Orchids provide winter elegance
Cymbidium orchids are easy to grow and, if you give them the right conditions, they will reward you with flowers year after year.
Cymbidiums are regarded as the queen of winter indoor plants - their glorious blooms providing months of colour from now until September. They are easy to grow, relatively fool-proof and exceptionally generous plants.
During the flowering period, they may be kept indoors for you to enjoy the flowers at close quarters and, come spring, they can be placed on a shady patio or left in filtered shade under a large tree in the garden. As with all plants, they require light, air, water, food, a support medium and occasionally some pest control.
How do you get the best out of your cymbidium? Follow this checklist:
Place your cymbidium in a protected spot away from direct sun and wind. It will thrive in an area which is warm, receives bright light and is well ventilated. If it gets too little light, it will not flower well. In winter, place it indoors or on an enclosed patio in a spot which receives morning sun and late afternoon light. In summer, it can be placed under trees that offer filtered light or on a shady patio. Indoors, place it next to a window that gets bright light, but ensure there are no draughts.
Gardening expert Joan Wright says, "The colour of the leaves is a good indication of the correct light. Leaves should be slightly yellow-green; deep green leaves mean there is insufficient light. Green flowers need more shade than pink or red flowers."
Temperature and humidity
Cymbidiums will tolerate temperatures as low as -2 degrees Celsius but if your garden receives heavy frost you must protect the plant. In frost-free areas of the country, cymbidiums are ideal outdoor patio plants, but subtropical areas are too warm for them. The low night temperatures on the Highveld in winter offer the best growing conditions for cymbidiums, but their flowers and buds must be protected from frost.
Humidity is very important to cymbidiums. The humidity on the Highveld can plummet down to 25% in winter. Cymbidiums start to feel uncomfortable when it gets below 40% humidity. The answer is to place the plant on a tray of pebbles lying in water. The plant will appreciate its own personal micro-climate. When the temperature exceeds 28 degrees C, the plants will benefit from a misting on the leaves.
It is best not to overfeed cymbidiums. However, the right amount of fertiliser is important for bulb growth and subsequent good flowering the following year. Feed them with a balanced orchid fertiliser or slow release fertiliser at the recommended strength in spring and a liquid fertiliser during the growing season.
The plant should be watered all year round, but avoid watering if the soil in the pot is damp. However, if they are allowed to dry out too much, flowering the following year will be poor. As a general guide, water two to three times a week in summer (more if the weather is extremely hot), and once a week in winter. In spring and autumn, watering about once or twice a week is sufficient. It is best to water in the morning and, if possible, use rainwater.
Dividing and re-potting is best done between October and December. Avoid dividing the plant too often, as flowering will be impaired. Each division must have at least three mature bulbs with leaves. Use a mixture of sieved bark and marble chips as a potting medium (never use garden soil) and enlarge the standard drainage holes found at the base of most plastic pots. Avoid compressing the medium and water generously after potting. Never allow the medium to dry out completely.
Pests and disease
Outdoors, keep your orchids off the ground, as slugs and snails are the worst enemies of these plants. Regular use of snail bait (a small quantity around the plants every two weeks in the flowering season) gives good control.
Scale insects can be treated with Chlorpyrifos twice, at an interval of two to three weeks. Red spider mites can be treated with spidermite spray. In the case of rot and fungal disease, the plant should be unpotted, cleaned and all the diseased tissue cut out. The wounds should be dusted with sulphur and the plants re-potted in new potting mix.