Cymbidium have highly decorative flower spikes and are one of the least demanding indoor orchids. To flower well, the plants need a distinct temperature drop between day and night during mid- to late summer.
Botanical name Cymbidium
Group Houseplant or greenhouse/conservatory plant
Flowering time Mid-autumn to mid-spring
Planting time Re-pot in mid-spring after flowering
Height and spread 25cm-90cm (10-36in) by 30-90cm (12-36in)
Aspect Bright light, shade from direct sunshine in summer
Hardiness Tender, minimum 8-10°C (46-50°F).
Ensure good light levels all year round, especially in winter. If the plant is kept outdoors in summer, shade it from midday sun.
Cymbidium prefers cooler growing conditions than some other tender indoor orchids. Provide winter growing temperatures between 10-14°C (50-57°F). Keep the temperatures below 30°C (86°F) in summer to prevent damage to the plants.
Plants can be kept outdoors from mid- to late summer (often June to September). However, gradually acclimatise the plants to outdoor conditions in order to prevent leaf scorch from cold temperatures or direct sun.
Flower spike initiation takes place in mid- to late summer, when plants require good light and a distinct drop between day and night temperatures. Placing the plants outside helps to provide such conditions.
To prevent bud-drop, keep the temperature below 15°C (59°F) during flower spike development. Wait until the flowers have opened before moving the plant into a warmer environment for display purposes.
Support developing flower spikes with a bamboo cane. Flowers generally last for six to eight weeks. Once the blooms have faded, cut down the flowered stem to the base.
Cymbidium needs moderate watering during spring and summer, depending on the conditions. Water from above, making sure that excess water can drain away. Do not allow the plant to sit in water. Let the compost dry out a little before the next watering. Plants placed outdoors or in the greenhouse may need more frequent watering in hot weather. Outdoor plants may only need occasional watering if the weather is wet. Reduce watering to weekly or fortnightly in winter.
Apply half-strength general liquid fertiliser every third watering in spring and switch to a high potassium specialist orchid fertiliser in summer. Stop feeding altogether, or feed only occasionally in winter, using half-strength general liquid fertiliser.
Repotting your orchid needn't be a daunting task and can help ensure it grows healthily and flowers well. Cymbidiums are best repotted in spring just after flowering. Below are some useful tips to remember;
- Clear pots are not necessary for cymbidiums as their roots do not seek out the light. They can be useful in enabling you to see if the compost is still moist below the surface however, and so avoid overwatering.
- It is time to repot your cymbidium as soon as it has become too large for its pot or when it has been in the same compost for 2 years.
- Cymbidiums should be repotted after flowering and before the new growths extend.
- Remove the plant from its pot and if it has made a large clump of pseudobulbs, divide them by sawing through the centre of the clump and the rootball with an old breadknife. The pieces should contain no fewer than 5 pseudobulbs otherwise flowering will be impaired.
- Work at the rootball with your fingers, untangling the roots and removing all the old compost.
- Snip off any diseased or dead roots with sterilised scissors or secateurs. These are brown, mushy, shrivelled or hollow in appearance.
- Shorten the remaining healthy roots, that should be white and firm, back to around 15-20cm (6-8in).
- Choose a pot that has enough room for two years' growth (about an extra 10cm/4in in diameter). Avoid using a larger pot unnecessarily, as the compost will stay wet for too long, causing the roots to rot.
- Always use a proprietary orchid compost when repotting.
- Hold the plant at the correct level in the pot and fill in the spaces around the roots with fresh compost, gently firming in as you go and ensuring the compost is pressed down firmly around the perimeter of the pot, so that finally, when the plant is lifted by its stem or leaves, the pot and compost is lifted with it and does not fall off. Loose compost will cause the plant to be unstable and damage the new root tips, stopping them from growing.
- Finally, give the plant a thorough watering ensuring all the rootball is moistened. Drain the plant thoroughly and do not allow it to sit in water.
New hybrids are produced every year, but most of these are sold unnamed. Only specialist orchid nurseries offer named species and hybrids. New introductions tend to be easier to grow, but for the keen grower, here are some species to try:
Cymbidium erythrostylum: Compact with white flowers and red lip.
C. tracyanum: Tall, arching stems of yellow-green flowers boldly striped brown.
C. tigrinum: Compact with hanging clusters of olive-green to yellow flowers with purple-marked lips.
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