When & How to Trim Citrus Trees in Arizona

In the elementary school I attended in Tempe, Arizona, I was taught about the Five C’s of Arizona. They are: Copper, Cattle, Cotton, Citrus and Climate. For this article, I will be focusing on the fourth C of this list. Arizona’s climate is perfect for growing citrus trees, but not all Arizonans know how to care for them. The biggest mistakes commonly made involve how and when to prune citrus trees. Many people are concerned about WHEN they should prune their citrus trees, though that is not the most important question involved. For some, the answer could be: NEVER! Perhaps a more appropriate question is: why should I not trim my citrus trees?

Why NOT to Trim Citrus Trees

When one Valley resident asked The Arizona Republic’s garden expert when she should trim her citrus trees, this was part of the reply: “Homeowners like to trim their citrus trees for looks. Did you know that citrus trees are actually bushes and their branches naturally grow low to the ground? That’s Mother Nature’s way of protecting the fruit and bark …” Those who have driven by the old groves that still exist in parts of East Mesa may understand this idea of citrus trees as overgrown shrubs. The popular misconception that citrus trees should be trimmed the same way as any other type of tree means a shortened life span for many citrus trees in the Phoenix area. This is why I would like readers to ask themselves why they want to trim them before they wonder about when to prune their citrus trees. Whether the aim is to optimize citrus fruit production or simply to have your citrus trees contribute aesthetically to your yard, you should keep their overall health in mind when trimming.

How to Trim Citrus Trees

Even if done during the most optimal time of year, any pruning done should be very minimal. As Dave Owens, also known as ‘The Garden Guy’ states, “Citrus trees like to be left unpruned. The more foliage and dead wood on the tree, the more sun protection the tree trunk will get.” John Begeman, another gardening expert of Arizona, points out that “more leaves equates to more and better fruit,” and also recommends pruning “only if you must and only using the proper techniques.” As outlined in a 1987 article by Lowell F. True, there is some trimming that may be necessary. Although it is best to leave a ‘skirt’ (branches that nearly touch the ground), it is all right to trim this away just enough to make watering and fertilizing easier. Errant branches may also be trimmed, especially if they rub against other branches. As for the outer foliage, the tree’s silhouette, this may be ‘shaped’ for aesthetic purposes, as long as great care is taken to avoid exposing too much bark of the tree to sunlight. There is only one type of pruning that can and should be done regardless of the time of year, especially if you maintain citrus trees for their fruit: the removal of sucker growth. These suckers are also called ‘water sprouts,’ and will sprout from the trunk or even the roots of the tree. A layman may feel this necessary out of intuition or a desire to make the tree look nice, but in fact there is a good reason behind it. True says: “Be sure to eliminate all suckers arising from below the bud union [which is the site of grafting]. They are from the rootstock variety and will not bear edible fruit. When left to develop, they will take over the top portion causing your named citrus variety to be reverted back to an undesired variety.” One important ‘when’ of pruning involves limbs that have been killed by frost, do not remove this deadwood until after spring growth has started, so you can be sure of the extent of the damage.

When to Trim Citrus Trees in Arizona

The best time of year to trim citrus trees is in the spring. If you trim them between about mid March to early May, the trees are less likely to be harmed by extremes in temperature. Citrus fruit ripens in the late fall, from about November to February for most varieties. Minimal pruning during this harvest time is also acceptable. During the winter there is danger of frost, and during the summer there is the opposite problem. Citrus trees are highly sensitive to sun damage, especially during the hottest months of the year and during the hottest parts of the day. If the tree is not shaded during the afternoon, any bare trunk or branches need to be wrapped or painted (whitewashed) for sun protection. The tree is most vulnerable where it receives direct sunshine in the afternoon: the Southwestern exposure. This is why it is so important not to overprune citrus trees: branches subjected to direct sun will burn, and full exposure to the trunk can kill the tree altogether.

In conclusion, I would like to re-emphasize that knowing when to trim citrus trees is not nearly as important as understanding how to trim citrus trees. The number one rule in knowing when to trim citrus trees is the sun. The number one rule in knowing how to trim citrus trees is minimalism. Remember, they are actually just large bushes.

SOURCES (in order of citation within article): The Arizona Republic: Southwest Gardens, Diana Balazs. The Garden Guy: “Citrus Trees” by Dave Owens. Arid-Southwestern Gardening Information: John Begeman [http://www.ag.arizona.edu/gardening/news/articles/3.30.html], University of Arizona College of Agriculture and Life Sciences. “To Prune, or Not to Prune – Citrus, That is.” Lowell F. True, The University of Arizona College of Agriculture “Citrus in the Home and Garden”