ORCHID SPECIES CULTURE
Charles and Margaret Baker

Laelia tenebrosa (Gower) Rolfe

AKA: Laelia grandis var. tenebrosa Gower. 

ORIGIN/HABITAT: Brazil. The habitat is generally thought to extend from
southern Bahia to northern Espírito Santo. Miranda (1990), however,
reported that the habitat is limited to a very small area in southern
Espírito Santo where plants grow on large trees in dense forest. He
further stated that this limited habitat has been totally destroyed and
that this species, which has always been rather rare, is now impossible to
find in nature. 
Even with all that has been written about this large, showy species, few
details of habitat location and elevation are available. Therefore, the
habitat location and elevation is estimated based on the habitats of other
species known to grow in the same habitat and to hybridize naturally with
Laelia tenebrosa. However, growers should use the resulting Cultural
Recommendations with caution. 

CLIMATE: Station #83648, Vitória, Brazil, Lat. 20.3S, Long. 40.3W, at 13
ft. (4 m). Temperatures are calculated for an estimated elevation of 1500
ft. (460 m), resulting in possible extremes of 97F (36C) and 38F (3C). 

N/HEMISPHERE    JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
F AVG MAX        72   73   73   75   76   79   81   82   81   78   76   74
F AVG MIN        60   60   62   64   65   67   68   68   68   66   63   61
DIURNAL RANGE    12   13   11   11   11   12   13   14   13   12   13   13
RAIN/INCHES     2.2  2.1  2.7  4.2  5.7  6.3  3.7  3.0  5.2  3.9  2.3  3.4
HUMIDITY/%       83   84   86   84   86   85   82   83   84   85   82   84
BLOOM SEASON           *    *    *   **  ***   **    *    *    *    *    *
DAYS CLR @ 9AM   10   12    6    3    2    2    6    6    7    8   12   13
RAIN/MM          56   53   69  107  145  160   94   76  132   99   58   86
C AVG MAX      22.2 22.8 22.8 23.9 24.4 26.3 27.3 27.8 27.2 25.6 24.4 23.3
C AVG MIN      15.6 15.6 16.7 17.8 18.4 19.5 20.1 20.1 20.1 18.9 17.3 16.2
DIURNAL RANGE   6.6  7.2  6.1  6.1  6.0  6.8  7.2  7.7  7.1  6.7  7.1  7.1
S/HEMISPHERE    JUL  AUG  SEP  OCT  NOV  DEC  JAN  FEB  MAR  APR  MAY  JUN

Cultural Recommendations: 

LIGHT: 3500-4000 fc. Some growers report that bright light is essential to
initiate blooms, but full sun should be avoided. Others, however, report
successful flowering with about 2500 fc of light. If plants do not bloom
because brighter conditions are needed, light should be increased
gradually to allow the plant time to adapt. Strong air movement should be
provided at all times.

TEMPERATURES: Summer days average 79-82F (26-28C), and nights average
67-68F (20C), with a diurnal range of 12-14F (7-8C). Growers report that
plants are healthy when temperatures drop to 60F (16C) or increase to 100F
(38C) for short periods. Note however, that these high temperatures are
outside the normal extremes estimated for the habitat. Water should be
reduced if temperatures are cool and increased anytime temperatures are
hot. 

HUMIDITY: Near 85% year-round. 

WATER: Rainfall is moderate to heavy most of the year with somewhat drier
conditions for about 3 months in winter, but average rainfall may be
somewhat greater in the higher elevation habitat. Cultivated plants should
be watered heavily while actively growing, but the roots must always dry
rapidly after watering. Water should be reduced somewhat after new growths
mature in autumn. 

FERTILIZER: 1/4-1/2 recommended strength, applied weekly while plants are
actively growing. A high-nitrogen fertilizer is beneficial from spring to
midsummer, but a fertilizer high in phosphates may be used in late summer
and autumn. 

REST PERIOD: Winter days average 72-74F (22-23C), and nights average
60-61F (16C), with a diurnal range of 12-13F (7C). Rainfall in the habitat
is somewhat lower in winter, but the high humidity indicates that some
additional moisture is generally available from mist and heavy dew.
Cultivated plants need less water in winter, particularly if grown in the
dark, short-day conditions common in temperate latitudes. Plants should
never dry out completely, however. Fertilizer should be reduced or
eliminated until heavier watering is resumed in spring. 

