Citrus trees have unique nutritional needs, requiring a consistent and tailored feeding schedule to support their evergreen nature and heavy fruit production. Consistent fertilization is essential for maximizing fruit yield, ensuring tree health, and preventing common nutrient deficiencies. The primary goal of managing citrus nutrition is to align nutrient availability with the tree’s major growth phases. Understanding when and what to feed these trees is the foundation for a successful citrus growing effort.
Establishing the Seasonal Fertilization Schedule
The standard fertilization schedule for established, in-ground citrus trees typically involves three main applications throughout the active growing season. This rhythm ensures a steady supply of nutrients to match the tree’s physiological demands as it moves from bloom to fruit development. The first application is generally in late winter or very early spring, usually between January and February. This initial feeding occurs just before the first flush of new growth and bloom, replenishing reserves and fueling flowering and leaf development.
The second application should occur in late spring to early summer, around May or June, as the tiny fruit begins to set and swell. This middle application directly supports the tree’s heavy energy demand for cell division and fruit enlargement. Providing nutrients at this stage helps the tree retain a healthy fruit load and supports the continued expansion of the canopy. This timing encourages fruit growth without excessively stimulating new vegetative growth.
A third and final application is generally timed for late summer or early fall, typically in August or September. This late-season feeding helps the tree store carbohydrates and nutrients in its roots and wood, preparing it for the cooler, dormant months. Fertilization must stop completely during the dormant winter period to avoid stimulating soft, new growth highly susceptible to cold and frost damage. Avoiding late-season nitrogen applications also prevents issues like delayed fruit coloring, rough rinds, and reduced fruit quality.
Essential Nutrient Needs and Fertilizer Selection
Nitrogen (N) is the primary required element for citrus, which are considered heavy nitrogen feeders due to their constant production of new leaves and fruit. A mature citrus tree needs a significant annual amount of nitrogen to support its growth and yield. Standard citrus fertilizers are blends with a high Nitrogen content, often appearing in ratios like 8-8-8, 12-12-12, or even higher N formulas.
The Phosphorus (P) and Potassium (K) components, while necessary, are often needed in smaller amounts than nitrogen, especially in established trees. Citrus fertilizers are formulated to address this by having a ratio that favors nitrogen, such as a 5-1-3 or similar N-P-K blend. Potassium is particularly important during the summer months to support fruit size, sugar content, and rind strength.
Citrus trees are highly susceptible to deficiencies in specific micronutrients, notably Iron, Zinc, and Manganese. A lack of these elements often results in characteristic patterns of yellowing between the green veins of the leaves. A complete citrus fertilizer should include these micronutrients to prevent such deficiencies. Growers often use slow-release granular fertilizers for long-term feeding in the soil due to their sustained nutrient availability.
Modifying the Fertilization Approach (Age, Location, and Container Growing)
The baseline three-times-per-year schedule changes significantly depending on the tree’s age and location. Newly planted and young citrus trees (up to four years old) require much more frequent feeding as they focus on establishing a strong root system and frame. These young trees benefit from smaller, more frequent doses, often needing monthly or bi-monthly applications throughout the growing season. This approach ensures a continuous supply of nutrients to fuel rapid development without the risk of root burn from a large, single dose.
Container-grown citrus trees, regardless of age, demand a different fertilization strategy. Frequent watering leaches nutrients quickly out of the potting mix, meaning container trees need significantly more frequent feeding. This is often accomplished by applying a diluted, liquid fertilizer on a weekly or bi-weekly basis during the growing season. Alternatively, a slow-release granular fertilizer can be added to the container mix three to four times a year to provide a constant nutrient stream.
The local climate also influences the schedule, primarily by affecting the winter dormancy period. In temperate zones with a defined dormant season, a strict halt to fertilization from late fall through mid-winter prevents cold-susceptible growth. In tropical or sub-tropical climates where growth occurs almost year-round, the feeding schedule may shift to a more consistent quarterly application. Even in warmer regions, nitrogen applications should be minimized during the coolest months to avoid stimulating new flushes of growth.