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 - Temperature - there are two distinct phases of phalaenopsis growing: the vegetative phase and the flowering phase.

Vegetative phase - To maintain vegetative orchid plants, they must be grown at 82°F (28°C) or higher to avoid the development of immature inflorescences (spiking). This high temperature also promotes rapid leaf growth. Flowering can be suppressed with a cooler night (77°F or 25°C) if the day temperature is sufficiently warm (82°F or 30°C). If young orchid plants (for example, plants with a leaf span of less than 10 inches or 25 centimeters) are exposed to lower temperatures, especially during the day, then premature spiking can occur.

Spikes that develop on young orchid plants are often not uniform and spikes are of poor quality (for example, short flower spikes with a low flower count). The small-flowered multiflora "mini phalaenopsis" do flower uniformly on plants with a leaf span of less than 8 inches (20 centimeters).

Epiphytic orchids as Phalaenopsis and most other orchids are ok with temperatures around 90°F to 95°F (32°C to 35°C) for a couple of hours per day if there is adequate moisture around and enough air movement.

Because phalaenopsis orchids and many other orchids are tropical plants, their growing cycle needs orchid care, they should not be exposed to temperatures below 50°F (10°C) or large and rapid fluctuations in temperature, as they will suffer from cold injury.

A common symptom of orchid cold damage is the development of yellow, water-soaked and sometimes sunken spots on upper leaf surfaces. Chilling injury can develop in a matter of a few hours exposure to low temperatures.

After four to five weeks at these temperatures, orchid rower plants can be grown at a wider range of temperatures (63°F to 79°F, or 17°C to 26°C) to time flowering with a specific marketing date. The flower spike usually emerges from the third and sometimes the second or fourth node below the uppermost mature leaf (Figure 3).

Some orchid growers in warm climates use air-conditioned greenhouses to induce phalaenopsis into flower during the warm months for year-round production, because naturally low temperatures do not exist during the summer.

Orchid flower bud initiation starts after the spike has reached about 2 inches (5 centimeters) in length if environmental conditions are favorable. Time from spike initiation to the first flower opening depends on the average daily temperature and the grow orchid hybrid. For example, time from spike emergence to open flower in phalaenopsis 'Miva Smartissimo' at 68°F (20°C) and 73°F (23°C) occurred after 89 and 72 days, respectively.

Light - Light intensity for growing should be controlled throughout the phalaenopsis orchid production cycle. This requires shading during most of the year, except possibly during the winter in northern climates. Except in northern latitudes (such as in northern Europe), supplemental lighting is not necessary for growing phalaenopsis orchids. Photoperiod has no effect on flowering of most large- to medium-flowered phalaenopsis hybrids, although for some smaller-flowered hybrids, flowering may occur slightly earlier under short days.

Growing Orchids

When new roots begin to form during and leaves have regained their turgidity, light may be increased up to 1,500 foot candles during the remaining vegetative phase. Light above 1,500 foot candles can cause irreversible sun scald. During the orchid flowering phase, between 1,000 and 1,500 foot candles of light is recommended. Plants may tolerate up to 2,000 foot-candles if the temperature is not too high. As you can see in the orchid picture and photo.

Research has shown that spiking of phalaenopsis orchids can be prevented by low light (40 footcandles) or complete darkness. Most commercial growers inhibit flowering by providing high temperatures (82°F or 28°C or higher), but growers without temperature control (such 

Height Control - Growing of phalaenopsis usually does not require any means of height control. If height control is desired to shorten the portion of the inflorescence below the first flower, a single foliar application of Sumagic or Bonzi can be effective.

The plant growth regulator (PGR) application should be made before the spike has reached 2 inches (5 centimeters) in length for best results.

Alternatively, a quick orchid replanting root dip of mature plants in Sumagic (25 ppm) or Bonzi (100 ppm) can also effective. Plants treated with PGRs produce smaller leaves and subsequent flowering could be delayed. Late PGR sprays can cause flowers to be bunched together, creating an undesirable appearance. As with all PGRs, conduct your own trials on a small scale orchid garden or nursery, first to determine the appropriate rates.

Disease and Insects - Phalaenopsis orchids are susceptible to a variety of diseases and insects. To minimize the threat of infection and the spread of disease, benches, pots and cutting tools should be sanitized. In addition, orchid pots should be free of insects and pathogens. Diseased or infested plants should be discarded immediately and samples should be sent in for proper diagnosis. Orchid Plants can be particularly susceptible to pathogens soon after transplant, and thus moderating air movement and avoiding a constant wet medium after transplant are important.

Erwinia (bacterial soft rot) and pseudomonas (brown rot) are more prevalent during moist and warm conditions. The best way to avoid these rots is to water plants early in the morning so they are dry at night. Fungal diseases such as fusarium, rhizoctonia, pythium and phytophthora can also be problematic when cultural conditions are substandard. When conditions are cool and humid, Botrytis petal blight can develop quickly as small brown spots on flower buds and flowers.

Mealy bugs, spider mites, scales, slugs and snails can also be problematic on phalaenopsis orchids. Routine scouting for these pests should be made, and control measures should be taken rapidly to help prevent insect spread. About the authors: Roberto "RoLo" Lopez and Matthew Blanchard are graduate students and Erik Runkle is assistant professor and floriculture extension specialist at Michigan State University. Yin-Tung Wang is professor of floriculture at Texas A&M University. The authors thank the Fred C. Gloeckner Foundation, Project GREEEN and private greenhouse companies that support orchid research. Copyright Meister Media Worldwide. Provided by ProQuest Information and Learning Company. All rights Reserved.