   Growing Citrus in Containers - December 15, 2010 Jeff Schalau, Associate Agent, Agriculture & Natural Resources University of Arizona Cooperative Extension, Yavapai County Citrus are subtropical fruits that have been cultivated and bred to develop many varieties. Citrus does not tolerate freezing temperatures for any extended period. Yavapai County’s prime citrus growing areas are the low elevation areas of Black Canyon City and Congress. However, some citrus varieties can be grown in pots. Over the last 12 years, I have spoken to several people growing citrus in the Verde Valley using large pots that are moved to a greenhouse or sunny indoor patio during the coldest times. Citrus is a genus of flowering plants in the family Rutaceae. They are evergreen trees and shrubs originating in tropical and subtropical southeast Asia and many are thorny. The genus contains numerous natural and cultivated origin hybrids, including commercially important fruit such as the orange, lemon, grapefruit, lime, kumquat, and tangerine. The taxonomy of the genus is complex, but recent genetic evidence supports the presence of only three species, C. maxima, C. medica and C. reticulata, with all the other taxa previously accepted as species being of hybrid origin between these three. All citrus require deep soil having good drainage and container growing allows us to easily manage this. If you would like to try growing citrus in a container, you will need well-lit indoor growing space and a sunny outdoor space that are accessible enough to move containers back and forth seasonally. I would recommend using a large, durable pot with a drainage hole (28 inches or larger). Do not believe people that tell you to omit the drainage hole and to put gravel at the bottom of a pot for drainage – it does not work. It would also be a good idea to consider a drainage tray for the indoor period. I would also avoid ceramic pots because of the need to move the pot and the potential for breakage. A half whiskey barrel may be the most economical pot with adequate space, but drainage will be an issue when indoors. A sturdy hand truck would also be handy for moving it in and out. Citrus trees are readily available from nurseries in Phoenix, Tucson, Yuma and other low elevation areas. Make sure the citrus plant you purchase is labeled with a nursery tag naming the cultivar and in healthy condition. Examples of varieties suitable for containers include 'Improved Meyer' and 'Ponderosa' lemons, calamondins, and kumquats. These are most likely to produce fruit indoors in winter. Other citrus will grow and flower but are less likely to produce fruit. Cover drainage holes with fiberglass screen and partially fill the pot with a high quality, sterile potting soil. Tamp the soil down moderately and place the nursery container inside the pot to check the level of the soil. Allow enough room to irrigate the pot with at least two inches of water. Remove the plant from the nursery pot, place in the center of the container, and add backfill to the original soil level of the nursery pot. Irrigate and add potting soil if settling has occurred. When nighttime temperatures regularly dip below 40 degrees F, the container will need to be indoors. Regular irrigation and periodic fertilization are critical for citrus. Do not over apply nitrogen as this will cause the citrus plant to become leggy and more quickly outgrow available space. If a salt crust is visible on the soil and/or if the edges of the leaves are brown, leach the soil in the container by filling the container with water several times and allow to drain to remove accumulated salts. Citrus can also benefit from the addition of micronutrients such as iron and zinc. Monitor your containerized citrus for insect pests too – especially before bringing it indoors for the winter. Treat as necessary with a least toxic insecticide appropriate for the pest(s) you find. Citrus plants have attractive foliage and produce incredibly fragrant flowers. Growing citrus in containers is not for everyone, but for those with enough space and willing to move large plants back and forth each year, they can be very rewarding. Follow the Backyard Gardener on Twitter – use the link on the BYG website (see link below). If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or e-mail us at cottonwoodmg@yahoo.com and be sure to include your name, address and phone number. Find past Backyard Gardener columns or provide feedback at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/.  |