The Basics of Fertilizing Camellias

by Marilee Gray, Claremont, CA –

Camellias are so easy to grow that many people claim that their camellias are beautiful and productive even though they receive no special attention except watering through the dry seasons. Yet others, who are in the conscientious, attentive gardener classification, despair because camellias are so difficult to grow. Their dead and dying camellias attest to their frustration. Why this disparity? The most likely culprit for the latter is their fertilizing program, for camellias survive better on neglect than on too much attention, particularly where fertilizers are concerned. The attentive gardeners, failing to understand the feeding needs of camellias, smother them with tender loving care and succeed only in killing them. An understanding of the characteristics, the likes, and the dislikes of camellias will establish a few basic rules to permit effective and safe fertilizing.

IMG_3085Consider first the nature of camellias: they are acid-loving, surface-rooting, and light-feeding plants that have both distinct growing and dormant periods. These characteristics dictate the three critical factors that must be considered whenever camellias are to be fed: 1) the type of fertilizer, 2) the amount of fertilizer, and 3) the timing of the particular fertilizer. A violation of any one of the three can result in a lethal situation.

The type of fertilizer: Like most shade plants, camellias are also acid-loving plants. Their preferred acidity is something in the 6-6.5 pH range (7.0 pH is neutral); therefore, a suitable fertilizer must have an acidic reaction. They are light feeders, preferring something in the 5-7% nitrogen range for a growth-season fertilizer. This is a meager diet when compared to most fertilizers; lawn fertilizers, for example, contain roughly 35% nitrogen. There are a number of commercial fertilizers that are identified as suitable for “azaleas, camellias, rhododendrons and other shade and acid-loving plants.” Gro-Power (5-3-1) is a similar product that is non-specific for shade plants. All of these products are water-soluble and granular in nature. As such, they have an inherent danger, particularly here in Southern California. Bear in mind that it is the available nitrogen that produces growth, but it is that same nitrogen that will burn if it is present in excess. Therefore, if a heat wave hits shortly after the camellias have been fertilized, the temperature will require that the plants be watered more frequently. If one of these water-soluble, granular types has been used, the more frequent watering will, unavoidably, dissolve and feed the fertilizer at a faster rate than intended. The light-feeding camellias may be severely damaged or killed. To avoid this scenario, it is suggested that such products be used at a rate that is one-half of the recommended dosage to reduce the amount of available nitrogen that can be present at any one time.

Probably all of the commercial growers and most of the amateur hobbyists avoid this danger by using cottonseed meal, a natural organic product that is perfectly suited to camellias. Its percent nitrogen-phosphorus-potassium content designation is 6-3-1. The beauty of cottonseed meal is that the nitrogen is contained in complex organic molecules and is not available to the plant and is not, therefore, capable of burning the roots until bacteria found in the soil have digested the meal and rendered the nitrogen into a usable form. The digestion process increases as the soil temperature increases, but it usually proceeds at such a pace that the roots survive heat spells without fertilizer burn.

A third growth-season fertilizer that is used by a few hobbyists is Miracle-Gro’s 30-10-10 fertilizer and soil acidifier. Its nitrogen content (30) is much higher than that considered safe for camellias in Southern California and caution is recommended. Initial studies have shown that it should only be used at 1/2 T per gallon of water (one-half the recommended amount) and only three to five times during the growing season at two to four-week intervals. Its use should be terminated whenever the foliage becomes excessively large for that variety, an indication that the plant is feeding heavily and is precariously close to becoming over-fertilized. However, its use has been deemed advantageous, particularly in areas where the water and soil are alkaline and unsuited to camellias.

What have been discussed up to this point are fertilizers that can only be used during the growing season. There are other fertilizers that are suited to dormant-season use. The purpose of dormant-season fertilizers is to improve the quality of the blooms; as such, they are used commonly by growers who exhibit camellias, but they are not necessary for the health of the camellia plant. These bloom-enhancing fertilizers have little or no nitrogen and have content designations of nitrogen-phosphorus-potassium of 2-10-10, 0-10-10, or some such formulation with relatively little nitrogen and elevated phosphorus. Here are some examples: Hi-Bloom is a liquid 2-10-10 product; Flower Power is a dry 2-10-10; Super Bloom is a liquid 0-10-10. Studies have shown that the low-nitrogen products are generally more effective than the no-nitrogen products. The effect of phosphorus is seen in the increased brilliance and intensity of the color of the bloom.

