The Wessex Orchid Society

Transcription

1 The Wessex Orchid Society November 2014 Magazine

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3 Extracts from a talk given by Ian Parsons to the WOS on 13th Sept 2014 Left: Oda Gail Gettel x Durham Castle x Petit Port Right: Odm Gail Gettel x Durham Castle. There are some 58 species of Odontoglossum, which have now been subsumed back into Oncidium, which together with Miltonias, Miltonopsis, Lemboglossum, and others, comprise the Sub-Tribe Oncidiinae. The Oncidiinae are a large family with over 700 species. They are mostly native to South America and are mostly found growing in cloud forests up in the Andes mountains, a chain of mountains running from Colombia in the north to Peru in the south.. Here moist air from the oceans, particularly the Atlantic, is forced up the mountains, leading to cloud formation, very humid conditions, and plenty of rainfall, the conditions being very wet on the eastern side of the Andes. The temperature also falls with the increase in altitude. Left: Honiton Lace Star "Burnham" AM/RHS Right: Onc Illustre xwilscomitan 3

4 Many are found in Ecuador and adjacent areas of Peru and Colombia, and as the Equator passes through Ecuador there is very little seasonal variation in temperature; and day and night are fairly equal in length. So seasonal variation is just due to variations in the amount of rainfall and moisture available. Successful growing of Odontoglossums involves replicating these natural conditions as far as possible. The best temperatures for growing odontoglossums are between 55 o Fand 70 o F (12-21 o C) They can be grown in an intermediate greenhouse provided that the roots are kept cool in Summer. To achieve cooling of the roots I grow them in a plastic pot but place the plastic pot inside clay pots with holes in the sides (drilled first with a small masonry bit and then a larger one). This lets the air through and I spray the clay pots so that there is cooling as the water evaporates from them. Left: Odontioda Margaret Holm. Right: Oda Durham Blues x St Clements I use reverse osmosis water, which has had all the mineral salts extracted, or rainwater. The plants are watered when they need it using an automatic watering system. It can be up to 4 times a day under extremely dry sunny conditions. Remember that they grow in cloud forests where there is mist much of the time and so they like humid air. I keep the Relative Humidity at about 75% and have automatic sprayers 4

5 which come on when the humidity drops lower. The water has a slightly acid ph value. Growing naturally in cloud forest conditions they do not like too much light. I use 50% shading on my greenhouse. I use Orchid Focus Grow, at N15-P15-K15 a well balanced fertiliser, to avoid having too much potassium for my Odontoglossums. I feed every watering with a dilute feed of 200 parts per million (editor: this equals some 312 microsiemens if you have an ms meter), but flush the pot through with plain water bimonthly. I have used sphagnum moss, which produced healthy roots but doesn t last long and needed changing every year. My main compost now is bark, which I obtain from Peter White, mixed with coconut fibre in the ratio of 2/3rds bark to 1/3rd coconut fibre. Odontoglossums do not like coarse compost and so I use relatively fine bark. I have used perlite and vermiculite to bulk out the compost. When repotting remember that you really need 3 good back bulbs to get the plant to survive. The Relative Humidity is too high for spider mites. I control other insects using Provado in its water diluted form. For infestations I use the rule of 4 - spray four times at four day intervals. Left: Wilsonara Tiger Talk Tango Centre: Oda Ingmar x Durham River Right: Odm wyattianum. All photos by Jonathan Watson Summary of talk by Jonathan Watson 5

6 UNDERSTANDING and READING ORCHID LABELS plants identification. By looking at the label you should find its name, if it is legible; but what else does the label tell you? 6

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8 WOS Autumn Above: Phragmipedium Jersey December Glow grown by Margaret Hart. Top Left: Holcoglossum Kimballianum grown by Alan Sapsard.. Centre left: Stanhopea occulata grown by John Dennis Bottom left: Calanthe sylvatica grown by Alan Sapsard. Below: Phragmipedium hybrid.

9 Show 2014 Above: Cattleya hybrid Top Right: Tony Nappin receiving one of his three awards for best hybrid & species and best in Show from the Mayor of Fareham. Right: Neofinettia (Vanda) Lou Sneary grown by Lynn Smith. Below right: Cattleya hybrid. Below: Bulbophyllum hybrid.

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15 November Notes Extra care must be taken now as we go into the winter, not to over-water the orchids. Some have distinct resting periods, others not so definite. Deciduous orchids need to be kept completely bone dry for the winter months whilst leafless. These include pleiones, calanthes and thunias. Some other orchids need just a partial rest where occasional watering is needed to keep the pseudobulbs plump. These include coelogynes, dendrobiums and cattleyas. Many orchids do not rest at all and require watering throughout the winter. Phalaenopsis are a good example of these. Other orchids actually have their growing season through the winter and need to be watered and fed when the compost has dried out. By kind permission of Burnham Nurseries. 15

16 Cover: Paphiopedilum grown by Alan Sapsard Above: Masdevallia Orange Flame, best hybrid and best in show, grown by Tony Nappin Below: Liparis nutans, best species grown by Tony Nappin.