CAMELLIA CULTURE
by Marilee Gray -
Camellias are the jewels of the shade garden that brighten the winter months with blooms of incredible variation and beauty. It is unfortunate, however, that many people consider camellias difficult to grow, when, in fact, they are very easy to grow once their needs are understood and met. Most camellias don't just die; they are killed by too much TLC or ignorance about what the camellia can and cannot tolerate. Knowing the characteristics of camellias makes all the do's and don't's of their culture readily understandable, so it helps to define their culture in terms of their characteristics.
1. Camellias are shade plants with the exception of the sasanquas that are also known as 'sun camellias.' They thrive in pots in the dappled shade under overhead trees or in the ground if the tree roots are deep and do not compete. If they are in a location where they get some hours of full sun, it is preferable that it be morning sun. Afternoon sun should be limited to the very late afternoon.Indirect light is sufficient for most, but, if the plant is very green and healthy but does not bloom well, it might be that the needed light intensity is lacking; the Elegans family is notorious for this. A very acceptable substitution for natural shade is the artificial shade of lath or screen. Screen that gives 55% shade is generally used for most of Southern California. The hotter areas may do better with 60-70% shade. The shade screen that is knit, not woven, will last longer and be easier to install, so it is worth the extra expense.
2. Camellias need to be moist but not soggy.They are subject to phytophthora, or root rot, a fatal condition that develops from too heavy a soil mix and/or too much water. Phytophthora is almost certain to develop if a camellia is planted in too large a pot. It is virtually impossible to avoid over-watering if it is over-potted. Potting up means moving up to the next larger pot size, not skipping sizes.
Watering should be thorough and as infrequent as possible to keep the soil moist and is determined by prevailing temperature, humidity, rainfall, and wind. Wind is particularly injurious in that it rapidly draws moisture from the leaves and results in a dehydrated root ball. Be attentive to plants under the eves that may not be watered during rains or those that have recently been planted in the ground. Until roots have broken from the root ball into the surrounding soil, the plant is, for all practical purposes, still in a pot and needs to be treated like such.
The moisture retention of the soil mix is easily affected by adding peat moss, a material that will hold several times its weight of water. However, the finer textured peat, the kind that is most commonly available any more, rapidly deteriorates into a soggy mass that is detrimental. For this reason, limit its use to less than 15-20% of the mix, and buy the coarser peat, if available. Additives to make a fast-draining mix are discussed more under item 4.
3. Camellias need acidic conditions. The soil mix, ideally, should be about 6.5 pH. Since many areas of California have alkaline water and, therefore, alkaline soil, the acidity is an important consideration. Acidity is provided in the soil mix by such additives as peat moss and oak leaf mold. Only fertilizers that are formulated for shade, acidic plants (camellias, azaleas, and rhododendrons) should be used during their growing season Miracle-Gro’s 30-10-10 plant food and soil acidifier, when used at half-strength, has shown very positive results. When plants begin to look sickly and do not respond to treatment, it is probably soil alkalinity that is the culprit. At 6.5 pH, the maximum absorption of essential elements is effected; just a little either side of 6.5, the absorption falls rapidly. Plants that show anemia should be treated with a product that contains chelated iron to both acidify and provide the needed iron. The anemia must be corrected before a growth-inducing fertilizer is used.
4. Camellia roots have high oxygen requirements. The soil mix is critical, but there is no magic formula, as long as the mix is 1) acidic and 2) fast-draining. One very successful nursery uses a simple mix of 4 parts sandy loam, 4 parts ground fir bark, and 1 part horticultural perlite. Others start with decomposed granite or sand and add peat moss, ground fir bark, oak leaf mold, redwood compost, perlite, or acidic planting mix to achieve the desired results. For certain, the planting mix will determine the watering frequency because of its moisture retention and draining properties, so gear the watering to the needs of the plant in your mix.
Planting camellias in the ground require that you take precautions to prevent the plant from settling and suffocating. Camellias that have been container-grown will likely not have a tap root. Digging a hole 1 1/2 times the depth of the root ball is sufficient; the roots will not be penetrating deeply where air and oxygen will not be available. Make the hole at least twice the diameter of the root ball, and pack a support cone of the natural, unamended soil in the bottom of the hole so that the top of the root ball extends about 2 inches above the ground level. With the plant in place, fill in around it with loose, amended soil. Use the leftover soil to build a watering basin, and fill it with a coarse, loose mulch, such as medium grade pathway bark. The packed cone prevents the plant from settling, and the raised crown assures plentiful aeration. If the location of the plant is such that it would be standing in water during rainy periods, elevating the plant above ground level is essential. Individual plants can easily be elevated by building a 2-foot square frame of 2 x 8 or 2 x 10 wood that will allow the crown of the plant to be lifted to a safe height.
