Orchid Society of Pakistan

About Orchids
This section provides information about orchids and articles on growing orchids.

Introduction to orchids
Growing Orchids in the Pakistan Environment
Overcoming the Pitfalls of the Beginner

Introduction to Orchids

What is an Orchid?
The orchid family is one of the largest in the plant kingdom, with at least ,000 native species around the world. In addition, man has produced over 30,000 hybrids by interbreeding, and more are being produced every year. Most of the wild species found in temperate zones grow as terrestrial plants, rooted conventionally in the ground. The majority of cultivated orchids, however, are, or have been bred from, epiphytic orchids.These grow on trees or bushes in tropical or subtropical regions, where the climate is sufficiently mild to enable exposed roots to grow. Epiphytes are air plants; they take nothing from their host tree 'but use it merely as an anchorage. They draw nourishment and water from the air and from humus collected in bark crevices or in the angles of branches. Some epiphytic orchids grow on exposed rocks; these are called lithophytes. Generally, epiphytes have the showiest flowers.

Today, far more hybrids are grown than species, many of which have become very rare. The hybrids are usually easier for the beginner to grow successfully because they are vigorous plants able to tolerate the artificial conditions in the greenhouse and home. However, it would be wrong to ignore the beautiful and diverse species, many of which are now raised from seed in nurseries to maintain their population.

The orchid flower
The orchid flower" has six segments; an outer ring of three sepals and an inner ring of three petals. The third petal is the lip or labellum. It serves as a landing platform for the visiting pollinator and is carefully designed to guide it to the pollen contained at the end of the central structure known as the column. The pollen is covered by a protective cap and is formed into waxy masses called pollinia. After pollination the seed pod develops stem immediately behind the flower.

Orchid cultivation
The compost used for orchids should be as close as possible to its natural food source. For this reason the most widely used compost is made up from bark chippings. Bark on its own is a perfectly good medium for all orchids; it is open and well draining and is slow to decompose. For the beginner it is a very easy compost to work with. However, the food supply is restricted and some additional form of feeding will be required. Orchids can be fed in moderation during the spring and summer growing seasons.

Orchids are usually potted in the spring, although young plants are occasionally potted in the autumn. Repotting will be required every other year. The plants should be kept in pots as small as possible, leaving room after repotting for two years future growth. When potting plants with aerial roots, the roots should be left outside the pot to continue growing. Because of their growth or flowering habits, some orchids are best grown in slatted baskets or on rafts of wood.

Many orchids have a summer growing season followed by a winter resting period. When an orchid is at rest all growth stops and it uses the reserves stored in its pseudobulbs. A resting orchid should be placed in full light and kept mostly dry until the new growth is seen, usually early in the spring. An orchid about to rest may shed some or all of its foliage, depending whether it is an evergreen deciduous or semi-deciduous type.

Orchids need light, but not bright unshaded sunlight; this will quickly scorch their leaves, particularly in a greenhouse. The glass should be shaded from the early spring to the end of the summer, after which full light should be given to ripen the resting plants.

Orchids can be divided into three temperature ranges. The cool-house varieties require a minimum winter night temperature of 1Q°C (50°F) rising to a maximum summer day temperature of 24°C(75°F), with an average growing temperature somewhere in between, depending upon the season and immediate ,weather conditions.

The intermediate varieties require a minimum winter night temperature of 13°C(55°F), with a similar growing average and maximum temperature as the cool-house varieties. The warm-house types require no less than 18°C(65°F) as a winter night minimum, and are often better with 21 °C(70°F). This should rise by at least 5°C(1 OaF) during the day. While a plant is growing it should be watered freely to maintain an evenly moist condition of the compost, which will mai ntain pseudobulbs in a plump state. Humidity should be kept high by damping down the greenhouse or by using humidity trays indoors. Most orchids can be lightly sprayed in summer. Fresh air is also important and should be given at all times.

Propagating orchids
Most orchids can be propagated easily by the amateur. With sympodials the rhizome joining the oldest leafless pseudobulbs can be severed and the bulb potted up on its own. Provided there is a healthy dormant eye, a new growth will appear. The main plant should not be reduced to less than three or four bulbs at any time.

Some monopodial orchids can be propagated by cutting off the top section of the plant, complete with its own root system already growing, and potting it separately. The lower section will often produce new growth. Beginners should wait until they have had success with sympodials before propagating monopodials.

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