It is especially important to know the root and the growth cycle of the camellia when considering fertilizing. Because they are comparatively light feeders and surface rooting, more camellias are lost by fertilizing mistakes than by lack of feeding altogether.
Do not fertilize a dormant plant. Camellias are dormant when they are developing buds and blooming. That is, from about September 1 through the blooming period, camellias could be severely damaged or killed if a regular camellia-azalea-rhododendron fertilizer were applied during this time.
However, most competition growers do use a monthly feeding of a bloom enhancing fertilizer during this dormant period. Such fertilizers are called low-nitrogen or no-nitrogen fertilizers and have chemical designations of 2-10-10 or 0-10-10 (nitrogen (N)-phosphorus (K) –potassium (P)).
Do not use ordinary garden fertilizers. Use one especially formulated for camellias and azaleas or cottonseed meal.
Do not fertilize a thirsty plant. Always water thoroughly the day before fertilizing.
Do not fertilize an anemic plant. If leaves are yellow from lack of iron, restore the color with chelated iron feeding(s) before using any regular camellia fertilizer.
Do not fertilize during a heat wave. Camellias have tender roots, and the combination of fertilizer and heat is a dangerous, even deadly, situation.
Fertilize camellias during their growing season. As soon as growth buds appear active, generally when blooming is concluding, the plant can utilize the fertilizer. If a commercial, granular preparation for camellias and azaleas is used, it is safer to use half the recommended dosage and fertilize more frequently. Such granular types are active as soon as they dissolve, so a heat wave developing just after fertilizing could cause severe burning if the greater amount of nitrogen were present. Most growers prefer to use cottonseed meal as a growth fertilizer. This product is less likely to cause burning because its nitrogen is slowly released by bacterial action and does not flood the roots with active nitrogen at any one time. The dosage generally used is 1 T/gallon plant, 2 T/2 gallon plant, 3T/5 gallon plant, and proportionally more for larger plants in the ground. For this locality (Southern California), the first feeding can usually be early in April, followed by two more feedings at 6-8 week intervals. After September 1, switch to 2-10-10 or 0-10-10, if desired.
Most growers incorporate chelated iron into their feeding programs to prevent anemia, promote stronger growth, and enhance bloom colors. Blood meal can also be used, but it is an extremely “hot” fertilizer and should be used very sparingly and only in the early spring.
Thoroughly water in all fertilizers. If in pots, fill pots to the brim twice immediately after fertilizing.