Orchids

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Scientific Name

I. Botany/History

  • Family: Orchidaceae
  • Growth Habit: Most orchids in cultivation are epiphytic, growing upon trees, rocks, and decomposing material instead of rooting into the ground. They have fleshy roots and stems that have a white coating called velamin. This coating helps to absorb water and nutrients. There are thousands of orchid species, highly variable in their requirements. Each species requires a different balance of temperature, humidity, light, water, fertilizer, media, ventilation, etc.
  • Origin: Native orchids have been found growing on every continent except Antarctica. New species are being discovered all of the time. *Development: In 1789, the Royal Botanic Gardens were cultivating 15 species. During the folling 50 years, orchid mania swept over Europe.
  • Key people: Currently, the major countries from which U.S. companies import orchids from are Taiwan, Thailand, and the Netherlands. The U.S. usually has mature plants shipped in from these and other countries for potted plant sales. Cut flower producers usually maintain their own crops, since plants are long lived and bloom seasonally. However, this seasonality of bloom lowers crop prices because certain species go onto the market in mass.


II. Uses

  • Pots: Potted orchid plants are becoming increasingly popular in nurseries and retail stores alike.
  • Cut flowers: Orchids are used by florists in arrangements, corsages, and wedding bouquets for an elegant and unique look. While orchids comprise only 8% of the market in sales of wholesale cut flowers, this still earns them a place in the top 10.
  • Bedding plants: Orchids are used as bedding plants in tropical areas.


III. Propagation

  • Sexual: This is usually done through seed embryo culture, because orchid seed is very minute and devoid of stored food for seed germination. Orchid and fungi have a symbiotic relationship during germination: certain fungi will infect orchid seeds and help convert complex starch to simple sugars, which serves as an energy source for both organisms. Studies have been done on different strains of fungi to determine which produce the highest germination rates for different orchid species. Seed embryo culture usually takes place in a lab, where seed is placed in a small, clear, covered container ontop a base containing nutrients and beneficial fungi. Though an orchid plant can produce thousands of seed, in nature only a few find appropriate conditions in which they can survive. However, using current seed embryo culture techniques usually produces a high germination success rate.
  • Asexual: Usually done when trying to preserve a speciman, such as in conservatories; not for mass propagation. Orchids can be asexually reproduced in a few ways. Division is done by separating pseudobulbs into sections with 2-3 nodes each. Occasionally, a bud will give rise to a young plant at the top, the side of a psuedobulb, or cane. Top cutting is done when a plant becomes leggy; new roots will develop readily. Monopodial orchids can be propagated by tip cuttings. Recently, some terrestrial hardy orchids have been propagated in vitro.


IV. Growing/Flowering

  • Light - (photosynthesis, photoperiodic responses): There are both sun-loving and partial shade orchids. Generally, most orchids prefer indirect or filtered light. The rule of thumb is to provide as much light as the leaves can take without burning, usually 50% shading. Orchid plants which receive enough light have short, plump stems with bright green leathery leaves. Those receiving too much sunlight are yellowish, stunted, and even scorched. Those under too much shade have darker green, soft and succulent leaves with thin, spindly stems.
  • Temperature (recommended/necessary for different growth stages or growth regulation): There are 3 temperature categories of orchids: Warm species prefer day temperatures up to 90°F and 65°F for a minimum night temperature. Intermediate species prefer 80°F days and 60°F nights. Cool species prefer 75°F days and 55°F nights. Most orchids, however, require a lower night temperature for both strong growth and often to initiate bloom.
  • Water: More orchids are killed by overwater rather than underwatering. Overwatering leads to root rot and many other diseases and pests (see Disorders). Water as media approaches dryness, preferrably in the mornings on sunny days. Clean water with a pH around 7 is best, but most orchids will tolerate a pH between 5 and 8.5. Watering with lower or higher pH or with high levels of dissolved minerals can prevent nutrient uptake. Orchids prefer high humidity, so it is helpful to mist regularly or use a fogger as long as there is good air circulation and ventilation.
  • Nutrition: Most species are light feeders, generally give 50-100 ppm nitrogen 3X weekly. Use higher levels in the spring during rapid growth or with Phalaenopsis species, which should be given 200 ppm N. Calcium, magnesium, and micronutrients are usually not added to standard fertilizer solutions. Fertigated plants should be flushed with pure water every fourth watering to prevent accumulation of nutrients. Use high phosphorus and potassium fertilizers before and during flowering.
  • Media/Potting/Planting: Usually no media is required, just support material. Most orchids are epiphytes, which are grown in fir or redwood bark, crumbled charcoal, pebbles, or on cork plaques. Other less common types of orchids are lithophytes, which grow naturally on rocks, terrestrials, which can be grown in a regular media such as ProMix or MetroMix or sand, and saprophytes, which are found growing in decaying vegetation in nature so they should be provided a media with high organic content. Media must be well drained with good circulation. Traditionally, orchids have been grown in terra cotta pots, which breathes better than plastic and sometimes has holes in the sides. However, terra cotta also has many disadvantages, so orchids are now more commonly produced in thin plastic pots. Open baskets of wood or cork mounts are also used.
  • Atmosphere
  • Growth Regulation (chemical, environmental, etc.)


V. Special Considerations - (special timing or growing techniques, idiosyncraces, etc.)


VI Disorders

  • Insect
  • Disease
  • Physiological


VII. Marketing and Grading

  • Areas of production in U.S.
  • Specific dates or holidays if applicable


VIII. Postharvest Handling


IX. Cultivars


X. References