Orchids are easily distinguished, as they share some very evident apomorphies. Among these: bilaterally symmetric (zygomorphic) and resupinate, a petal (labellum) is always highly modified, stamens and carpels are fused and the seeds are extremely small.

orchids

Orchids belong to the most diverse family of plants known to man. There are over 880 genera, 28,000 species and well over 300,000 registered cultivars currently documented. These numbers only begin to tell the true story behind the evolutionary success of modern day orchids. Orchids are the most rapidly (genetically) changing group of plants on earth and more new species have been discovered over the last few thousand years than any other plant group known.
Orchids produce seed pods with literally hundreds of thousands of seed that are released and scattered by the wind. Orchid seeds must establish a symbiotic relationship with a special fungus to survive its first year of life. The fungi gathers water and minerals for itself and the seedling, and the seedling shares its sugars from photosynthesis with the fungus. Only one or two orchid seeds will ever germinate and survive on that perfect crevice or depression that is both moist and has the fungus present. Even then, its chances to survive in the wild long enough to bloom are slim.
To avoid this problem, greenhouse growers sow orchid seeds on moist, sugar-rich, sterile agar, or they cut out growing clumps of orchid cells and place them on the agar. These techniques allow many hundreds of orchid plants to survive to maturity. New and improved hybrids can be mass produced rapidly. This is important as orchids are very slow growing. Many orchids take five to seven years to mature to flowering. You can see why breeding three or four orchid generations could span a person’s lifetime just to get one new hybrid propagated sufficiently for sale.

THE ELEMENTS OF COMPLETE PLANT NUTRITION

The following is a brief guideline of the role of essential and beneficial mineral nutrients that are crucial for growth. Eliminate any one of these elements, and plants will display abnormalities of growth, deficiency symptoms, or may not reproduce normally.

Macronutrients

Nitrogen is a major component of proteins, hormones, chlorophyll, vitamins and enzymes essential for plant life. Nitrogen metabolism is a major factor in stem and leaf growth (vegetative growth). Too much can delay flowering and fruiting. Deficiencies can reduce yields, cause yellowing of the leaves and stunt growth.
Phosphorus is necessary for seed germination, photosynthesis, protein formation and almost all aspects of growth and metabolism in plants. It is essential for flower and fruit formation.
Tropical orchids are no more difficult to grow than other plants, but because most of them are epiphytes (tree dwelling plants) their culture is different from that of other types of plants. British orchid growers failed in the early 1800’s when they attempted to grow tropical orchids under dark, hot, and steamy conditions. They succeeded only when they realized that most tropical orchids grew at higher, cooler elevations and in the upper branches of trees where they got considerable light and perfect drainage.

Lighting:

In the greenhouse, most orchids require some shading to prevent the leaves from overheating. In the home, however, orchids need the maximum light available. Placing them outside under the shade of tall trees during the summer months is very beneficial. Do not place them in full sun, however, or the leaves will burn. Also, do not place the plants on the ground, for insects and slugs (snails) can enter the pots and damage the plants. Pot hangers can be used to suspend the plants from tree branches, chains, strong trees, or other structures.

Temperature:

In the home, placing the orchids in a room with relatively cool temperatures will help guard against dehydration. Most orchids are actually most happy at temperatures below the comfort level of humans, especially at night. Orchid greenhouses are usually maintained at 55-65 degrees at night.

Soil:

Potting mixes for tropical orchids are loose mixtures of organic material such as fir bark (not pine bark), tree fern, osumda fiber, with small amounts of peat, perlite, cork, or charcoal added. The object is to have a mix that drains well, but holds some moisture. Most commercial orchid growers supply ready-to-use orchid mixes in small quantities. Orchids usually need repotting only once every two to three years.

Moisture:

In watering orchids, it is best to soak the potting mix thoroughly and wait until the surface is relatively dry before watering again. Most orchids in fir bark based mixes will need watering no more than once every 5 to 7 days.

Fertilizer:

All plants can be fertilized safely with a water-soluble urea free fertilizer such as Growmore 20-10-20 about once a month. Some orchid growers prefer to mix water-soluble fertilizers weaker than indicated on the package instructions and to use them every second or third watering. Always water before fertilizing and remember that it is best to under-fertilize rather than to over-fertilize. With the lower light and drier conditions in the home, orchids cannot use as much fertilizer as they can use in the greenhouse. Some growers like to increase the humidity around their orchids in the home by using “humidity trays” or trays of wet gravel around or under the plants. Pots should not touch the surface of the water.

Water

One of the big mistakes that people make is over watering their orchids. People assume that since they are tropical plants they need a lot of water and this is not necessarily the case. While they do appreciate the humid environment, over watering can kill them.
The amount of watering necessary depends on the temperature any type of orchid a general rule of thumb is to water once a week. You may want to water more frequently in the summer and a little bit less in the winter. The Cymbidium, Miltonia, Odontoglossum and Paphiopedilum varieties like to be kept with the soil a bit moist even between wanterings while the Ascocenda, Vanda and Phalaenopsis prefer to have their soil become dry in between.

Sources: Carte and colmes, Wikipedia

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