The lemon tree, also known as citrus limon, is an evergreen tree grown in subtropical regions of the world. The tree reaches a maximum height of 10 to 20 feet and is damaged when temperatures fall below 22 degrees F; fruit and blossoms are killed below 29 degrees F. To produce the maximum amount of fruit, a proper pruning and shocking regimen should be followed. Pruning is selectively removing certain branches, while shocking is removing all the new upright growth from the tree at once.
Prune off suckers as they develop on the trunk. They are bright-green in color and the leaves will be double-lobed, which makes identification easy. Break them off at the trunk, or prune them off with a pruning shears if they have developed woody tissue.
Prune off any damaged or diseased wood all the way back to live wood.
Prune off long and wispy stems. Weak stems under a quarter inch in diameter do not hold fruit well and will break under the load of a lot of fruit.
Prune off any branches and stems that cross through the tree. You want the tree to grow upward and outward to receive maximum sunlight and airflow. Picking fruit is also easier with an open tree.
Step back and look at the shape of the tree. Prune off branches on sides that look "lopsided." If you want the tree to stay below a certain height for ease of harvesting fruit, cut all the branches off above that height. Remember that the tree will grow fast, so prune it back a little farther than the final height you desire.
Remove the water sprouts throughout the entire tree. These are small, thin and upright twigs of new growth. Removing these all at once is referred to as "shocking." This will shock the tree to grow many more of these water sprouts, which grow fast and often produce buds during their first year of growth. While they may not look good visually, their rapid growth allows a larger yield of fruit.