Prune olive trees to open the tree up and allow in light. Allowing more light into the tree will increase fruit production and make fruit picking easier. There are two basic types of cuts: thinning cuts remove entire branches and heading cuts remove the end of the branch and stimulate growth. Most of the pruning required for olive trees are thinning cuts designed to open up the tree. A few, well placed cuts are better than many small cuts.
Pruning a Young Tree
Prune olive trees in the spring when the weather is dry. Cutting during wet weather encourages disease. The olive fruit grows on one year old wood, so it is desirable to leave 10 to 18 inches of new shoots for fruit production.
After planting, remove all side branches within 3 feet of the ground. If the tree is small, allow it to grow for a year before this initial pruning. This keeps the tree off the ground and allows for easier harvesting.
Prune during the first 3 years only to remove suckers and branches within 3 feet of the ground. Otherwise, allow the tree to grow.
Prune during years 4 to 6 to shape the tree. Unless you desire to keep the tree short and bushy, the vase shape is best for letting in light. Remove interior branches to open up the tree and form the vase shape. Continue to remove suckers and branches below 3 feet.
Control height by removing the tallest branches. Cutting the tree to a desired height will stimulate the tree to grow taller, so this is not a good strategy.
Prune in subsequent years to remove growth that encroaches on the interior of the tree. Keep the tree open so that light can penetrate.
Rejuvenating Old Trees
Prune tall, old and unproductive trees to rejuvenate them. Prune away one third of the tree per year, spreading the rejuvenation process over 3 years.
Cut the tree back to 4 to 5 feet over the course of 3 years. Cut back branches below 5 feet. New growth will form from the bark at the cuts.
Begin the process of shaping the tree again in the fourth year, removing branches to open up the tree and allow light in.