Fertilizing citrus (Citrus spp.) trees in Texas is not as complicated as it might seem. Most Texas soils only require extra nitrogen for citrus trees. Use a simple schedule to make sure your citrus trees are getting what they need at the right time.
Citrus and Texas Climate
Citrus, including lemons (Citrus limon), grow in U.S. Department of Agriculture plant hardiness zones 8 through 10, which means you can grow citrus in some parts of Texas. Nearly 85 percent of citrus trees grown commercially in Texas are in the Lower Rio Grande Valley, 100 miles south of the Rio Grande River. Outside of the valley, you are at a disadvantage because of periodic freezes, but if you live along the Gulf Coast or in Southern Texas you can successfully grow citrus if you provide your trees with winter freeze protection.
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Citrus and Texas Soil
Citrus trees cannot take in and use all the fertilizer nutrients if they are not planted in soils with an appropriate pH.
The soils in the Rio Grande Valley are well-draining and range from fine, sandy to coarse sandy loams. The soil pH ranges from 7.6 to 8 with ground water typically below 5 feet. The soils are fertile and generally good for growing citrus.
Outside of the valley, you can grow citrus in soil with a pH of 6 to 8 as long as it is not salty or blocked by caliche, a hard layer of lime, calcium carbonate, that is found in many arid soils. Fertilizer will be useless in those circumstances.
Fertilizing Young Citrus Trees
Do not fertilize a newly planted citrus tree until it shows signs of growth. After that, add 1 cup of granular, water-soluble fertilizer containing 8 to 13 percent nitrogen each month through October. The nitrogen content is the first number in the three-number series that is on all fertilizers sold in the U.S. So, look for a fertilizer such as a 13-10-4 product.
Apply the fertilizer in a circle at least 12 inches from the trunk and water it well.
- For 2-year-old trees, apply 2 cups of 8
to 13 percent nitrogen fertilizer once a month from February through October.
- For 3-year-old trees, apply 4 cups of 8
to 13 percent nitrogen fertilizer once a month from February through October.
Alternatively, apply smaller amounts of fertilizer with the first number, nitrogen, ranging from 17 to 21, such as a 21-0-0 ammonium sulfate fertilizer.
- For the first year after the transplant begins to grow, apply 1/2 cup each month through October.
- For 2-year-old trees, apply 1 cup once a month from February through October.
- For 3-year-old trees, apply 2 cups once a month from February through October.
Fertilizing Mature Trees
Use a fertilizer containing 15 percent or less of nitrogen on mature trees that are bearing fruit. Remember, the first number of a fertilizer package shows the percentage by weight of nitrogen.
Apply 1 pound for each 1 inch of trunk diameter each year. Two cups of dry fertilizer is roughly 1 pound.
Alternatively, use fertilizer containing 20 percent or more of nitrogen, the first number on the fertilizer package. In that case use 3/4 pound or less for each 1 inch of trunk width per year.
If you apply the appropriate amount once a year, do it in February. Texas A&M University recommends two applications, two-thirds of the total amount in February and one-third in May. You can also split the application into three applications, once each in February, May and September.
Scatter the fertilizer in a 12- to 18-inch band under the outer spread of limbs. This is where most of the tree's feeder roots are located. Water well after spreading the fertilizer.