Camellias are long-lived, evergreen shrubs celebrated for their glossy foliage and spectacular winter or spring blooms. These acid-loving plants thrive best when their specific nutritional requirements are met. Proper fertilization is a targeted task linked to maximizing the plant’s health, promoting vigorous new growth, and ensuring a spectacular display of flowers. However, camellias are sensitive to over-fertilization and require a delicate balance to avoid damaging their shallow root systems.
Timing is Key: When to Apply Fertilizer
The best time to fertilize camellias is immediately following the conclusion of their blooming cycle, typically in late winter or early spring. This timing allows the plant to replenish energy reserves spent on flowering and directs nutrients toward developing new vegetative growth. This new growth period is when the plant sets the flower buds for the following year’s display.
Avoid fertilizing camellias while they are in active bloom, as this redirects energy from flower production and can shorten the display. Fertilization should cease entirely by mid-summer, generally no later than July, to prevent tender new growth from emerging too late. This late growth is susceptible to frost damage, which can weaken the shrub before winter dormancy. Young or newly planted camellias may benefit from multiple, light applications of fertilizer during the growing season, while established plants typically require only one to two feedings annually.
Selecting the Right Fertilizer
Camellias require an acidic soil pH, ideally between 5.5 and 6.5, to properly absorb nutrients. The selected fertilizer must be formulated for acid-loving plants. Products specifically designed for azaleas, rhododendrons, or camellias are typically the best choice. These formulations often contain ingredients that help maintain the necessary low soil pH.
The ideal nutrient balance, or NPK ratio, can vary depending on the plant’s age and health goals. For established plants where the goal is maintaining health and promoting blooms, a low-nitrogen, high-phosphorus, and high-potassium ratio is recommended, such as 4-8-8 or 5-10-10. Younger plants that require more overall growth may benefit from a more balanced ratio, like 12-4-8 or 10-10-10, though high-nitrogen formulas should be used cautiously.
The fertilizer should also contain secondary nutrients and micronutrients, particularly iron, magnesium, and sulfur. Iron and sulfur are included in acidifying formulas to help maintain the low pH necessary for nutrient uptake. Slow-release granular fertilizers are preferred over fast-acting liquid types because they provide a steady supply of nutrients over a longer period, minimizing the risk of root burn. Cottonseed meal is an organic option that provides a slow, steady release of nitrogen and other nutrients.
Step-by-Step Application Methods
When applying fertilizer, ensure the soil is moist, as applying fertilizer to dry roots significantly increases the risk of chemical burn. For granular products, spread the fertilizer evenly on the soil surface, beginning at least six inches away from the trunk and extending out to the plant’s drip line. The drip line is the circumference beneath the outer edge of the plant’s branches, where the majority of the feeder roots are located.
Lightly scratch the fertilizer into the top inch of soil or mulch using a hand cultivator, taking care not to damage the plant’s shallow feeder roots. Applying the product on top of a thick layer of mulch can prevent the nutrients from reaching the root zone effectively. After spreading, the area must be thoroughly watered to help dissolve the fertilizer granules and carry the nutrients down into the soil where they can be absorbed by the roots.
Always adhere strictly to the dosage instructions provided on the fertilizer packaging, as camellias are highly sensitive to over-fertilization. Using half the recommended amount is safer than applying too much. If using a liquid fertilizer, apply it as a soil drench around the root zone, often at a half-strength concentration for young plants, to reduce the chance of damaging the root system.
Diagnosing Nutritional Issues
Visual symptoms often signal a nutritional imbalance, with chlorosis being the most common sign. Chlorosis appears as a yellowing of the leaves while the leaf veins remain a distinct green color, which is a classic indicator of iron deficiency. This condition frequently occurs even when iron is present in the soil, because an overly alkaline pH prevents the camellia from absorbing it.
Yellowing that is uniform across the entire leaf, particularly on older foliage, may suggest a nitrogen or magnesium deficiency. Magnesium deficiency is characterized by the yellowing of mature leaves as the plant translocates the nutrient to newer growth. Stunted growth or a failure to set flower buds can indicate a general nutrient shortage. Bud drop before opening may be linked to soil moisture issues or insufficient phosphorus.
Corrective action for a confirmed iron deficiency involves applying chelated iron as a soil drench or foliar spray, which provides the nutrient in a form the plant can readily use. The long-term solution is to address the soil pH by applying elemental sulfur or an acidifying fertilizer to create the slightly acidic environment camellias require for optimal nutrient uptake. Increasing the general fertilizer dose is not the solution for chlorosis and can worsen other issues.