AMES, Iowa -- Orchids are a popular and colorful addition to any home setting. In this installment of Yard and Garden from Iowa State University Extension and Outreach, Aaron Steil, associate director of Reiman Gardens, answers some common questions about how to care for and grow orchids at home for all to enjoy.
What is the proper care for a moth orchid?
Moth orchids (Phalaenopsis spp.) are one of the easiest orchids to grow indoors. Moth orchids grow best in bright, indirect light. Direct sun may actually harm the foliage. Ideal sites are east- and north-facing windows. Plants in a south window will need to be shaded with a sheer curtain. Phalaenopsis orchids will not grow or flower well in poorly lit areas. Fluorescent lighting can be used to supplement natural lighting in poorly lit areas. Place the fluorescent fixture 6 to 8 inches above the plants. Keep the lights on for 12 to 16 hours each day.
Moth orchids like a bark medium that is kept evenly moist. Plants should be watered well and then allowed to dry slightly between waterings. Water moth orchids more frequently when plants are actively growing and during bloom. Plants are susceptible to root rots and death when watered too frequently.
Moth orchids prefer daytime temperatures of 70-80 degrees Fahrenheit and nighttime temperatures of 60-70 F. Cool nighttime temperatures of 55-60 F in fall help initiate flower development. Avoid exposing plants to temperatures below 55 F.
Phalaenopsis orchids require a relative humidity of 40-60 percent. Unfortunately, the humidity levels in most homes during the winter months are well below this range. Humidity levels indoors can be increased with a room humidifier or by placing the plant on a tray or saucer filled with pebbles and water. They bottom of the pot should be kept above the water line. The evaporation of water from the tray will increase the relative humidity in the vicinity of the plant.
What other orchids are easy to grow indoors?
Moth orchids (Phalaenopsis) are the most common species available to home gardeners because they have a long bloom period, will tolerate the light levels found in most homes, and flourish in typical home temperatures. Other species of orchids are also available and good candidates for home gardeners.
Lady slipper orchids (Paphiopedilum) have unique solitary, long-lived flowers. They prefer watering frequency, temperatures and light levels very similar to moth orchids.
Dancing lady orchids (Oncidium) have large panicles of small, long lasting flowers, some of which are very fragrant. Cane orchid (Dendrobium) have medium sized flowers on coarse cane-like stems. Corsage orchids (Cattleya) have large, colorful, fragrant flowers. All three of these species need bright indirect light and temperatures of 70-80 F during the day and 60-70 F at night. Watering frequency for these species is different from moth orchids as they have pseudo-bulbs or thick fleshy stems that hold water and therefore should be allowed to dry thoroughly between waterings.
Cymbidium orchids (Cymbidum) have long-lasting sprays of flowers often from early winter through early summer. Plants need consistent moisture and bright, indirect light. Cymbidums flourish in cooler temperatures than most orchids, especially in winter (winter temperatures of 45-55 F at night and 65-75 F during day – maximum summer temperatures of 75-85 F) and require a distinct drop between day and night temperature in late summer (50-60 F at night) to initiate flower development.
Should I water my orchids with ice cubes?
Watering orchids looks very different from other indoor plants. They are often grown in coarse bark or coarse sphagnum moss. This soilless media provides a good balance of water and air for the large roots of these epiphytic plants. Water runs freely through the media and when dry can be difficult to adequately wet. Ice cubes are occasionally recommended as a method to provide water slowly to fully wet the media without overwatering.
Many growers advise against this method, as it has the potential to damage roots or leaves with low temperatures or allow the soilless media to remain too wet, too long, especially if the soilless media is sphagnum moss. Research on watering moth orchids (Phalaenopsis) grown in bark media showed that moth orchids watered with ice cubes saw no change in quality or display life compared to those watered with equivalent amounts of room temperature water. This means that for some gardeners, watering moth orchids in bark media with ice cubes is an option. For some gardeners, this method of watering may work, but as with any method of watering, care is needed to not allow the media to stay too wet too long and to allow media to dry slightly between waterings. Plants are susceptible to root rots and death when watered improperly.
How often do I repot my orchid?
Most orchids are grown in coarse bark or sphagnum moss media. This soilless media provides a good balance of water and air for the large roots of these epiphytic plants. Over time this media breaks down and holds more water and less air. To avoid damage to roots, repot and replace the media every two to three years.
To repot, carefully pull the plant from the container and remove old bark or sphagnum moss. Trim out any dry or soft roots with sharp, clean pruners. Place a small mound of media in the center of a clean container and spread the roots over it. Gently, but firmly pack media around roots to hold the plant upright in the container and water thoroughly. Most orchids prefer to be slightly pot bound, so it is not necessary to increase container size with every repotting. Only move up one size container when roots will no longer physically fit in the container.
Why won’t my orchid rebloom?
Frequency and timing of orchid bloom depends on species. Some orchids bloom annually, others continuously. Many species, including the popular moth orchid (Phalaenopsis), typically bloom in winter and early spring months.
One of the primary reasons an orchid does not bloom is improper light levels. Most orchids require bright, indirect light. These light conditions are most commonly found in a south or east facing window. If adequate light is not being provided, find a brighter location or provide supplemental light utilizing fluorescent or LED light. Orchids that do not receive adequate light often have dark green leaves. While this looks healthy, a medium, grassy-green color is an indication that plants are receiving the appropriate amount of light.
If light levels are appropriate, then other factors that can prevent bloom should be investigated. Orchids that have not been adequately fertilized will not flower well. Most species need to be fertilized regularly with a weak solution of balanced fertilizer (mixed at ½ or ¼ strength), especially over the summer months while actively growing.
Some species, such as Cattleya, are photoperiodic and require short-day or long-day conditions. Other species, such as Phalaenopsis, do not require these conditions. Research your species to determine if day-length is a factor that needs to be considered for flowering. In most species, it is not day-length alone that initiates flowering, but it may be an important component.
Many species of orchids, including Phalaenopsis, need a temperature drop at night to trigger flower formation. In late summer, early fall, provide a 10-15 degree drop in temperature at night - ideally down to 55-65 F for three to four weeks. Warm days and cool nights naturally occur in the fall, which is one of the reasons so many species bloom over the winter months.
Looking at factors such as light, temperature and fertilizer and making certain they are ideal for the species of orchid being grown will ensure beautiful blooms year to year.
For more information, contact Aaron Steil at 515-294-8953 or firstname.lastname@example.org.
Photo Credit: Indoor orchids, by snowflake26/stock.adobe.com.