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ORCHID SPECIES CULTURE Charles and Margaret Baker Zygopetalum mackayi Hooker AKA: N/A. ORIGIN/HABITAT: Southern Brazil from the states of Minas Gerais and Espirito Santo in the north to Rio Grande do Sul in the south. Plants grow as terrestrials in sparse woods, on brushy gentle slopes, or on grassy plains or meadows near forests at 4250-5600 ft. (1300-1700 m). CLIMATE: Station #83781, Sao Paulo, Brazil, Lat. 23.6S, Long. 46.7W, at 2628 ft. (801 m). Temperatures are calculated for an elevation of 4500 ft. (1370 m), resulting in probable extremes of 94F (34C) and 26F (-3C). N/HEMISPHERE JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC F AVG MAX 60 61 61 62 66 69 71 73 70 67 62 60 F AVG MIN 47 47 49 51 53 56 57 58 56 53 48 48 DIURNAL RANGE 13 14 12 11 13 13 14 15 14 14 14 12 RAIN/INCHES 1.5 2.1 3.5 4.6 6.0 9.4 8.8 7.8 6.1 2.3 3.0 2.4 HUMIDITY/% 75 73 77 78 80 80 82 83 81 82 80 79 BLOOM SEASON ** ** ** * * * * ** *** *** DAYS CLR @ 9AM 5 7 3 4 4 5 3 1 2 2 1 2 DAYS CLR @ 3PM N/A RAIN/MM 38 53 89 117 152 239 224 198 155 58 76 61 C AVG MAX 15.6 16.1 16.1 16.7 18.9 20.7 21.7 22.8 21.1 19.4 16.7 15.6 C AVG MIN 8.3 8.2 9.3 10.5 11.6 13.2 13.8 14.3 13.2 11.6 8.8 8.8 DIURNAL RANGE 7.3 7.9 6.8 6.2 7.3 7.5 7.9 8.5 7.9 7.8 7.9 6.8 S/HEMISPHERE JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN Cultural Recommendations: LIGHT: 2000-3000 fc. Relatively bright light is required by most Zygopetalums, and healthy plants that do not bloom usually have inadequate light. At proper light levels, the leaves should be light green. A yellowish cast to the leaves indicates too much light while soft, weak, dark green leaves indicate too little. Many growers successfully grow zygopetalums under the same conditions and as companions of cymbidiums. TEMPERATURES: Summer days average 69-73F (21-23C), and nights average 56-58F (13-14C), with a diurnal range of 13-15F (8-9C). Growers report that these plants will tolerate much warmer temperatures for short periods without adverse effects. HUMIDITY: Near 80% for most of the year, dropping to near 75% in winter and early spring. WATER: Rainfall is moderate to heavy from spring to early autumn, but conditions are somewhat drier in late autumn and winter. Cultivated plants should be kept evenly moist while actively growing, but water should be gradually reduced in autumn. Plants should not be allowed to dry out completely, however. FERTILIZER: A balanced fertilizer, mixed at 1/4-1/2 recommended strength, should be applied weekly during periods of active growth. Many growers use a fertilizer with lower nitrogen and higher phosphate in autumn. This improves blooming the next season and encourages new growths to harden before winter. Pots should be leached every few weeks to prevent salt buildup, especially when fertilizer is being applied most heavily. Plants should first be watered normally to dissolve any accumulated salts. An hour or so later, the medium is flushed with water equal to about twice the volume of the pot. Year-round leaching is important in areas with heavily mineralized water. REST PERIOD: Winter days average 60-61F (16C), and nights average 47-49F (8-9C), with a diurnal range of 12-14F (7-8C). Growers report that these plants will tolerate temperatures near freezing for short periods, but it is better if they are not exposed to such extremes. While rainfall is lower in winter, some is received each month. Also, additional moisture is available from heavy dews, which are common. Therefore, water should be reduced for cultivated plants so that they become somewhat dry between waterings, but they should not be allowed to dry out completely. Fertilizer should be reduced or eliminated until water is increased in spring. GROWING MEDIA: Plants are usually grown in pots filled with a relatively coarse, well drained medium. Most growers use either fir bark or a mixture of bark and moisture retaining additives. Rose (1993) recommended a mix made up of equal parts of fine and medium fir bark with about 10% large-grade perlite added. Because plants have rather large and extensive roots, relatively large deep pots are normally used. Repotting should be done just as new root growth is starting, often when new growths are about half completed, or as soon after flowering