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).
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
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.
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 2 in. (5 cm) to 4 in. (10 cm), depending on the species or hybrid, 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.