Cattleyas |
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Cattleyas grow quite easily in our climate and are very rewarding
with their spectacular brightly coloured blooms. They can be grown under
a range of conditions. The following notes are a guide how to grow
cattleyas.
LIGHT-SHADING
Cattleyas require less light than cymbidiums, about 70% to 80% shade.
They will grow under brighter conditions if the plant is acclimatised to
it slowly. They grow best in a glasshouse with 70% to 80% shading but
will still perform well under fibreglass sheeting.
TEMPERATURE
Cattleyas can be grown successfully cold, without any form of heating
and will still flower well. If given heat during the winter (a minimum
temp of about 12°C) they will continue to grow without a rest and small
plants will mature more quickly. Flowering size plants may flower twice
a year with heat. Cattleyas need to be protected from frosts and
therefore in winter should be grown under fibreglass, glass or other
protective material. The protective covering will also prevent over
watering from winter rains. All orchids prefer air movement, the more
the better.
POTTING MEDIOM
In nature, cattleyas grow on tree limbs and forks of limbs so they
require a very open mix. Make sure the potting mix used is very open.
The roots act like a sponge and will hold water. If the potting medium
is constantly wet, the roots of the Cattleya will rot and the plant may
be lost. We use weathered pine b~rk. The pine bark size is larger than
that used for cymbidiums, approximately 1 0-20mm chunks. I do not add
lime to the pine bark but let nature weather it. It takes about 6 months
to weather the bark. During this time it is kept constantly moist. If
not weathered, toxic substances will be released, nitrogen will be
robbed from the plant to break the bark down and the plant will dry out
excessively due to the new bark not holding the moisture.
WATERING
Rate of watering depends on numerous factors, climate, potting medium,
size of the plant and where they are grown. If the potting mix used is
of a very open nature then it is hard to over water your orchid. We grow
cattleyas under fibreglass and in a glasshouse. We try to provide as
much air movement as possible so they dry out very quickly after
watering. In summer we water once a day in the morning using over-head
sprinklers. In autumn and spring about every second day and in
mid-winter about every third day depending on the weather. In winter, if
very wet and humidity is high the watering can be delayed for 4 to 7
days. We do not dry out our plants to the extreme that the bulbs shrink.
FERTILIZING
Cattleyas obtain nutrients in nature from bird droppings and broken down
leaf matter that falls around it. We do not believe in the use of a lot
of fertilizers. We add slow release fertilizer to our potting medium at
the rate of one tablespoon to a 200mm pot (8" pot). The slow release
fertilizers we use are Nutricote (3-4 month release) and Magamp. The
slow release fertilizers are mixed into the pine before potting.
RE-POTTING
Large Cattleya plants will still grow and flower well when the new
growth has reached the edge of the pot and its roots are outside. For
best appearance these plants should be either repotted or divided. It is
best to repot or divide in spring. Cattleyas should be repotted into new
mix at least every two to three years otherwise the root system will
start to deteriorate. Small plants will require potting at a more
frequent interval until they reach a 150mm size pot. They are best grown
in a plastic squat pot with extra drainage holes cut in the bottom.
DIVDING
I like to grow my cattleyas into large specimen size plants. When
dividing cattleyas, three or more green growths should be in a division.
Cut through the rhizome with a sterilized knife where the plant is to be
divided and place a small object (such as a match) to keep the cut
apart. After a few months the old division or backcut will develop a new
growth. At this stage repot each piece.
PESTS AND DISEASES
The biggest problem is fungi (black rot). The best preventative is good
air movement or ventilation. In autumn and spring it is best to apply a
fungicide such as Fongarid. If a leaf develops black rot, cut the
diseased area out and soak the plant in Fongarid for 15 minutes. Other
pests such as scale, mealy bug, thrips must also be watched out for.
FLOWERING
Don't open the sheaths if possible. Let the buds break through on their
own. If the sheath goes yellow then tear a small hole in the base so
excess water drains out. If torn open at the top, water will collect in
the sheath and rot the buds. Once the buds are exposed watch for pests
and put snail pellets around. There are two main flowering seasons,
spring and autumn. With good culture a plant may flower twice a year.
Flowers normally last one to two months and can be strongly perfumed.