as possible. MISCELLANEOUS NOTES: The bloom season shown in the climate table is based on cultivation reports. Zygopetalum mackayi is often confused with the much more common Zygopetalum intermedium, and plants in many collections are mislabeled. The most easily apparent differences are that in Zygopetalum mackayi the petals are considerably shorter than the sepals instead of being about the same length, the inner part of the lip is only slightly roughened instead of noticeably fuzzy, and the underside of the column is smooth instead of fuzzy. Plant and Flower Information: PLANT SIZE AND TYPE: A moderate to large sympodial terrestrial plant 14-23 in. (36-58 cm) tall. PSEUDOBULBS: 2-3 in. (5-8 cm) tall and 1-2 in. (3-5 cm) in diameter. They are bright green and smooth when young but become yellow-green and very wrinkled with longitudinal furrows when older. The young pseudobulbs are protected by 2 or more leaf-like sheathing bracts which grow from the base, but these bracts become dry and fibrous with age. LEAVES: 2-3 leathery, strap-like, bright-green leaves with prominent veins grow from the top of the pseudobulb. They are 12-20 in. (30-50 cm) long, about 2 in. (5 cm) wide, and have long tapering tips. INFLORESCENCE: 1 strong, erect spike that may be up to 39 in. (100 cm) long emerges from the sheathing bracts at the base of the new growth. FLOWERS: 5-10 blossoms near 3 in. (8 cm) across are evenly spaced along the inflorescence and often open simultaneously. The waxy flowers are long lasting and are very fragrant. The sepals and petals often curve inward slightly but usually recurve at the tips. They are yellowish-green with large irregular blotches of reddish-brown or maroon. The large, flat opening lip is white with dark red to almost blue veins radiating from the base. These veins may have small hairs, which are the same color as the vein, along their length; but these hairs are almost absent on some plants. HYBRIDIZING NOTES: N/A REFERENCES: Associação orquidofila de São Paulo. 1977. Native orchids of Brasil. Associação orquidofila de São Paulo. Hawkes, A.  1987. Encyclopaedia of cultivated orchids. Faber and Faber, London. McQueen, J., and B. McQueen. 1993. Orchids of Brazil. Timber Press, Portland, OR. Pridgeon, A. ed. 1992. The illistrated encyclopedia of orchids. Timber Press, Portland, OR. Rentoul, J. 1985. Growing orchids. book 2. Cattleyas and other epiphytes. Timber Press, Portland, OR. Rose, J. 1993. Orchid care - Zygopetalum. American Orchid Society Bulletin 62(7):733-734. Veitch, J., and Sons. [1887-1894] 1963, 1981. Manual of orchidaceous plants, vols. I-II. James Veitch and Sons, Royal Exotic Nursery, Chelsea, London. Reprint, vol. I, A. Asher and Co., Amsterdam, The Netherlands; reprint, vol. II, Bishen Singh Mahendra Pal Singh, Dehra Dun, India. PHOTOS/DRAWINGS: . Copyright 1997, Charles O. Baker and Margaret L. Baker Sheet version 13936072 ......................................................................... Please remember that this sheet is for your use only, and though it was provided free of charge, it may not be reproduced or retransmitted in any way without permission. ......................................................................... __________________________________________________________________________ "Orchid Species Culture" Charles & Margaret Baker, Portland, Oregon USA Orchid Culture & Pollination site http://www.orchidculture.com email <firstname.lastname@example.org> __________________________________________________________________________ "Orchid Species Culture Vol. 1 - Pescatorea, Phaius, Phalaenopsis, Pholidota, Phragmipedium, Pleione" 250 pages of culture information. "Orchid Species Culture Vol. 2 - Dendrobium" 850 pages of culture information for more than 1230 Dendrobium species. "The genus Paphiopedilum--Natural History and Cultivation" - Part 1 Dr. Guido Braem, Charles and Margaret Baker ISBN 0-9665337-0-4 Full page color photograph of each species. "The genus Paphiopedilum--Natural History and Cultivation" - Part 2 Dr. Guido Braem, Charles and Margaret Baker ISBN 0-9665337-1-2 Full page color photograph of each species. "Orchid Species Culture Vol. 3 - The Laelia/Cattleya Alliance" coming in a few months. __________________________________________________________________________