Espalier is a tree growing method that was popular in Europe in the 16th century, and was used in the Middle East even earlier. An espaliered tree is basically trained and pruned to grow flat against a wall or fence. This saves space, and because the tree has branches that are trained in a more horizontal arrangement, the limbs usually produce more fruit than they would if left to grow upright. Once the original structure of the tree has been established, pruning, pest control, and basic care for an espaliered tree are easier than with traditional growing methods.
Use 1-year whips for espalier. A whip is a small unbranched tree, usually sold bare root.
Prepare the planting site along a trellis, wall or fence. Plant the whips about 18 inches away from the trellis, and make a header cut by pruning off the top of the whip so it is about 18 to 24 inches tall. It will look like a small stick in the ground while it is dormant.
Anchor the tree loosely to the support. As the branch buds grow, select branches that fit the espalier design you like, and loosely tie them to the support following your design. For example, if you want a fan shaped tree, train five to seven branches to spread in a fan shape. Trim away everything else that does not contribute to the shape of your espalier design. Begin training limbs when they are tiny and flexible.
Continue pruning and shaping your tree as it grows. Keep it on a flat plane against the support. This means that you will have to prune off branches that grow from the back of the tree against the support, and also the branches that grow outwards from the front.
Keep your espaliered fruit tree short so you can easily reach it. This also benefits the tree by forcing the energy to the lower branches, where the fruit is carried. Check the ties regularly and make sure they are loose. If they become tight as the branch grows, remove them and replace them if necessary. As the structural branches grow, they may need additional support for the weight of the fruit.