Cattleyas are
among the most popular orchids. Their culture is
often used as the basis for comparison with other
types of orchids. Cattleyas and their related
hybrids come in many colors, shapes, forms and
sizes. Culture varies only slightly among most of
these. This sheet is a general guide to basic
cattleya culture. Like many other cultivated
orchids, cattleyas are epiphytes, or air plants.
They have developed water-storage organs, called
pseudobulbs, and have large, fleshy roots covered
with a spongy, water-retentive velamen. They are
accustomed to being dry at the roots between
waterings, and therefore should be potted in
free-draining media.
L I G H T is the
most important factor in growing and flowering
cattleyas, whether in a greenhouse or in the
home. Bright light to some sun should be given to
the plants, with no direct sun in the middle of
the day. This means an east, shaded-south (as
with a sheer curtain) or west window in the home,
and 50 to 70 percent full sun in a greenhouse
(3,000 to 5,000 foot-candles). Leaves should be a
medium-green color, pseudobulbs erect and
requiring no staking.
TEMPERATURES should
be 55 to 60 F at night and 70 to 85 F during the
day. Seedlings should have night temperatures
five to 10 degrees higher. A 15- to 20-degree
differential between day and night is
recommended, especially for mature plants. Higher
day temperatures can be tolerated (up to 95 F),
if humidity, air circulation and shading are
increased.
W A T E R should
be provided in two ways: in the pot by watering
and in the air as humidity. Watering in the
container is dictated by many criteria: size and
type of the vessel, temperature, light, etc.
Mature cattleyas need to dry out thoroughly
before being watered again. Seedlings need more ~
constant moisture. Compare the weight of a dry
pot of the same size and type of mix; it can
indicate if a plant needs water by the relative
weight -- light means dry, heavy means wet. If in
doubt, it's best to wait a day or two until
watering. Plants in active growth need more water
than plants that are resting. Water below 50 F
may injure plants, as will water softened by the
addition of salts.
H U M I D I T Y should
be 50 to 80 percent for cattleyas. This can be
provided in the home by placing the plants on
trays of gravel, only partially filled with water
so that the plants do not sit in the water. Air
should always be moving around the plants to
prevent fungal or bacterial disease, especially
if high humidity or cool temperatures exist. In
the greenhouse, the humidity is best increased by
use of a humidifier. Evaporative cooling
increases humidity while cooling the air.
FERTILIZE on a
regular schedule. In fir bark, a high-nitrogen
(such as 30-1010) formulation, or a similar
proportion, is used. Otherwise, use a balanced
fertilizer When in active growth, plants need
fertilizer at least every two weeks, and when not
actively growing, once a month. Fertilizer can
also be applied with every watering at
one-quarter the recommended dilution. Thorough
flushing with clear water every month is
recommended to prevent the buildup of fertilizer
salts.
P O T T I N G is
necessary when the rhizome of the plants
protrudes over the edge of the pot or the potting
medium starts to break down and drain poorly
(usually after two to three years). It is best to
repot just before new roots sprout from the
rhizome, after flowering or in the spring.
Mature cattleyas are usually potted in
coarser potting material than are seedlings.
Until a plant has at least six mature
pseudobulbs, it generally should be put into a
larger pot and not divided. If dividing a plant,
three to five pseudobulbs per division are
required. Select a pot that will allow for
approximately two years of growth before crowding
the pot. Pile mix against one side of the pot and
cut off any dead roots. Spread the firm, live
roots over the pile, with the cut rhizome against
the side of the pot. Fill the pot with medium,
working it around the roots. Pack firmly and
stake if necessary. Keep the plant humid, shaded
and dry at the roots until new root growth is
seen.
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