General Information
The Phalaenopsis, or “Moth Orchid,” is the most common orchid because of its ease of culture and the availability of flowering plants year-round. Phalaenopsis are easily grown in the home and stay in bloom for a long time. A mature Phalaenopsis will be in flower for much of the year with graceful inflorescences laden with good-sized blooms. From pure whites to unusual spotted harlequins, Phalaenopsis are sure to please. Unlike many other orchids, Phalaenopsis can be repotted at any time, though it is usually best to do so when they are not in flower.
Growing Phalaenopsis orchids requires windowsill light and constant moisture.
Phalaenopsis do very well as house plants, growing and flowering in a moderately bright windowsill.
Each year, a Phalaenopsis will develop two or three new leaves.
Once the growth phase is complete, usually in the fall, a flower spike will emerge from beneath the second or third leaf from the top.
Sometimes we need to help a Phalaenopsis grown in a consistently warm house to understand that it is autumn by exposing it to lower (60° F) temperatures for several nights to instigate a flower spike.
Phalaenopsis orchids flower from late winter into spring.
Culture for Doritis, a related genus, believed by some to be conspecific with Phalaenopsis, and Doritaenopsis, a hybrid between the two genera, is the same as for pure Phalaenopsis.
Light Requirements
Phalaenopsis are “low” light orchids. In nature, they grow attached to the trunks of large trees, under the leafy canopy, so they are familiar with bright, yet indirect light filtering through the canopy. They easily grow in a bright window, with little to no sun. An east-facing window is ideal in the home; shaded south or west windows are acceptable. The leaves of a Phalaenopsis should be olive green. If they are darker, it means the plant is not receiving enough light; red-tinged leaves mean the plant is getting too much light.
Once the plant is in bloom, you can place it anywhere in the house, out of direct sunlight. If in a greenhouse, 70 to 85 percent shade is required. Think of a greenhouse with plenty of natural light, but with the glass whitewashed to diffuse the direct rays of the sun – this is the exposure they love. You should see no shadow if you hold your hand twelve inches from a plant’s leaves.
You can get good phalaenopsis orchid care even indoors, away from windows, as long as there is a good light source, either natural or artificial, to ensure the plant gets enough light. Artificial lighting can easily be provided. Four fluorescent tubes in one fixture, supplemented by incandescent bulbs, are placed 6 to 12 inches above the leaves, for 12 to 16 hours a day, following the natural length of the day.
Temperature Requirements
Phalaenopsis orchids are ideal for indoor temperatures. Temperatures for Phalaenopsis should usually be above 60° F at night and range between 70° and 80° F or more during the day. While higher temperatures will initiate faster vegetative growth, higher temperatures must be accompanied by higher humidity and air movement, with maximum recommended temperatures between 80° and 90° F. Night temperatures to 55° F are desirable for several weeks in the autumn for flower initiation. Fluctuating temperatures may cause bud drop on plants ready to bloom. Make sure to keep them away from air conditioners and heaters, as well as hot or cold drafts.
Water Requirements
Water is particularly important for the phalaenopsis. Since they have no substantial water storage organs besides their leaves, they should never be allowed to completely dry out. The frequency of watering will depend on the potting media. Bark holds less water than moss. If your phal is potted in bark, watering once every 7 days is generally sufficient. If your plant is potted in moss, water it when the top appears dry. Generally Phalaenopsis require watering about once every 2-4 days under outdoor conditions. The amount of light and heat your plant receives will also influence watering frequency. In the summer months, more frequent watering will be required, whereas in the winter, less will be needed. After a few waterings, you will be able to tell by the weight of the pot whether it is time to water again. When in doubt, wait a day.
Water your Phalaenopsis orchids early in the morning. This ensures complete evaporation of water from the leaves and crown by nightfall. Water with rainwater, distilled, or reverse osmosis water when the potting mix approaches dryness. Never use softened water from a water softener.
“Don’t water the leaves and flowers of your orchids”
You should only water the roots of your orchid, as wetting leaves and flowers can cause several problems. If you pour water over the top of your orchid, you’re likely to leave standing water in the crown, where the new leaves are growing. If you repeatedly do this, standing water will encourage the formation of crown rot, which can damage the plant very quickly or even cause it to die.
