Espalier is an old English horticultural technique of training hardwood plants to grow against a vertical, flat surface such as a wall or the side of a house, both for functional and decorative purposes. It usually commences when a tree is relatively small so it grows along the framework as it matures. Almost any tree can be trained using espalier, including those that produce fruit. Espalier is ideal for people with limited gardening space, and allows gardeners to maintain and harvest fruit easily.
Measure and mark a 7-foot-wide area on a wall for the espalier tree. Measure a height of 48 inches from the ground with a measuring tape and mark the spot on the wall. Draw a line from the ground to the point to serve as a guide.
Insert the posts in the ground at each corner of the 7-foot-wide space. Push each post 12 inches deep in the soil so it supports the branches and fruit of the tree securely.
Measure up 16 inches from the ground and mark the spot on one of the posts. Extend the mark across to the other post and join toe points to form a horizontal line. Measure another 16 inches upwards from the point and mark spots over the first post. Extend the point to the second post with a horizontal line. Extend a third horizontal line that joins the tops of the posts together.
Hammer a nail over the three points on each post. Do not push the nails all the way through the posts.
Attach wire to horizontal sets of nails so you have three lengths on your wall. Wind the ends of wire tight around each nail and pull it taut before extending it to the adjacent nail. Secure it tight and cut off any excess wire.
Plant a 1- to 3-foot tall tree 7 to 9 inches in front of the wall. Make sure the two strongest branches run in the same direction as the wires. Snip off branches that fall below the last horizontal wire, and continue to trim growing shoots off so no branch grows to a height of 16 inches from the ground.
Select the two strongest branches on each side of the trunk and secure them to the lowest horizontal wire with garden tape. Select and secure the two strongest branches on either side of the tree to the middle horizontal wire. Cut off all branches on the tree that lie between the lowest and middle horizontal wires. Repeat the procedure when the tree's branches reach the highest horizontal wire.