Cymbidium (Sim-bid-ee-um) Culture
The Cymbidium is commonly known as the King of Orchids and is native to the cool highlands of China and northern Asia. Cymbidiums are prized for their large stems of fragrant flowers found in multitudes of colors which can remain in bloom for up to 3 months. When the flowers have expired, the bloom stem should be removed at the point where it had emerged from the plant.
To ensure good growth along with profuse flowering, Cymbidium requires bright light throughout the year. They prefer some direct sun and do best when receiving the light source from above rather than from the side of the plant. While growing in your home, a south or west exposure is recommended.
Cymbidium does best when grown outdoors during the months of June through October. Hung from a tree or the overhang of your house, placed in a sunny screened porch, tucked in the bushes where they can receive some dappled sunlight, or direct morning sun is ideal. Cymbidium can benefit from higher intensities of light as the day length decreases towards fall and into winter, and vice-versa for the spring and summer. Try to provide as much light as possible for your plant throughout the year without causing sun burn on the leaves. Once your Cymbidium is in the flowering stage it is best to shade it from any direct sun to prolong the life of the blooms.
An important cultural element for Cymbidium is that they do best when exposed to a 10 to 15 degree differential between day and night temperatures. It is for that reason we recommend to grow Cymbidium outdoors from June until mid October. While growing outdoors these plants do not mind periodic temperature dips into the 30’s as long as it does not freeze. It is time to bring your Cymbidium indoors once the temperature consistently nears the freezing mark either during the day or night. Try to push the threshold of low temperatures as long as possible while outdoors in the fall, but avoid freezing the plant. It is very important to subject your Cymbidium to very cool temperatures to set the bloom spikes.
Once you have brought your Cymbidium indoors for the growing season of October through May, it is best to place them in an area that experiences a cool nighttime temperature of 55 degrees or lower, but not below freezing. In the home this can be best achieved by using a garage window, a basement window or a spare room that you are able to reduce the nighttime heat source significantly. At this time the light level can be compromised because it is more important to provide the cool temperatures than it is to provide the bright light. Continue to grow your Cymbidium in a very cool area until at least the first of December, or until the area experiences close to freezing temperatures. Again, it is a must to subject your Cymbidium to very cool temperatures to set the bloom spikes.
Once the bloom spikes are set and developing, the Cymbidium still prefers to be in a cool area of no more than 55 degrees at night and no more than 75 degrees during the day. If the buds turn yellow and die off, the temperature was too warm either during the day or night. As your Cymbidium buds develop and are beginning to open then it is alright to move the plant to an area of your home that is more in harmony to the temperatures you are living with. Keep in mind that the cooler the temperature, the longer your Cymbidium flowers will stay in bloom.
Proper indoor watering requires allowing the bark mix to become dry just beneath the surface between watering cycles. Factors such as how root bound your pot is, how much light the plant is receiving, and what size pot it is in, will all play a role on how fast it dries out. Typically while growing indoors a good thorough watering once a week should be sufficient. When your plant is flowering or is very root bound, watering every 4-5 days is needed. When watering, water the bark thoroughly until water runs freely from the bottom of the pot. Always remove your pot from any decorative container to allow for proper drainage. Never allow your pot to stand in any water as this will cause root rot. Never use softened water on any of your orchids.
For outdoor growing it is best to maintain slightly more moisture than for indoors. During the highest temperature periods (mid summer) we recommend to keep the Cymbidium moist but not soggy. A watering two to three times a week is usually needed during that period. As the temperature begins to drop towards the end of the outdoor season, begin letting the bark become dry just beneath the surface, much like the indoor watering schedule. While outdoors the natural rain on the plant is highly beneficial.
Cymbidium are fairly active growing plants, and therefore fertilizer is essential for good growth and flowering. We recommend applying a 20-20-20 or similar balanced type fertilizer once every 2 to 3 weeks throughout the entire year. A safe dilution ratio is one level teaspoon of fertilizer mixed in one gallon of water. Do not over-fertilize as this will cause permanent root damage.
Since Cymbidium are cool growing orchids native to high elevations, they are not so particular when it comes to humidity needs. While growing outdoors they receive ample humidity in our Wisconsin summer climate. When growing indoors during the heating season it would be beneficial to provide some added humidity by placing the plant on a humidity tray, misting the leaves in the morning or grouping the Cymbidium together near other plants.
We recommend repotting Cymbidium every two to three years. If you are not experienced or comfortable doing this yourself we offer the repotting service at our greenhouse for a small fee. Your recently purchased Cymbidium may be ready for repotting as soon as it has finished flowering. Inquire with us as to when your individual plant was last repotted. It is best to repot Cymbidium after flowering is completed in the spring or early summer.
Cymbidium may be divided if the plant has enough pseudobulbs to safely do so. A division should consist of four pseudobulbs minimum, all having leaves. This will ensure that the plant will have enough strength for future growth. Larger divisions of 6-10 pseudobulbs are preferred, which in turn will make for a specimen plant the next blooming season. If your plant is not dividable at this time simply repot it into a larger pot.
To make a proper division, begin by examining your plant for a natural line between the pseudobulbs that will give you equal halves if possible. Using a large stiff knife, make a cut through the plant and root mass to make the division. Try to keep the root mass intact as much as possible which will prevent transplant shock. Some leaf-less pseudobulbs can be removed and discarded at this time.
A note about orchid viruses: most commonly the transmission of orchid viruses is caused by using the same cutting tool on multiple plants. The most effective method to reduce virus transmission from plant to plant is to briefly flame sterilize all your cutting tools between use on each plant. A simple Butane torch or a gas stove are handy items for this purpose. This practice should be implemented when repotting as well as when cutting off expired flowering stems.
Once your division is made, select a new pot in the appropriate size to allow for another two years of growing. Unfortunately there is not a set rule for choosing the proper pot size, but generally you will need to increase the pot size by one to two inches. Do not use too large of a pot because these plants like to be somewhat crowded, even after repotting. The Cymbidium prefers to be potted into clay pots for the benefit of the porosity offered by the clay as well as the stability from the weight.
Place the plant into your selected pot and add our moistened fir bark orchid potting mix around the roots. Position the plant in the pot so the junction of the plant and roots is buried one half inch below the potting mixture. Pack the potting mixture firmly with a blunt tool to ensure the plant is secure in the pot. Wait about one week and then water thoroughly.
Happy growing, from Orchids Garden Centre & Nursery!