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Cymbidium Culture

These orchids are prized for their sprays of large & long last flowers, used especially as cut flowers or for corsages. There are two main types of cymbidiums the standards and miniatures. Some have upright stems while others droop gracefully. LIGHT Cymbidiums come from cool but bright areas in Asia, so in culture they require high levels of light but cool temperatures. Generally in our climate, high level of light are accompanied by the high temperatures of summer, which can be detrimental to the plants flowering potential. During the summer your plants should get the morning light direct but be lightly shaded from the burning rays of the midday & afternoon sun. A spray of water on a hot day will help cool your plants, but they will burn if sprayed while the sun is on them, so ensure that they are shaded before wetting. At this time of the year plants will need plenty of good ventilation. During the winter months cymbids can take direct light, but want to be sheltered from frosts & rain. Leaves should be a medium to golden green in color, not dark green. TEMPERATURE During the summer months cymbidiums can be grown outside in semi-shade quite happily, as long as they are not taking a lot of burning heat & are getting a regular spray of water. As the winter approaches it is best to put your cymbids under shelter. They are quite hardy & will withstand temperatures down to frost level as long as the frosts are not allowed to settle on them. A shelter also protects them from the winter rains. Temperature is a critical factor in the blooming  of cymbidiums. During  February-March the night time temperature can drop a good 10oC or more from that of the heat of the day, & it is this vast change in temperatures that initiates the flower spikes. If the night looks like being warm & humid a spray over the plants of cold water in the evening can be an advantage. A bright and cool location inside is best for winter months. Don’t take cymbids that are in spike into your living quarters, the warmth will cause the buds to die off & drop ruining a whole seasons flowering for that plant. WATER Cymbidiums being semi-terrestrial like a fairly constant supply of moisture. As all of their vegetative growth occurs during the spring and summer months, they need the most water during that period, naturally. Water heavily during the growth season, keeping the potting medium from drying out completely, and reduce water when the pseudobulbs are completed in late summer. Keep barely moist during the winter. Too wet during the colder month will cause rot to set into the roots. HUMIDITY During the summer month humidity from your frequent waterings is generally sufficient as long as there is good air movement available to the plants.  Winter humidity is higher naturally & this will mean that water is required less often. Keep up good ventilation as the air movement helps to prevent fungus (Botrytis) from spotting the flowers or even rotting off the spikes. FERTILISING During the plants growth season, spring through into the late summer, a high-nitrogen fertiliser is best used & can be fed at every second or third watering. From late summer, use a high-phosphorus, bloom-boosting fertiliser such as “Phostrogen” to help form the flower spikes. During the winter months only fertilise about once a month. REPOTTING This can be carried out as the plant finishes flowering, & is usually done every couple of years or sooner if you notice the potting medium breaking down. Shake all the old potting mix off the roots, & at this stage divide the plant if desired. Divisions of green bulbs with leaves must have 3 or 4 bulbs minimum to flower, bulbs without leaves are considered backbulbs, these may be left on the division to add strength, or removed for propagation. Your potting mix, usually medium to coarse pine bark, should hold moisture well. It is best to soak the bark for a few days prior to repotting to allow it to take up moisture, this means the plant has moisture readily available at the roots & a dry mix only allows the water to run straight through, not retaining any for the plant. Select a pot that will allow for at least 2 to 3 years of pseudobulb growth before crowding the pot. Place the active growing bulbs of the division farthest from the side of the pot, spreading the roots over a cone of the mix in the bottom of the pot, and then fill the pot with the media, working it among the roots, by gently tapping the pot. The plant should be firm in the pot when you are finished. The junction of roots and pseudobulbs should be about 15 to 25 mm below the top of the mix. Keep shaded & humid, & water sparingly until the roots have time to heal & start to grow, usually about 4 weeks. The backbulbs that you removed can be buried about half their depth in a  fine bark or peat/sand mix. Keep shaded, warm & damp until new growth sprouts away, sometimes this may take several months, then pot as above. It may take three or more years to produce a flowering-size plant from this method, but it is worth doing.