Citrus cultivation in Louisiana thrives due to the region’s subtropical conditions. Success depends heavily on a tailored feeding schedule, necessitated by the mild, long growing season, heavy rainfall, and potential winter freezes. A strategic fertilization plan encourages robust growth, maximizes fruit yield, and ensures the tree develops the cold hardiness needed to survive occasional deep freezes.
Establishing the Optimal Annual Fertilization Schedule
Mature Louisiana citrus trees use a split-application schedule. The first and largest application should occur in late winter or very early spring, typically between late January and early February, just as the tree is breaking dormancy. This initial feeding fuels the spring growth flush, subsequent flowering, and fruit set, providing the largest dose of the tree’s annual nutrient requirement.
A second, smaller application, often consisting only of a nitrogen source, is typically scheduled for late May or June. This mid-season boost supports the summer growth flushes and helps the developing fruit size properly. The frequent, heavy rainfall common in Louisiana can leach nitrogen from the soil quickly, making this supplemental feeding important for maintaining tree vigor throughout the heat of summer.
The most important timing constraint is the final application, which must be completed by the end of June. Applying fertilizer past this deadline, particularly nitrogen, encourages tender, late-season vegetative growth. This growth will not have time to harden off before potential winter cold snaps, making it highly susceptible to freeze damage. Stopping fertilization early allows the tree to naturally slow its growth and prepare for the winter months.
Essential Nutrient Requirements for Citrus
Citrus trees require a balanced supply of macronutrients, with a strong emphasis on nitrogen for vegetative growth and fruit production. A complete granular fertilizer like a 13-13-13 or 8-8-8 blend is commonly recommended for the main applications. These formulas provide Nitrogen (N), Phosphate (P), and Potash (K), which are necessary for energy transfer, root development, and overall plant health.
Beyond the primary nutrients, micronutrients are frequently deficient in Louisiana citrus orchards, particularly zinc (Zn) and manganese (Mn). Surveys show a high percentage of leaf samples exhibit low concentrations of these elements. Although the soil may contain these minerals, conditions like high pH can prevent the tree from absorbing them effectively, essentially locking up the nutrients.
Because of this uptake issue, soil-applied micronutrients are often ineffective, making foliar application the preferred method for correcting deficiencies like zinc and manganese. A foliar spray involves applying a liquid solution directly to the leaves, allowing the tree to absorb nutrients quickly and bypass the limitations of the soil. This treatment is often timed to coincide with the spring leaf flush, when the tree is actively producing new growth.
Application Techniques and Adjustments for Tree Maturity
The method of fertilizer application should always focus on delivering nutrients to the feeder roots while protecting the trunk from direct contact with the product. Granular fertilizer should be broadcast evenly beneath the tree canopy, starting a few inches away from the trunk and extending out to the drip line. This area is where the active feeder roots are concentrated and can absorb the nutrients most efficiently.
New trees, those planted within the last year, require a different schedule than mature specimens. Fertilization should be delayed until the tree shows signs of new growth, usually around mid-March, and then only a small amount, such as one-half pound of a complete fertilizer, is applied. This prevents fertilizer burn on the sensitive, developing roots.
For established trees older than one year, the quantity of fertilizer is typically determined by the tree’s age, up to a maximum of 12 years. A general guideline is to apply 1 to 1.5 pounds of a complete fertilizer (like 8-8-8 or 13-13-13) for every year of the tree’s age. For instance, a four-year-old tree would receive between four and six pounds of fertilizer annually, split across the early-season and mid-season applications.