(News article for January 29, 2022)
If you’ve been thinking of planting a new citrus tree or have an older one that needs to be fertilized, February is a time to do these things. As you choose what to plant, keep in mind that kumquats are the most cold hardy of commonly grown citrus, followed by satsumas.
To begin training a newly planted citrus tree, cut the trunk to 18 to 24 inches tall. Leave three to four branches on the tree, within the area just under where the cut is made. The branches should be spaced out around the tree and growing upwards rather than towards the ground. At the same time, there should not be a narrow angle between the branches and the trunk.
Our Louisiana Home Citrus Production guide gives a simple rule of thumb for fertilizing trees that have been in the ground for at least a year: Use 1 to 1.5 pounds of 8-8-8 or 13-13-13 per year of tree age, up to a maximum of 12 to 18 pounds at 12 years of age and older. For example, if you planted a citrus tree in 2014 so that it is now 8 years old, you could use 8 to 12 pounds of 8-8-8 or 13-13-13.
I’d recommend going with the lower end of the range if using 13-13-13 (since the concentration of nutrient is higher) and the upper end of the range if using 8-8-8 (since the concentration of nutrients is lower). Of course, you could also use 10-10-10 and go with a rate in the middle.
If you just planted the tree recently, wait until you see it starting to put out some new growth and then apply about one-half pound of one of the mentioned fertilizers.
Mixed fertilizers like those mentioned have a density of about 1 pound per pint, or 1 pound per 2 cups. So, if you need 8 pounds of 13-13-13 for an 8-year-old tree, use 8 pints or 16 cups.
If you think your tree has suffered cold injury in one of our recent cold nights, reduce the amount of fertilizer in proportion to the part of the tree that appears damaged. For example, if you have a 4 year old tree and would therefore normally use 4 pounds of 13-13-13 around the tree, but about half the tree appears damaged, you can reduce the amount of fertilizer to 2 pounds of 13-13-13.
As root systems of cold-damage citrus trees have likely been injured as well, you can divide the total amount of fertilizer up into several smaller applications. Be sure not to fertilize after the end of June, though, since late fertilizer application can predispose citrus trees to cold damage the following winter.
When you fertilize a citrus tree, spread the fertilizer out under the ends of the branches, scattering some in the direction of the trunk (but not right next to it) and some in the direction away from the trunk.
Let me know if you have questions.
Contact Mary Helen Ferguson.
The LSU AgCenter and the LSU College of Agriculture