GROWING MEDIA: Small pots or baskets may be filled with a very coarse,
open, fast-draining medium that allows the roots to dry rapidly after
watering. Undersized pots with room for only 1-2 years' growth are
recommended because the medium in larger pots remains wet for too long
after watering. If the roots do not dry quickly, they eventually die from
root rot. Most growers recommend using coarse-sized fir bark in either
clay or plastic pots, but others prefer clay pellets from concrete
manufacturers in clay pots. Plants also grow well mounted on tree-fern or
cork slabs, but humidity must be high and plants need at least daily
watering in summer. Mounted plants may need several waterings a day during
extremely hot, dry weather. Repotting or dividing should be done only when
new root growth is just starting. 

MISCELLANEOUS NOTES: The bloom season shown in the climate table is based
on cultivation records. In nature, plants bloom in early summer. 
Although this species is rare if not extinct in nature, plants are still
readily available for cultivation as the better forms are now widely grown
from seed-propagated populations. 
Growers consider this a difficult plant to grow successfully, so careful
attention should be given its cultural requirements.

Plant and Flower Information:

PLANT SIZE AND TYPE: An 18 in. (46 cm) sympodial epiphyte. 

PSEUDOBULB: To 7 in. (18 cm) long by about 1.2 in. (3 cm) wide. The
club-shaped pseudobulbs are covered with sheaths that become dry and
papery with age. The robust plants sometimes have a purplish brown tint on
the pseudobulbs and leaves. Some growers indicate that plants seldom
become large since an old growth tends to die as a new lead growth
develops, and plants almost never break multiple leads. 

LEAVES: About 11 in. (28 cm) long by 2.4 in. (6 cm) wide. The leaves of
cultivated plants may reach a length of 15 in. (38 cm). A single erect,
leathery leaf is carried at the top of each pseudobulb. Leaves range from
oblong to egg-shaped to straplike and are rounded at the tip.

INFLORESCENCE: 12 in. (30 cm) long. An erect flower spike emerges through
a wide, flat sheath at the top of the most recently matured pseudobulb. 

FLOWERS: 2-3. The large, showy, fragrant blossoms are frequently 7 in. (18
cm) across. They usually last about 2 weeks. The narrow, bronze or coppery
sepals and petals, which sometimes are twisted slightly, are usually
almost flat with slightly wavy margins, especially on the petals. The
3-lobed lip has large sidelobes that roll upward to form a tube around the
column. The resulting large, trumpet-shaped lip has a deep purple ring at
the base of the flaring midlobe with a lighter colored margin toward the
ruffled, reflexed apex. The throat is yellow with prominent veins that
extend over the disc to the margin of the lip. Several color variations
are known in cultivation, including an alba form with green sepals and
petals and a white lip. The very old cultivar 'Walton Grange' has
nankeen-yellow sepals and petals and a white lip decorated with purple
markings. 

HYBRIDIZING NOTES: N/A. 

REFERENCES: 

Bechtel, H., P. Cribb, and E. Launert. 1980. Manual of cultivated orchid
species. MIT Press, Cambridge, Mass.

Hamilton, R. 1988. When does it flower? 2nd ed. Robert M. Hamilton, 9211
Beckwith Road, Richmond, B.C., Canada V6X 1V7.

Hamilton, R. Orchid Nurse. 

Hawkes, A. [1965] 1987. Encyclopaedia of cultivated orchids. Faber and
Faber, London. 

Miranda, F. E. 1990. Brazilian laelias - Part I: Section Cattleyodes.
American Orchid Society Bulletin, 59(3): 234-245. 

Withner, C. 1990. The cattleyas and their relatives, vol. II:the laelias.
Timber Press, Portland, OR. 

PHOTOS/DRAWINGS: 

Bechtel, H., P. Cribb, and E. Launert. 1980. Manual of cultivated orchid
species. MIT Press, Cambridge, Mass.

Miranda, F. E. 1990. Brazilian laelias - Part I: Section Cattleyodes.
American Orchid Society Bulletin, 59(3): 234-245. 

Withner, C. 1990. The cattleyas and their relatives, vol. II:the laelias.
Timber Press, Portland, OR. 


Copyright 1997, Charles O. Baker and Margaret L. Baker
Sheet version 25626971

.........................................................................
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.
.........................................................................

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 "Orchid Species Culture" Charles & Margaret Baker, Portland, Oregon USA

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