The quantity of fertilizers: The rule of thumb that provides a margin of safety is to use only one-half of the recommended amount, regardless of the product being used. For the granular types and cottonseed meal this becomes about 1 T/ gallon-sized plant, 2 T/2-gallon plant, 3 T/3-gallon plant, a tight fist-full for the 4 or 5-gallon plant, and proportionally more for the larger pots and those plants in the ground. Note that the amounts have been given by the pot size; however, if the camellia has been recently potted up, adjust down the amount used. Likewise, since the leaves are the manufacturing stations, if a plant has relatively few leaves for its size, disregard the pot size and use substantially less fertilizer. The varieties of camellias classified as non-reticulata hybrids tolerate less fertilizers than the other camellia species; their suggested feeding rate is one-half of whatever would be given to another plant of that size.  If the liquid dormant season fertilizers are used, apply the same one-half rule and use 1 T/ gallon of water at two to four-week intervals during the bud development and blooming period.

When to fertilize: The correct timing of fertilizing is all-important and is determined by the dormant and growth seasons. Many gardeners fail to understand the significance of these seasons and damage or kill their plants by doing the right thing but at the wrong time. During the seven months from September 1st to April 1st, the time when camellias are developing their buds and blooming, camellias are dormant. This time frame will vary, depending upon the specific variety and the season. If a variety is an early-blooming variety, it tends to go dormant sooner than most; if the season is early, all of the camellias may go dormant sooner than usual. Dormant camellias are not receptive to fertilizers that promote growth; to use a growth fertilizer during this time would be injurious, if not deadly.

When camellias have bloomed and the growth buds begin to lengthen and feather, they are signaling the beginning of another growth phase. Anything labeled as a camellia fertilizer, Gro-Power, cottonseed meal, and Miracle-Gro’s 30-10-10 fertilizer are all growth-inducing fertilizers and are to be used only during the growing season–usually from April 1st to September 1st in Southern California. As before, these dates may vary considerably, depending upon the variety and the season.

The first growth feeding is tied to the onset of new growth. Generally two more feedings follow at six to eight-week intervals, provided the temperatures are not excessive. If a heat wave coincides with a feeding time, delay the feeding until the temperatures have moderated. Pushing for growth during a heat wave only increases the stress of an already stressful situation.

It is generally advisable not to feed a growth fertilizer too close to September 1st. Instead, plan to feed far enough in advance of that date so that the particular fertilizer used will be fairly well consumed by that time and then switch to a dormant fertilizer, if desired. If the size of the developing buds leaves any question as to whether or not another feeding of a growth fertilizer can still be given, play it safe and switch to one of the dormant fertilizers instead. Be observant and adaptable and apply fertilizing schedules according to the season, not the calendar.

A number of variations on a basic fertilizing program can be tried. Camellias show a heftier flush of growth if the initial feeding is one of fish emulsion (1 T of the 90+% concentration per gallon of water). Fish emulsion is a ‘hot’ fertilizer that reacts quickly and can only be safely used early in the season when heat would not be expected. This can be followed in two to three weeks with cottonseed meal at six to eight-week intervals. Additionally, better growth and blooms result if, instead of straight cottonseed meal, a mixture of four parts cottonseed, one part blood meal, and one part chelated iron is used. Such an iron-containing mixture prevents anemia and gives the leaves a rich green color; it also produces more radiant colors in the blooms. If a camellia shows anemia (the leaf veins are a darker green than the pale color between the veins), it must be corrected with feedings of a chelated iron product before any growth fertilizer is used. Repeat the iron treatment, as necessary, until a healthy green color is restored.

Apply dry fertilizers evenly around the drip line and use water to drill it through the mulch material. Cottonseed meal can also be chucked into the side of a pot and watered lightly to form a hard cake. This cake will then break down slowly, and watering will provide an even, slow feeding.

Liquid fertilizers or those that are dissolved in water before using can readily be applied with watering if a proportioning siphon is used at the faucet. Each gallon of solution to be diluted contains the amount of fertilizer that will be dispensed; i.e., when using a 1:15 proportioner, each gallon of concentrated mix contains the fertilizer needed for 16 gallons of water with fertilizer.

Here are some general fertilizing tips. Do not fertilize a thirsty plant; it should be thoroughly watered the day before it is fertilized. Do not let a recently fertilized plant go dry; burning will likely occur. If using liquid fertilizer solutions, add portions until the solution drains from the pot holes.

This has been a brief discussion of fertilizing camellias for the beginner. Let me add one more bit of advice. You would not change the cart axle if it isn’t broken; neither should you change your camellia culture if your plants are healthy and are producing good blooms. If you are winning, disregard all of this and stay with your winning ways!

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