Also known as the boat orchid,
Cymbidium (sim-BID-ee-um) hybrids descend from species originating mainly
in the Himalayas, the mountainous regions of India and China. They can also be
found throughout the Far East: through Japan, Philippines and Australia.
Cymbidium orchids are large
evergreen plants; they have “strappey”, grass-like leaves shooting from
pseudo-bulbs at the base of the plant. They are clump-forming and have fleshy
roots.
Cymbidiums are usually grown in
conservatories or cool greenhouses. Different varieties flower between
September and April. There
are two main types of Cymbidium, standard and miniature. Standard Cymbidium –
differentiated from miniature cymbidium by the size of the pseudo-bulbs and
flowers – prefer cooler conditions to miniatures.
Flower spikes are produced in
autumn or winter from the newest pseudo-bulbs. Initially they look like leaf
growths but the flower spikes tend to be rounder at the tip and more fingerlike
than leaf growths. A flower spike may carry 1 to 30 blooms depending on the
variety
Temperature:
When in flower, Cymbidium like cool house temperatures of between 15-20°C.
The warmer they are kept, the shorter the flowers will last.
In summer, when the
plants are out of flower, they need hot bright days (25-29°C)
and cool nights (10-15°C)
to initiate flower spikes. This can be achieved by setting the pots outdoors
during summer under dappled shade away from midday sun, (to avoid leaf burn).
Feed and water regularly during this period. The plants should spike up when
the temperatures fall in the autumn to below 10oC.
Bring the plant indoors before the
first frost. Once the plants have formed their flower spikes and the buds are
well developed they can tolerate slightly warmer temperatures of 15–20°C.
Note: To help prevent flower and
bud drop, keep plants away from drafts, radiators and other heat sources.
Light:
Cymbidium like plenty of light in the summer, but not full sun. A combination
of long hot days and cool nights during July and August will initiate the flower
spikes. This is also a good time to feed the plants with a high potassium feed
or “bloom booster”. Plants need less light when in bud and/or bloom during the
winter.
Note: Direct sunlight can burn
the bloom and leaves.
Water:
At least once a week throughout the year. Water from the top and allow any
excess to drain away. If the plant is large, it may be easier to submerge it in
a bucket of water before allowing it to drain. Clean rainwater is preferred by
the plant but you can use tap water if necessary. Do not allow the compost to
become waterlogged. Water weekly as a general rule but if the plants are kept
in a warm environment they will need to be watered more frequently.
Note: Never stand the plant in
water for more than 10 minutes.
Feed:
As orchids go, Cymbidium are quite hungry and require regular feeding to
produce good flowers. Feed once a week during spring, summer and autumn using a
balanced orchid fertilizer, such as
Ivens Orchids’ Orchid Feed,
and once every two weeks during the winter. A
high potassium feed or “bloom booster” can be applied from July to September
instead of the balanced feed.
Air Humidity:
Good ventilation (not drafts) and moist air are essential. The humidity can be
raised by placing the plant on a tray of moist gravel or pebbles. 50% humidity
is ideal.
After Flowering:
Cymbidiums will not flower if kept too warm or with insufficient light. They
flower once a year and usually for at least six weeks. Once flowering is over,
cut off old flower stems near to the base. To initiate the next flower growth
they must have cool nights throughout the spring and summer months. Stand your
plant outside towards the end of May until the middle of September. Stand the
plant on a slightly raised base to avoid slugs getting into the pot. Early
morning sun is ideal but provide some shade against strong sunlight. Remember
to continue feeding the plants during this period.
Repotting:
Repotting and dividing are best done in spring after flowering but only if your
plant has outgrown its pot – Cymbidium like to be very restricted in their
pots. A specimen plant can be produced by potting up regularly. A larger plant
usually produces more spikes but sometimes a plant that has been mistreated or
just becomes too old may benefit from dividing as this may regenerate it. Use
orchid compost, such as
Ivens Orchids Cymbidium Compost,
that is moderately free draining whilst retaining some moisture.
Basic Repotting Technique:
Cymbidium are tough plants and
repotting them, and especially dividing them, can be a very strenuous job; you
will need a strong knife and sharp secateurs.
