Dendrobium nobile var cooksonianum

Dendrobium nobile was described relatively late, 1830, but after it’s introduction to Europe from China it very quickly became the best known Dendrobium. It is found over a very large range, from the Himalaya regions of India and China, down through Indo-China into peninsular Thailand. Being a far ranging species it is found in a wide range of altitudes, from around 200 metres to over 2,000 metres. It has been used extensively in breeding many hundreds of hybrids and probably best known for what is called the nobile-type hybrids, bred extensively by Yashimoto Dendrobiums of Japan. The hybrids are produced in a rainbow of colours and the flowers vary nearly as much in size.

The variety cooksonianum has purple blotches in the basal half of the petals giving them an appearance similar to the lips making this a much sought after variety and a well grown plant in full flower is a mass of colour. While several varieties of various colours are known, including nobilius, virginale and sanderianum, to name but a few, this one is my favourite.

Dendrobium nobile is often discussed in regards to the best cultivation for it, a lot of discussion surrounds it’s, at times, nuisance as a high producer of of keikis at the expense of of blooms and how it should be grown to deter them. However, I’ve never really found it be any more likely than other Dendrobium species to produce keikis. My method of cultivation is to increase the temperature around late December, to coincide with the shortest day, as I do with the majority of my Dendrobiums, giving it a night temperature of around 10c at night. This temperature can vary depending on the outside weather by 1c to 3c at night. At this point I increase the amount of spraying and misting, ensuring the compost is moistened as soon as it it dries out. Buds may appear anytime from early winter to spring and the flowers open from late December onwards. Once the plant is in full flower the young growths appear at the base of the canes, it’s important not to increase the water too much at this point as the new growths may rot, especially if the growths are arriving in January and there is a sharp drop in temperatures at night. It’s best to stick to spraying and misting with light moistening of the compost early in the day so the plants dry out before night time. Once the new growths are well under way and are about an inch or two (2.5cm – 5cm) in height water can be gradually increased, ensure that no water gets trapped in amongst the unfolding leaves, if it does then make sure you blot it up with kitchen towel before night. By late March to mid April, depending on when the new growths started, they should begin producing roots and a weak feed can be given once a week or every 10 days, about 1/4 to 1/2 of your your usual strength. It’s important not to feed before the new roots are underway or this can also rot the new growth. During the course of the growing season water and feeding can be increased to your maximum levels, shading applied by mid to late March and humidity increased.

Hopefully, by early autumn the plant will be completing it’s growth for the year. We aim to increase cane size annually, although for several reasons this may not be practicable, it may be that that the plant is already growing at it’s maximum size, in which case we can only aim for canes that equal it’s largest in size. Other factors governing cane size may be that it is recently come into your collection as a purchase or gift etc. in these cases then plants often need time to acclimatise to your own cultivation practices and may not attain full height, this isn’t a worry. In other cases a plant decide to make more growths than it has in the past, in these years then it’s expecting too much to ask the plant to produce it’s usual size, it may need another year to organise itself. Whatever the height of the new cane, completion will be obvious by the appearance of the terminal leaf which is usually considerably shorter than the others and quite unmistakable. It is now time to make the plant ready for the new winter season ahead and flowering season. Fertilising should stop and water reduced gradually through the autumn until late autumn/early winter the plant is once again receiving spraying and misting, temperatures at the time will dictate how much, but compost should be allowed to dry out before being watered again. From early autumn to late winter night temperatures are gradually dropped to around 5c – 6c. Shading should be reduced gradually until it is removed completely when there is little danger of hot sunshine scorching the canes, this will allow the cane to ripen in preparation for flowering. The plants can flower at any time of the year, some plants are known to flower twice per year but the main flowering season is between January and April.

 

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