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By slipperfreak at 2007-07-17 17:59
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Genus Description: Phragmipedium is a genus of slipper orchids native to tropical Central and South America. Like all slipper orchid genera, its species are highly variable; some have sprays of several flowers open at the same time with long, drooping petals while others have more rounded flowers that open sequentially. Most are large, vigorous plants with fans of sword-shaped leaves. These plants are typically rainforest dwellers (terrestrials) that receive a lot of mositure, but some are lithophytes (grow on rocks) or sometimes epiphytes (grow on trees) that receive less moisture. For this reason the genus can be divided into two: the mositure-loving species (Phrag. besseae group) and the dryer growing species (Phrag. caudatum group). Light: Most Phrags like bright light, and some (such as Phrag. caudatum) like very bright light (as for Cattleyas). Some species, like Phrag. besseae and Phrag. schlimii, like lower light (as for most mottled-leaved Paphs). The leaves should be a bright green color; dark green leaves indicate too little light while yellowish leaves indicate too much. Direct afternoon sunlight will scorch the leaves and flowers. Temperature: Phrags are intermediate growers. Most species like temps of around 20-25C during the day and around 5-6C lower at night for proper growth and flower formation. Most will tolerate temps 30-32C with more humidity and air movement. However, Phrags will develop larger, more colorful flowers in cooler temps. As well, a soft, brown bacterial rot can be a problem with Phrags during the summer. The risk of getting this is greater in higher temps. To treat, pull off any infected leaves and treat with Phyton-27 or cinnamon. The species Phrag. besseae is sensitive to high temps and will suffer in temps much higher than 25C, especially without plenty of humidity and air movement. Watering: Phrags like their water, and it is pretty hard to overwater them. Especially with the wet-growing besseae group, you can grow them in a tray of water and never have any problems; think wet. The drier growing caudatum group does better with less moisture, and in fact the species caudatum itself can dry out almost completely between waterings without any problems. Grow caudatum types as for Paphs - constant moisture but not wet. Another important thing to remember is water quality - use only pure water such as distilled, rain or reverse osmosis water as Phrags are sensitive to mineral and chemical buildup. Some Phrags are more tolerant of tap water as long as the pH is 7.5 or lower, such as Phrag. caudatum and Phrag fischeri (which actually likes lime); however Phrag. besseae and Phrag. boisserianum should have pure water to do best. Humidity & Air Movement: Phrags prefer fairly high humidity from 60-70%, coupled with plenty of air movement, especially during the summer. Many members of the caudatum group can tolerate low humidity down to 35% as long as nighttime humidity is high. Fertilizing: Phrags are sensitive to mineral and chemical buildup, but they still need nutrients to grow and flower properly. Generally, fertilizing at 1/8 strength every other watering, and flushing the mix out very well with clear water in between, is a good practice. You have to be especially careful with species like besseae, schlimii and boisserianum that are more sensitive to mineral buildup; their leaves will brown at the tips. With these, keep wet and flush often! When using pure water for irrigation, add 10% tap water to your fertilizer mix to supplement calcium and magnesium, unless your fertilizer contains these two crucial minerals. Repotting and Dividing: Phrags should be repotted at least every year, and those in the wet-growing group that are grown in bark mixes should be repotted every 6 months for best results as the bark decomposes rapidly. Phrags growing in rockwool are best repotted every 2 years. Note that rockwool builds up minerals very quickly and needs special attention to be paid when it comes to fertilizer and water quality. Phrags are vigorous growers and once they reach a certain age will develop multiple growths every year; these will need frequent repotting simply because they outgrow their pot. Use a free-draining mix; I recommend a fine grade bark mix for the more compact species like besseae and schlimii and a medium to coarse grade mix for the larger growers like longifolium and caudatum; this depends on the size of pot (coarse for larger pots). Add materials like chopped long-fiber sphagnum moss, clay pellets, charcoal and perlite/sponge rock to the mix. Many Phrags also grow well in PrimeAgra. When repotting, remove any dead roots (soft, mushy and hollow) and choose a pot in which the roots fit snuggly, and there is room for a few new growths. Dividing becomes necessary with mature plants as they are very vigorous and can get huge quickly. Simply use a sharp, sterilized knife to cut at the rhizome. A division should have at least one mature growth and a preferably a new lead, with plenty of healthy roots. Repotting and dividing are best done just after flowering. Additional Notes: The species Mexipedium xerophyticum is sometimes called Phragmipedium xerophyticum. It is very similar to a Phrag but is much smaller. This is a lithophyte from Mexico that likes very bright light, a free draining mix and careful watering (dry out quite a bit in between). It should be grown in wide shallow pans to accommodate its stoloniferous growth habit. It can also tolerate some lime. |
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