Types of Orchids – Growing Orchids
The orchid is a vast race of plants embracing a great many genera, a far larger number of species and innumerable man-made hybrids. It is the man-made hybrids that are now so popular as , particularly those derived from a relatively few species such as cattleya, cymbidium, dendrobium, lycaste, miltonia, odontoglossum, oncidium, paphiopedilum, and phalaenopsis.
Many types of orchids are fairly hardy and grow in ordinary. Some are British wild plants, to be found growing freely in meadows, hedgerows and woodlands, etc. Such orchids are known as ‘terrestrial’ orchids because they grow in the ground like the majority of plants, and a few of the exotic kinds which are cultivated in are also terrestrial. Other orchids, and they are the majority, are epiphytic, ie they have adapted themselves to grow in trees or on rocks and to obtain much of their food from the air or from the plant debris which accumulates in such places. Such plants are not necessarily difficult to grow but they do require a totally different cultural technique from that used for terrestrial plants.
These terrestrial types of orchids are grown in very spongy composts, traditionally in a mixture of osmunda fibre (the fibrous roots of the osmunda fern) and living sphagnum moss. However, as osmunda fibre has become somewhat scarce and expensive, terrestrial orchids will grow in all manner of substitutes including the chopped up roots of other ferns, pulverized or shredded bark or even fragments of polystyrene which provide the necessary firm yet very porous medium to which the orchids can anchor themselves. Different mixtures are used for different genera and experts vary greatly in their personal recommendations. A typical mixture, suitable for many types of orchid, is three parts of chopped sphagnum moss, two parts bark chippings and one p art of perlite or polystyrene granules. For cym oidiums, lycastes and paphiopedilums, which need a firmer more terrestrial type of compost, a mixture could be used of two parts sphagnum moss, one part well rotted beech or oak leafmould, one part of fibrous loam, broken up by hand but not sieved, and one part of perlite or polystyrene granules.
Orchids can be grown in well drained pots or in special baskets. It is not, as a rule, entirely necessary to repot annually. However when repotting is done – usually just as new root growth is starting – no attempt should be made to firm the compost around the roots but it should be carefully inserted all round and between the roots so that there are no open spaces.
Nearly all types of orchids prefer a very humid atmosphere and it is natural for the epiphytic kinds to hang their roots down to collect moisture and food from the atmosphere. Trays of water may be required in the house, if that is where you are growing them, in order to maintain this moisture; paths and stages may need to be wetted several times a day and the plants themselves, sprayed with water. Automatic humidifiers can also be used to keep the air at predetermined levels of humidity.
An alternative, almost essential if you are growing orchids indoors, is a terrarium or plant cabinet, which is a kind of tiny, portable greenhouse that can be kept tightly closed and in which any degree of humidity may be maintained.
Some varieties of orchid want a good deal of warmth but most of the more popular kinds will grow in what is known as an intermediate temperature range, 13-16°C (55-61°F) in winter rising to 16-21°C (61-70°F) in summer. Some of the hardier kinds of orchid will take temperatures at least 3°C below these and the little pleiones are virtually hardy and can be grown in any greenhouse as frost can be excluded from the environment.
Nearly all types of orchids need shade from direct sunshine but few like dense shade. Orchid houses are sometimes fitted with lath shades on the sunny side. These are fitted a few inches above the glass with the spaces between the laths measuring about the width of the laths themselves. Such houses also often have two stagings inside, the upper one of slats to carry the orchid pots, the lower one, a few inches below, solid to take gravel, coarse sand or leca (expanded clay granules) which can be kept constantly moist.
Many orchids form bulb-like stems, known as ‘pseudo-bulbs’, which serve as storage organs and are formed, one in front of another, as the plant grows. Old pseudo-bulbs gradually wither away and are discarded, but when orchids are repotted, the younger back pseudo-bulbs can be detached and potted separately to grow into new plants.
Many types of orchids, particularly those with well developed pseudo-bulbs, have a marked resting season each year when temperatures can be allowed to drop a little and watering can be considerably reduced. Part of the skill in growing orchids well, is in knowing when to rest them, for how long and how much.
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