Lemon trees grow vigorously, especially the Lisbon variety. If not pruned on a regular basis they will develop a very dense canopy, allowing little light to penetrate into the interior of the tree. Under this condition, the tree will produce few interior blooms and subsequently a small amount of fruit. In addition, pesticide sprays become ineffective because of the inability of the spray to penetrate the dense foliage. Left unpruned, a lemon trees will also become quite tall, making picking difficult.
Other citrus trees like orange and grapefruit are not as vigorous in their growth, and therefore do not need as much pruning as lemons. These trees can be left unpruned without serious consequences. If desired, a large tree can be pruned by simply removing a few of the interior branches to open the tree up to more light. Note: studies have shown that yields are reduced in proportion to the severity of pruning. To rejuvenate an older tree, pruning may range from moderate thinning of the canopy to heavy pruning. This pruning will stimulate a new flush of growth; however, the recovery will be temporary unless the cause of the trees decline has been corrected.
When to prune
The timing for pruning is not critical. After the last piece of fruit is removed for the season, is generally a good time. Citrus like Valencia oranges and some mandarins tend to alternate bear. That is, they produce heavily one year followed by light production the next. In this case, it would be best to prune during the ‘off’ or light year. In addition, if you have the time, it is prudent to remove the dead twigs from a tree. These harbor disease spores which, during a rain, will splash and infect nearby fruit causing the fruit to blemish.