Tap plant out of its old pot or if
very pot-bound you may need to cut the pot away; the plant will be easier to
remove from the pot if it is dry. Inspect the condition of the root-ball: In a
healthy plant, the pot should be almost completely full of firm creamy roots
with pale green growing tips. Generally, a cymbidium will grow in one direction
so it will have a “back”, (where the oldest growths are,) and a “front”, (where
the youngest growths will shoot). If you can see a directional trend in the
plant to be potted bear this in mind when positioning the plant within the pot
and allow space for the new growths to develop without making the plant look lop
sided. Use a pot big enough for you to get two fingers around the root-ball
between the roots and the inside of the pot. Holding the plant upright, feed
compost around the root-ball; there probably isn’t a lot of room between the
roots and the sides of the new pot but pack in as much compost as you can,
making sure it goes right to the bottom of the pot where you want the new roots
to grow.
Cymbidium can be potted firmly.
Always dampen down the compost before potting and water as normal after
repotting.
Dividing:
A plant that needs to be divided will be large and old with many pseudo-bulbs.
Some may be so old they no longer carry leaves; these are known as back-bulbs
and are useful to the plant as storage organs for water and nutrients. The
plant may also have bulbs that are black and soft; these are no use to the plant
and must be removed. When dividing, look at the plant to see if it shows
natural breaks between the growths where it could be divided. The intention is
to divide the plant into two or three good sized plants that have at least 3 or
4 pseudo-bulbs. Tap the plant out of its pot as described in ‘Repotting’ above,
then cut through the plant using a strong sharp knife, trying to avoid cutting
through a bulb or new growth. Once you have your divisions, shake off any loose
compost teasing out any dead or loose bits and remove any old, brown, soggy or
damaged roots. Also remove any old black or soft bulbs, cutting them away if
necessary. The live roots that are left can now be trimmed to about 10 to 15cm;
this will help prevent damaging them during re-potting and allow the plant to
regenerate. Do not worry that it looks to be a large amount of root to remove;
a healthy plant will very soon develop new roots and the plant will benefit by
repotting in this way. Using a pot big enough for the next year or twos growth,
support the plant with the oldest pseudo-bulbs, (the “back”,) at the edge of the
pot and the “front” of the plant toward the centre of the pot. Cover the base
of the pot with a small amount of compost then feed fresh orchid compost around
the root-ball. Always dampen down the compost well before potting. Firm the
compost with your fingers as you go.
The plant should not be watered
for 2 weeks after dividing; thereafter the leaves may be lightly misted and
watered sparingly over a period of about 8 weeks. This allows the new roots to
develop and search for moisture within the compost stimulating good root growth;
over watering would cause the plant to rot. Regular watering and feeding can
resume once the plant starts to feel secure in the pot and new top growth can be
seen.
Although dividing may sound
drastic, provided it is done early in the growth season, (ideally March or
April,) the plant will have sufficient time to produce new roots and still
flower in that season. This is one of the reasons why the plant should not be
over potted: i.e. the bigger the pot, the more energy the plant needs to make
roots and the less energy it has to flower.
Handy Tip:
A leafless back bulb can also be
removed and propagated by potting up in its own, very small pot.
Pests:
Prevention is always better than cure so look for good healthy plants to start
with and keep them that way with a clean environment for your plants. Throw
away old, weak or infested houseplants and maintain good housekeeping in the
greenhouse. Most often seen pests are scale insect, aphids, red spider mite and
slugs. All of these will weaken the plant if left unchecked. If found early
enough, the scale and aphids may be cleaned off with soapy water, otherwise,
treat with a specific systemic insecticide.
Buying Tips:
Always buy good quality orchids from a reputable supplier and look for clean
healthy plants. If buying plants in flower, check the flowers are not damaged
and that the pollen caps are still on the flower, (if these get knocked off by
poor handling or contaminated by poor storage or transport conditions, the
flowers will very quickly discolor or “go over”. Unless you have ideal
transportation and growing conditions, buying a plant with immature buds may be
a mistake as some plants can be sensitive to being moved during the early stages
of flower development. Look for plants whose flower buds look quite plump and
ready to open. Don’t be afraid to buy a plant whose flowers are nearly all out,
especially during the cooler months. Providing they are not kept too warm,
Cymbidiums stay in bloom for many weeks even once all the flowers have opened
and give a marvelous display.
Handy Hints:
Keep your plants clean and healthy by occasionally cleaning the leaves with a
mixture of 1 tablespoon of olive oil and a few drops of washing up liquid mixed
in about 300ml of warm water. Using a sponge cloth, wipe over the leaves with
the mixture. As old leaves die they fall off leaving behind dry brown bases.
These can be removed by stripping or pulling away from the pseudo-bulbs. This
helps to make the plant look tidy and prevents bugs from hiding around the plant
base.
