Espalier is a landscaping technique from the 16th century still in use today. By planting and pruning trees according to this method, you can grow fruit trees in restricted spaces, such as against a wall or along a fence. You can espalier your trees in either formal or informal patterns. Warm-weather trees, such as citrus, benefit from the additional insulation they get from having their branches flat against a wall. To espalier your young citrus tree, start training it to an informal fan shape in spring.
Install a fan trellis on the wall or fence to support the tree's developing branches and hold them in shape.
Plant your tree 6 inches from the wall or fence in well-drained soil. If you notice construction debris when you dig the planting hole near a wall, remove that topsoil and replace it with composted soil. Align your tree with the trellis' centre.
Cut off all your tree's branches, except for the central leader. Cut the central leader just above a set of buds where you want the first set of branches to develop. According to University of Florida Extension, this should be between 15 and 18 inches off the ground.
Trim all branches after the first growing season, retaining the ones you want to bend into a fan shape.
Tie the branches to the trellis with string to form a fan shape. As new branches develop, either tie them to thicken the fan or, if they aren't in a satisfactory position, cut them.
Examine branches after every growing season, tying or removing new branches to maintain the tree's fan structure.
Water and fertilise your citrus tree as you would if it were in the middle of your garden.