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The International Camellia Society [ TOPICS  ] [ Cultivation Page ] [ Camellia Young Plants ]
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or Optimized Vegetative Growth. by Klaus Peper
Camellia seedlings take 4 to 20 years to first show their flower(s). Cuttings need 2 to 4 years, and grafts 1 to 2. All these young plants should experience optimal conditions for their vegetative growth, in order to get a healthy, vigorous plant in the shortest time possible. Although there are some investigations concerned with the optimal conditions for flowering, I found nothing on vegetative development. Perhaps this question is considered trivial, since all experts and most hobbyists intuitively treat their young plants in a quite favourable way. By far the most important growth promoters are light and temperature. Both are plentiful in summer, but became limiting factors in winter, and should be supplied artificially. I like to share my experience in raising young plants in my basement, under artificial conditions, where I have, hopefully, rather optimal growth.
 Temperature: 25°C I try to keep this temperature constant throughout the year, with only small deviations day and night. Growth rate around 25°C are much better than at the 20-22°C range. I have no experience with higher temperatures around 28°C ( it is more difficult and more expensive ). Somewhere beyond 30°C the plants start to develop heat protection proteins for their survival, instead of proteins needed for growth. The exact border between maximal growth temperature and protective heat reaction is not known.
Light Intensity: 10.000 lux A 150 Watt HID ( High Intensity Discharge ) light source is used for the necessary photo energetic input into the plants. HID, or halide metal vapour lamps, are the only useful light sources for plant growth and have optimal white light for illumination and photography. They are far better and more suitable than any other construction. They are readily available and range from 35 through 3500 Watts. My basement room measures 1.4m x 1.6m, the lamp is 1m above the plant desk. At the plant level the illumination was measured to be 11klux, and some shelf places get 22klux. In the room corners there is still 3klux. For comparison, full sun at noon in June delivered 175klux, and values in the shade were around 22klux. In most artificial situations light is the limiting growth factor. Plants need more light at raised temperatures.. Only HID lamps can provide the necessary high output. To my experience 10klux is more than needed by Camellias, even at 30°C.
Light Duration: 18 hours Long day illumination is beneficial for Camellia vegetative growth. Most long day investigators use 16 hours light per day, and in some plants even 24 hours ( continuous light ). The latter condition was investigated and propagated by Walter E. Lammerts ( Tourje (ed): Camellia Culture, 1958 ) for Camellia seedlings. Since my electric timer was defect last year, I tried the 24h illumination of both seedlings and cuttings. In fact, the plants prospered and had considerable growth rates, however, they had difficulties ( or no necessity ) in embedding chlorophyll, and the leaves kept a yellowish or yellow/green marmoration for many weeks. I now have a new timer and keep the light at 18 hours a day. The leaves are now dark green, and the growth rate not much smaller.
Humidity: 75% The useful range is from 60 to 90%. I have no experience with smaller values in the cultivation room. Values beyond 95% should be avoided since, if applied for a longer period, Camellias have difficulties with their respiration, and the filigran network inside the leaves is filled with water instead of air. Leaves easily look vitreous (like green glass) this way, but recover if the humidity is reduced.
Soil and Water To my experience this is the most difficult factor to control and optimize. In fact, I have lost many newly rooted cuttings due to inappropriate soil and over watering. Unfortunately, there is no clear recommendation on the right substrate, since watering habit is individually different. The art of watering is to keep the substrate neither wet nor dry, but just moist. People with a 'green thumb' learn this within 10 years, other, like me, need 20 years of watering experience. With young plants, problems are exaggerated since pots are small and not water tolerant, and the roots are not yet optimally developed and are most sensitive to excessive water. With planting substrate and appropriate watering get your own experience and never stop to experiment. Starting points for this learning curve are the following substrates:
Fertilization I apply weekly a liquid commercial fertilizer at half or less strength. Any nitrogen accented fertilizer will do. Beneficial for dark green leaves is an additional leave fertilization. Use ammonium nitrate at about 0.5g per liter. Excess salt concentration by over fertilization is indicated by brown or black leave margins or tips. Eventually brown spots occur.
Pest Control The only more serious problem I have incountered in the past were scale insects. Indications for their presence are the occurrence of clear honey dew, which, if left, will be infested by fungus molds. If you see honey dew on a plant, be sure to detect at least one scale insect by close inspection. Location of honey dew and insect seem to be unrelated. You can kill the detected insects, however, you will miss the young minute crawlers. Thus I have applied a systemic insecticide (Metasystox Bayer), and have no longer signs of insects the last two month. I believe that an application once or twice a year is sufficient.Surprisingly I had so far no problems with fungus, although temperature and humidity should favour their multiplication. Possibly the rather high light level is beneficial. In any case, as a precaution, should the room and the equipment be kept very clean. Discussion I have now several years of experience with the culture room. The most important steps were:
Plants look now very healthy and vigorous. New growth is stronger and larger than the previous growth. Seedlings may experience two to four growth periods within 6 months, and reach 30cm above ground. Cuttings have usually two growth periods within this time. Between growth periods there are distinct dormancy periods, which become longer when the plant matures (seedlings are more juvenile than cuttings). Dormancy durations vary with different cultivars and also among individual plants from identical parents. Dormancy periods seem to be shorter at high temperatures, high light level and long illumination. Although Camellias love fresh air, it does not appear necessary to install air movement in the closed room, as is recommended for many other plants. Plants may be kept up to 2 years under these artificial condition, perhaps longer, but intuition says that young plants have the individual right to seeing the real world. If new growth is smaller than the previous, or the new leaves appear chlorotic, or even drop after days or weeks, a damage of roots has occurred: they are drowned. Drowning is the most probable reason for Camellia disorder, especially in young plants. If you have this kind of problem, change your potting substrate to one which tolerates better your over watering habit. These are individual experiences in the raise of young Camellia plants. I believe that all conditions are near optimum, and several growth cycles per year help to establish vigorous cuttings, and with seedlings the time to bloom may be considerably shortened. However, this is not a scientific project, where comparisons must be done on a statistically sound basis. If somebody else has made different, or confirming experience, I would be happy to receive comments.
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