Espalier is the practice of growing trees flat against a wall or trellis. Apple trees can be espaliered along fence rows much like grapes in a vineyard to maximize crop production efficiency; or they can be espaliered against a wall or fence in a home landscape to produce fruit while using very little ground space. Apple tree limbs may also be pruned and trained in espalier into artful shapes or living sculptures to create a unique garden focal point.
Use sharp bypass pruners to cut the main, lead stem of a young apple tree during the dormant winter season in the first year after planting. Prune this main stem to just above the point where your espalier pattern or design calls for the lowest side branches to develop; trimming this main stem back will encourage side branching at your desired location. Fill a spray bottle with rubbing alcohol and spray the pruners after pruning each tree, to avoid carrying diseases to the next tree.
Remove all flower buds from the espaliered apple tree in the spring after its first pruning. Use pruners to snip the buds from the stems or pinch them off with your fingers. According to the North Carolina State University Extension, this redirects energy to the growing tree in its earliest years.
Snip the main stem back to just above the second and subsequent branching points in your espalier pattern to encourage side branch formation at those points. Do this in the second and subsequent winters after planting the apple tree.
Tie emerging side branches to your espalier trellis using soft twine in the second and subsequent summers after planting the apple tree. Prune any side branches that emerge growing forward, out of the plane of your espalier pattern, as well as any major side branches that detract from the main framework of your design. Snip these unwanted branches back to their base, with the bypass pruners held parallel to the stem from which the unwanted branch is being cut.
Cut all main vertical stems at the point of their desired height during the summer growing season when the apple tree has reached the full size and shape you desire. Repeat this step---and prune any additional emerging side branches---each subsequent summer season for the life of your espaliered apple tree.