Caring for Citrus
Most of Arizona has an ideal climate for growing citrus. If you have citrus trees, or are thinking about planting some, the following presents some general guidelines on basic citrus care.
Established citrus should be watered every 2 to 3 weeks. During the hottest summer months, we usually water our citrus once per week. To help with drainage and root aeration, it is important to keep the ground below the canopy clear of grass and weeds. Many people dig a shallow basin to the root line which helps hold in water. Newly planted citrus should be watered more often, and we recommend following the guidelines from the nursery where the tree was purchased. We purchased our trees from Greenfield Citrus.
For established citrus, they should be fertilized with a blended citrus food in March, June and September. We use Arizona’s Best brand citrus food with a 13-10-4 blend. The three numbers represent the composition of the fertilizer (nitrogen-phosphate-potash) which is described in more detail in the University of Arizona master gardener manual. Fertilizer can be purchased at any local nursery, and the package contains instructions on how much to use. Young trees have different fertilizer requirements and instructions should be given by the nursery where the tree was purchased. You can view a sample fertilization schedule for citrus through UA’s College of Agriculture.
Suckers, also called water sprouts, should be pruned from your tree as soon as they are found. They usually emerge from the trunk below the graft and will normally grow straight up and contain thorns. Suckers divert vital nutrients away from the the main canopy where the fruit is grown.
Other than suckers, citrus only require light pruning. We usually prune the canopy in spring by removing any dead wood or frost damage. We also look for limbs within the canopy that are growing inward or resting on other limbs. When pruning citrus, always keep in mind that they are large shrubs so they should not be pruned like trees. Also remember the best fruit is produced on the lower half of the tree so avoid heavy pruning of the lower branches.
Protection from the Elements
Citrus are very sensitive to frost. They should not be planted in an area where the average low temperature gets below 25 to 30 degrees. Here in Maricopa County, our winters are mild enough that citrus can survive, but they should be protected during frost warnings. Younger citrus trees are more vulnerable to frost than older, more established trees. When our trees were younger, we protected them by covering the canopy with bed sheets and provided a heat source, such as an incandescent light. Now that our trees are older, larger, and impossible to cover, we flood the soil beneath the trees a day before the expected frost. The additional water helps warm the soil and canopy. For more information about protecting your citrus, please read this excellent article from the UA College of Agriculture.
It is also important to protect the trunk of your citrus trees from Arizona’s intense summer sun. If the trunk is not protected, it can actually get sunburned and severely damage the tree. For younger trees (less than a few years old), loosely wrap the trunk with cardboard or burlap. Gently tie the cover to the trunk allowing room for it to grow and expand over time. When the trees are older, their trunks should be painted with white latex paint diluted 50/50 with water to help reflect energy from the sun. Every year, touch up the trunks to keep them protected.