 inches) from the soil, one-third of the way down at 80 cm (32 inches) and another third of the way down at 40 cm (16 inches).
Erect one post at each end of your space, setting the pole deep enough into the soil so that it will provide a sturdy support for branches heavy with fruit.
Attach the wire to the nails, creating three horizontal supports for your tree. Make the wire tight and very secure, using your pliers to tightly wrap the wire around the nails. These wires need to be strong enough to support the fruit-laden tree limbs.
Plant your tree approximately 15 to 22.5 cm (6 to 9 inches) in front of the wires, taking into account the final diameter of the trunk. Position the tree so that its two strongest branches are running in the same direction as the wires.
Remove all branches and shoots that are below your first wire, and continue to trim off any new shoots that grow in this area.
Select a branch on each side of the tree to be tied to the first tier of wire. Remove all other branches on the tree between the first and second tier. When the tree reaches the second wire tier, repeat by selecting a shoot for each side, tying it to the second tier wire and trimming off the rest. Repeat when the tree reaches the third wire.
Tie the side branches to its wire as it continues to grow. Trim any shoots growing from the horizontal branch to about four to five inches in length. Continue to trim all new shoots growing out of the main trunk that are not part of your design.