The orchid is a very diverse family of plants, with over 20000 catalogued species, it is the largest family of flowering plants. Most species are found in Asia. In one mountain alone, Mount Kinabalu in Malaysia, there are over 750 species! Growing orchids is a very rewarding exercise. A number of genera and varieties are available today that will provide flowers pretty much all year long. A few, such as Phalaenopsis (moth orchid), even have attractive bold foliage and make good house plants.
All plants require the correct amount of light, air, water, food and warmth to grow, and orchids are no exception. Most orchids in cultivation are epiphytes (lives on trees) or lithophytes (lives on rocks), and have a common need for good drainage. Most are grown in pine bark which is specially processed to remove bits of wood and cambium (the twisty pieces of bark). You can either buy bark at most garden centres in the form of a proprietory mix, or from most orchid clubs and orchid shows. Never plant these orchids in soil or in ordinary potting mix.
Orchids are accustomed to grow under tree canopies and will usually require some shading from the midday sun. This can be achieved by placing the plants on a patio where a roof or eave shades from the midday sun; or for indoor plants, next to an East or South-West facing window. For those with more than a few plants, it is worthwhile to invest in a shade house. Orchids that live higher up in the tree canopy usually require more light than those that live lower down. If a plant looks lush, with possibly elongated leaves or stems, it usually means it is not getting enough light. On the other hand, if the leaves look yellowish or grows a reddish tint, it is an indication that the plant is getting too much light. Orchids need the correct amount of light in order to flower, but too much will place the plants under stress and may burn the foliage. The right amount of light will result in good looking plants that flower well.
Plants that live up in trees have a steady supply of fresh air in the form of breezes and the wind blowing through their leaves, stems and roots. For plants that are grown outdoors or in a shade house, the normal flow of air is sufficient, but for plants grown indoors, it is important to keep windows slightly open to allow good air circulation, without being draughty in Winter. Shade houses that normally get wrapped up in plastic during the Winter will benefit from a small circulating fan, and make sure the door is opened on fine days to allow for a change of air.
Watering and Feeding
Orchids require regular watering when they are growing. For most, this is usually during the warmer months of Spring, Summer and Autumn. Water the pot well, making sure that all the bark is thoroughly wet and allow the water to flow out the bottom of the pot. The movement of water through the bark displaces the stale air inside the pot and draws fresh air to into the pot when it drains out. Never sit the pot in a saucer of water as the roots will rot. Amongst orchids, Cymbidiums and Phalaenopsis hybrids are gross feeders. Species orchids, on the other hand, tend to require much less food. Some orchids store food in a specialised stem called a pseudobulb. It is preferable for these orchids to be fed at every watering. A little, often, is best. Those orchids that have very little storage will require watering more often. Some orchids require a dry resting period to initiate flowering. Keeping plants dry enough in winter can not be achieved in New Zealand’s climate unless you provide a roof over your plants.
Orchids are found on all continents except Antarctica, and have adapted to most habitats. Those that come from high altitude forests are very adept at tolerating the cold, while on the other end of the scale, those that come from balmy tropical rain forests prefer to be kept in conditions that resemble their original home. In general, orchids are divided into three broad hardiness categories. Cool growing orchids can be grown in frost free areas (eg. Auckland and north) without additional heating. Most will withstand quite low temperatures in the Winter, as long as they are kept dry. Correspondingly, cool growing orchids are the easiest to grow. Intermediate growing orchids will grow in the summer just like cool growing orchids, but require some heat over the winter. This can be provided, for example, by bringing the plants indoors, using a heating pad or with the aid of a greenhouse. Warm growing orchids require warm conditions all throughout the year, and are best grown in a heated green house or conservatory.
Pest and diseases
Healthy growing plants in ideal situations are relatively disease resistant, so adjusting your growing area to suit your plants will pay dividends. Spider Mite attacks in the summer if plants are too dry, overhead sprinkling can help prevent infestations. If spider mite is a problem leaves develop a lack lustre appearance with a silvery sheen on the underside. Spray with miticide or if you prefer you can use the biological approach and introduce predator mite available from Veg-Gro outlets. Garlic snail can attack the roots and will stunt the growth particularly of small seedlings, they eat the growing tip out of the roots and sometimes shoots as well. Mesurol spray or pellets are useful but do not inhale or handle without protective clothing, Mesurol is very toxic to humans and other animals. Slugs and snails will chew on young shoots and flower buds. Control them with bait. Virus can be transferred from one plant to another by using cutting equipment on different plants. Never use communal secateurs or the like even to cut flower spikes. There is currently no cure and diseased plants (and their pots) need discarding. Use the preventive approach to control scale, as the insects are most active in their juvenile stage and you are least likely to notice them until a major infestation occurs. Spray with oil and insecticide combined in October and February but do not spray when flower spikes have buds showing as it will cause the flowers to be deformed.
For some fantastic Orchid images click here .
Reprinted with permission from the Auckland Orchid Club.