Grown for their sumptuous blossoms and glossy evergreen foliage, camellias (Camellia spp.) run contrary to many common gardening expectations. With varieties suited to U.S. Department of Agriculture plant hardiness zones 6 through 10, camellias flower from late fall into early spring -- when most plants slow down for winter. Timing camellia fertilizers right is as important as the type of fertilizer you use. Get it wrong, and the plant may not survive. As a general rule, when you see flower buds and lovely blossoms, keep camellia fertilizers far away.
Understanding camellia fertilizer starts with knowing how and when the plants grow. Camellias are shallow-rooted, light feeders that do better with too little fertilizer than too much. To make the most of nutrients in healthy garden soil, camellias need a soil pH near 6.0 to 6.5. In this range, the elements camellias need most stay readily available to the plants. Active camellia growth happens from early spring through late summer, when flowers are not in sight. Camellia blooms appear during their dormant season. Excellent drainage year-round is essential for healthy camellia roots and nutrient uptake.
Most camellia fertilizers should only be applied during active growth. When growth buds plump up and new spring growth begins, it's time to feed. Until blooming ends, the plants can't process nitrogen-containing, growth-stimulating fertilizers. You should generally fertilize camellias three times per season. The first feeding coincides with the start of new growth, and two more feedings follow at six- to eight-week intervals. The final feeding should fall in midsummer. For most home gardeners, these are the only times to fertilize your camellias. Some camellia enthusiasts chase after exhibition-worthy blooms with nitrogen-free bloom enhancers, but garden camellias don't benefit significantly from these.
Garden center shelves are lined with fertilizers for camellias and other acid-loving plants. These fertilizers provide basic nutrients along with extra boosts of iron and other elements camellias get in low-pH soil. Many camellia growers prefer natural, slow-release products instead. Cottonseed meal provides safe, acid-building nutrients for camellias' sensitive roots. For container-grown camellias, use 1 tablespoon of cottonseed meal for each 1 gallon of container size. For example, use 5 tablespoons of cottonseed meal each time you fertilize a 5-gallon container. For landscape plants, use the plant's height as a general guide and use 1 tablespoon for each 1 foot. Spread the meal around the plant's root area, then water well.
Always water camellias well the day before you plan to fertilize, and never let a newly fertilized plant get overly dry. Never use nitrogen-containing fertilizers -- even gentle cottonseed meal -- when camellias are budding or blooming. They'll steal your blooms and injure roots and stems. If you choose water-soluble, fast-release fertilizers over slow-release, organic options, stick with one-half the recommended dose. This is especially important in hot climates. When unexpected hot spells call for more water, those fertilizers release ahead of plan. Extra watering leads to excess nitrogen and fertilizer burn. If high heat is forecast, delay camellia fertilizer or skip the application.