5. Camellias are surface rooting. They are seriously injured by cultivating around the roots. Mulching is necessary and will accomplish many things; it will control the weeds, keep the roots cool and moist in summer and warm in winter, and help disperse dry fertilizers. Most growers frown on any ground covers around camellias, especially those that are vigorous feeders and invasive.
6. Camellias have a dormant season. About September 1st most camellias go dormant and remain so until after they have bloomed and begin the next growth cycle, about April 1st. This means that they are dormant while they are developing their buds and blooming. Dormant camellias are unable to tolerate fertilizers that produce growth, so it is during this time that many conscientious gardeners kill their camellias by fertilizing. The only type of fertilizer a dormant camellia can benefit from would be those with low or no nitrogen, something of a 2-10-10 or 0-10-10 (nitrogen, phosphorus, potassium) formulation, something intended to enhance blooming. These are not necessary for good blooming, but those who exhibit their blooms absolutely do use these bloom fertilizers because they do improve the size, substance, and color of the blooms. Such fertilizers are best used every 2-4 weeks and at 1/2 the suggested amount.
The dormant season is the best time repot or plant camellias in the ground. October is the very best time, because by then all the plants are thoroughly dormant and the summer heat should be over. Any time during the dormant season would be acceptable for repotting or planting, but the earlier in the dormant season, the better. Those done in October have several months in which to develop roots and adjust before the stress of the next growing season occurs.
7. Camellias are light feeders. This characteristic is another that is responsible for many failures of camellia plants. Like all plants, camellias should not be fertilized when they are thirsty. Water thoroughly the day before fertilizing and prevent a sudden and excessive intake of fertilizer. The growing type fertilizers, those that would be used from about April 1st up to September 1st, are ideally and optimally only about 5-7% nitrogen. Several brands of granular, water-soluble fertilizers exist; however, half of the suggested amounts are recommended. These would be used two or three times during the growing period at 6 to 8 week intervals. Cottonseed meal is the choice of many amateur and commercial growers. It gives an acidic reaction and is ideally formulated for the camellia's needs. It would be also be used at 6 to 8 week intervals until 2 or 3 feedings had been accomplished and at the same feeding rate: 1 T/ gallon can; 2 T/2 gallon can; a tight fist full for an egg can; and proportionally more for those of size in the ground. Some growers give a boost to the spring growth with an initial application of fish emulsion, 1T/gallon of water. This can only be used early in the season before heat threatens, and is followed in 2 to 3 weeks with the regular cottonseed feedings.
Many growers have reported excellent results with Miracle-Gro™ 30-10-10 plant food and soil acidifier. When used as directed in strength and at two-week intervals, it has proven to be too strong for many camellias in Southern California. Results have been very positive, however, when it has been used at half strength, 1/2 T/gallon of water. If such is used, it would be in lieu of other growth fertilizers, cottonseed, etc..
Now for some general comments on camellia culture. Camellias should not be fertilized or pruned during periods of extreme heat; delay such actions until the weather has moderated. If cottonseed meal is used for a growth fertilizer, the use of a chelated iron product will be anemia preventative and color enhancing.
Pruning is essential for all camellias, some more so than others. Pruning is done in consideration of the size and the weight of the expected camellia blooms. It is intended to create space for the bloom to open unobstructed and to develop branches of substance that will support the weight of the blooms. After inside and cross branches have been removed, it is often necessary to thin out the remaining branches. Camellias that have grown without pruning for several years will often have a green canopy over a leafless interior. Pruning to thin out this canopy will bring light into the main structure, activate dormant growth buds, and produce a more desirable plant.
Disbudding is necessary, to some degree, on most camellias to produce exceptional blooms. Sasanquas are prized for their profusion of blooms and are not disbudded. All others that have medium to large sized blooms are disbudded to one terminal bud. Even the small and miniature-sized blooming varieties may need to have some buds removed so that the remaining buds have room to open properly. Varieties that set buds down the stem with the leaves can have a bud left on the third or fourth leaf down from the tip if the bloom is not excessively heavy.
Camellia growers in Southern California are fortunate to have in their own backyard one of the world's renowned camellia nurseries. Nuccio's Nurseries, 3555 Chaney Trail, P. O. Box 6160, Altadena, CA, 91001, has developed many of the most outstanding camellia varieties and has brought many species of camellias from the Orient in recent years. Their efforts have been welcomed by camellia hobbyists.