Cymbidiums are easy to grow and readily available in the temperate regions of Australia. Their spectacular long lasting blooms can occur from May through to December and make an excellent gift or display for indoors. There are a wide selection of colours available and a range of habits such as upright or pendulous and even the number of flowers on each spike. The life span of flowers can be anywhere from 4 – 12 weeks and up to 3 weeks as a cut flower.
Providing a few basic conditions are met Cymbidiums do well in our temperate climate. A lot of growers provide shade houses to protect their orchids from the summer sun or winter frost and hail. 50% shade cloth is suitable, although some further shade may be needed in extreme temperatures. Place the orchids on raised benches with gravel underneath. This helps provide the humidity that orchids enjoy in summer. If you have only one or two plants or don’t have room for a shade house, placing under a deciduous tree also works well as long all the other growing conditions are met.
If you have a large collection of orchids an overhead sprinkler system helps maintain your orchids in peak condition. For smaller collections hand watering is adequate and also helps you monitor your plants health. Space your plants to receive maximum light and air flow.
One of the main reasons for lack of flowering in cymbidiums is not enough sunlight. When there is enough light the leaves tend to be a golden green rather than a darker green which indicates not enough light. Plants can be placed out in the winter sunshine being careful to protect them from frosts and watch out for snails and slugs that love the developing flower spikes. The more light the plants receive the sturdier the spikes and blooms will be. Make sure you stake the spikes and face towards the strongest light source.
Potting Mix and Repotting
Cymbidiums are semi-terrestrial with fleshy roots therefore the potting medium needs to be free draining, but also able to hold moisture to nourish and support the plant. Heynes sell a range of good quality potting mixes to suit your needs.
The best time to repot your Cymbidiums is just after flowering has finished. This gives them a long growing season before next years flowering. Small plants can be repotted most of the year, avoiding times of extreme heat. Cymbidiums do best when potted with room for one or two years growth. Plants will not thrive if potted in too big a pot. Repotting can be done every 2-4 years depending on growth.
Before repotting your plants carefully untangle the root system shaking off all the old potting mix. Large plants with extensive root systems can have the bottom quarter of the roots cut off making it easier to untangle the roots with minimal damage. Remove any shrivelled dead roots. Try to keep each division to 3-4 bulbs with leaves on them. This will give you the best chance of flowering next year. If your new divisions throw up multiple growths, remove all but one to allow for maximum bulb development and better flowering.
Back bulbs, which are the old leafless bulbs, can be removed, cleaned up and planted in small pots to produce new plants. New growth should be seen anywhere from 3-6 months. It takes about 4 years for these new plants to flower so patience and space is needed if you choose to go down this path. Some sources suggest leaving an old back bulb on your divisions for better flowering.
Your newly potted plants will need some extra shelter for a few weeks before returning to their usual growing position.
Cymbidiums need to watered well during the warm weather and also kept evenly moist throughout the cooler months. Orchids left to dry out will most likely survive but will not flower well, if at all the following season. Rainwater is preferable as you will get less leaf burn, but Adelaide’s saline water is perfectly acceptable. When using tap water be sure to water each pot several times to flush out all the salts that can accumulate at the bottom of the pot. Even if you can occasionally collect rainwater to flush out the salts, this will benefit your plants. Don’t forget to group pots according to their size for ease of watering. Small pots will dry out quicker than larger pots. Water on the flowers can greatly affect the quality of the blooms so it is a good idea to put your orchids under cover or inside when flowering.
To get the best from your cymbidiums apply a slow release fertiliser suitable for orchids in spring. From spring through to may you can use liquid fertilisers such as Thrive Orchid Liquid Plant Food or Manutec Orchid Bloom booster while spikes are forming. At other times of the year you can use Manutec Orchid Food. Alternating with organic fertilisers such as Powerfeed or Charlie carp at any time of the year should give great results. There are many different views on fertilising which you may want to explore, choosing the routine that gives the best results. Watering mid to late afternoon in the hot weather decreases the temperature of the plant which can encourage flowering.