ORCHID SPECIES CULTURE
Charles and Margaret Baker

Cymbidium erythrostylum Rolfe

AKA: Cyperorchis erythrostyla (Rolfe) Schlechter.

ORIGIN/HABITAT: Vietnam (Annam). Plants grow at about 4920 ft. (1500 m).

CLIMATE: Station #48881, Dalat, Vietnam, Lat. 11.1N, Long. 108.1E, at 3156
ft. (1035 m). Temperatures are calculated for an elevation of 4750 ft.
(1447 m), resulting in probable extremes of 88F (31C) and 38F (3C).

N/HEMISPHERE    JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
F AVG MAX        75   77   79   80   79   76   76   75   75   75   74   74
F AVG MIN        51   52   54   57   60   60   60   60   60   58   55   53
DIURNAL RANGE    24   25   25   23   19   16   16   15   15   17   19   21
RAIN/INCHES     0.2  0.9  1.6  4.6  9.1  6.1  7.7  8.2 10.1  9.7  2.7  1.3
HUMIDITY/%       68   64   65   71   78   81   82   83   84   82   76   73
BLOOM SEASON      *    *                                 **  ***  ***    *
DAYS CLR @ 7AM   13   13   13    9    5    3    2    2    2    5    7   10
DAYS CLR @ 1PM    8    8    8    2    0    0    0    0    0    1    3    4
RAIN/MM           5   23   41  117  231  155  196  208  257  246   69   33
C AVG MAX      23.7 24.9 26.0 26.5 26.0 24.3 24.3 23.7 23.7 23.7 23.2 23.2
C AVG MIN      10.4 11.0 12.1 13.7 15.4 15.4 15.4 15.4 15.4 14.3 12.6 11.5
DIURNAL RANGE  13.3 13.9 13.9 12.8 10.6  8.9  8.9  8.3  8.3  9.4 10.6 11.7
S/HEMISPHERE    JUL  AUG  SEP  OCT  NOV  DEC  JAN  FEB  MAR  APR  MAY  JUN

Cultural Recommendations:

LIGHT: 3000-4000 fc. In the habitat, light is lower in summer and early
autumn because it is reduced by the heavy clouds associated with the
summer monsoon. This seasonal variation should be duplicated in
cultivation by providing at least 50% shading during the middle of the day
in summer. Shading should be removed allowing as much light as possible,
short of burning the leaves, in autumn and winter.

TEMPERATURE: Summer days average 75-76F (24C), nights average near 60F
(15C), with a diurnal range of 15-16F (8-9C).

HUMIDITY: 75-85% for most of the year.

WATER: Rainfall is heavy from late spring through early autumn, with
short, one month transitions into and out of the 4 month winter dry
season.

FERTILIZER: A balanced fertilizer mixed at near recommended strength
should be applied weekly during periods of active growth. Many growers
recommend using a fertilizer lower in nitrogen and higher in phosphorus
during autumn to promote better blooming the next season and to allow the
new growths to harden before winter. In order to prevent salt buildup, the
medium should be leached every few weeks during periods of heavier
fertilizer applications. This is especially important in areas with
heavily mineralized water. Leaching is performed by watering the plant
normally to dissolve any accumulated salts, and then an hour or so later
running water equal to about twice the volume of the pot through the
medium.

REST PERIOD: Winter days average 74-77F (23-25C), nights average 51-53F
(10-12C), with an increased diurnal range of 21-25F (12-14C). Rainfall is
low for 4 months in winter and early spring, so water should be reduced
but not eliminated during this time. The high humidity and nightly cooling
result in frequent, heavy deposits of dew, and more water is available as
mist from fog and low clouds. These conditions may be simulated in
cultivation by occasional early morning misting, with a light watering
every 2-3 weeks, especially if a period of bright sunny weather is
expected. Fertilizer should be reduced or eliminated until active growth
resumes and watering is increased in the spring. Relatively high light
levels should be maintained to reflect the greater number of clear winter
days found in the habitat.

GROWING MEDIA: Plants should be kept moist during the growing season.
Consequently, the medium needs to retain some moisture, but it also needs
to be open and fast draining to prevent root rot which occurs in soggy,
stale medium. Most growers use a mix based on either fir bark or chopped
tree-fern fiber. Chopped sphagnum moss, osmunda, gritty sand, perlite,
charcoal, and fibrous loam are other materials that are frequently added
in varying amounts to the basic media. Some growers use straight small to
medium fir bark. Medium-grade bark in the bottom half of the pot, topped
with fine bark mixed with about 10% perlite and 10% charcoal produces very
good results. Cymbidiums are heavy feeders, and growers frequently
recommend adding old manure and other forms of solid fertilizer to the
media. Plants should be repotted every two years, or more often if the
plant outgrows the pot or if the media breaks down. Repotting should be
done when new root growth starts in late winter with plants that are not
carrying an inflorescence. Otherwise, repotting should be done as soon
after flowering as possible, with extra care taken not to break the
brittle new roots.

MISCELLANEOUS NOTES: The bloom period shown in the climate table is based
on cultivation records. In nature, plants bloom in late spring-early
summer. We wondered what might cause spring blooming in nature and fall
blooming in cultivation and after reviewing the climate data, we speculate
that plants might bloom in response to the wet/dry cycle. It is very
difficult to keep cultivated plants wet enough during hot summer days, so
it may be that they bloom in response to dryer conditions. Conditions
required to initiate blooming have not been identified. 

Plant and Flower Information:

PLANT SIZE AND TYPE: An 18-20 in (45-50 cm) epiphyte, lithophyte, or
terrestrial.

PSEUDOBULBS: 2.4 in. (6 cm) tall. Each flattened oval shaped pseudobulb is
covered by the bases of the leaves and 2-3 cataphylls or lower leaves that
emerge from the base. 

LEAVES: 18 in. (45 cm) long. Each growth carries 6-8 narrow, arching,
distichous leaves 

INFLORESCENCE: 6-14 in (15-35 cm) long. The slender, arching peduncle
emerges from the base of immature pseudobulbs between the cataphylls or
lower leaves. 

FLOWERS: 4-8 per inflorescence. Each blossom is about 1.2 in. (6 cm)
across. The appear triangular with broad, flat sepals that open fully, and
petals that point forward and cover the column and the base of the lip.
Sepals and petals are white with a texture that glistens as though they
have been frosted. The lower end of the petals, which are pale pink along
the mid-vein, are sometimes spotted with pink at the base. The lip is
yellow-white, with darker yellow on the midlobe. It has strong deep red
veins become broken and spotted near the edges of the sidelobes. The
flowers are not fragrant, but they are very long lasting.

HYBRIDIZING NOTES: Chromosome count is 2n = 40. This species has been
widely used in hybridization because it has large, long lasting flowers
and an early bloom season. Growers report that, when crossed with C.
mastersii, the offspring often bloom 2-3 years from the same pseudobulb.

REFERENCES: 

Crossley, J. 1991. Cymbidiums in California or my forty year love affair
with cymbidiums. Orchid Digest, 55(1):34, Jan.-Mar.

Du Puy, D., and P. Cribb. 1988. The genus Cymbidium. Timber Press,
Portland, OR.

Hamilton, R. 1990. Flowering months of orchid species under cultivation.
Orchid Biology Reviews and Perspectives, V. J. Arditti, ed. Timber Press,
Portland, Or. 

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


Copyright 1997, Charles O. Baker and Margaret L. Baker
Sheet version 4060121

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