“Don’t mist your Phalaenopsis orchids”
Many people advise spraying orchids with a fine mist of water to increase the humidity of the air in the immediate vicinity. Generally, however, this is not a good idea, as it is not an effective method of increasing local humidity, and water collects on leaves and flowers. This can lead to the formation of mould spots on the leaves or, more commonly, on the flower petals.
After watering your orchid, it’s vital to ensure the water is well-drained before putting it back on display, and that the roots are not left in standing water for any length of time. The roots will not tolerate this and could rot.
The Ice Cube Controversy
There is much conflicting advice as to whether or not you should regularly use 3 ice cubes to water your orchids. It’s often advised as a good idea, as it encourages you not to overwater your orchids due to the small amount of water contained in the cubes. For those growing orchids in colder conditions, at the bottom end of the ideal temperature range, using ice to water your orchids can add to the cold stress for the plants.
In warmer climates, watering your orchids with ice will not have a significant negative impact. The ice will melt quickly and will not significantly affect the temperature of the roots or the plant. However, in warmer climates, your orchids are likely to need more water and using ice cubes may not provide sufficient hydration.
WE STRONGLY ADVISE AGAINST THIS TECHNIQUE
Humidity Requirements
Phalaenopsis orchids are monopodial, lacking pseudobulbs that help store humidity. Because of this, the recommended humidity is between 50 and 80 percent.
Utilizing a humidity tray is one of the best methods. These trays are nothing more than a water container filled with gravel. The gravel-filled trays are filled with water to a level just below the surface. To prevent the plants from sitting on the constantly wet gravel, plants are set on small pot feet or pieces of plastic or metal grating placed over the trays. Wrinkle-free, plump leaves indicate a well-hydrated plant.
In humid climates, such as in greenhouses, it is critical that the humid air is moving. Leaves must be dry as quickly as possible, always by nightfall.
“Don’t leave your Phalaenopsis orchid roots sitting in water”
Flowering
The Phalaenopsis is one of the longest-blooming orchid genera, with blooms lasting 2 to 6 months before dropping. Phalaenopsis have been known to flower 2 or 3 times a year once they’ve reached maturity. After flowering, the stem turns brown; cut it off close to the plant’s base, where it emerged.
Pruning for Re-Flowering
Phalaenopsis orchids will re-flower on old stems with a new stem emerging from a triangular node along the stem. To initiate re-flowering, your orchid will need a little more attention than usual. The excitement of seeing your orchid flower for a second time, however, more than makes up for the small investment of time and effort required to initiate re-flowering.
Phalaenopsis orchids use a lot of energy creating the large, beautiful blooms they are prized for. Under normal circumstances, your orchid enters a period of rest called dormancy once flowering has finished. Dormancy allows the plant to rest and replenish the nutrients consumed during flowering. Nutrients and water are stored in the plant’s leaves until they are needed for growth and flowering. Dormancy typically lasts for 6 to 9 months, and your orchid may reflower on its own. But sometimes orchids need a little help activating the natural rhythm that leads to flowering.
- Good light conditions are essential to give your orchid enough energy to stimulate re-flowering. Position your orchid in a bright window, ideally south or east facing, with plenty of indirect sunlight.
- To stimulate re-flowering, your Phalaenopsis orchid should ideally experience a temperature change between day and night. An ideal daytime temperature is between 70–85°F (21–29°C) and a minimum nighttime temperature of 60–70°F (16–21°C).
- By increasing the humidity of the local environment, you are creating a more favorable climate for orchids to grow and re-flower. Try humidity trays.
- The vegetative stage after flowering is when fertilizing is most important. I like to make sure I fertilize my orchids roughly every 2 weeks with a dilute fertilizer solution during this growth phase.
Cutting Spikes on a Phalaenopsis
For most orchid species, the flower spike should be pruned after flowering. This is usually indicated by the plant itself, which the stem turns brown. For the Phalaenopsis, it can be a little complicated to know what to do and, to complicate matters further, there are several schools of thought on the subject.
On most Phalaenopsis, the flower spike will turn brown after the plant has finished blooming. It may not turn brown all the way down, though. One school of thought recommends that you cut the stem above a stem node and let the plant re-flower as a branch from the existing stem. Another school of thought recommends that you always cut the flower spike off at the base when the flowers drop. The flowers draw energy from the plant, so cutting the spike off completely allows the plant to gather its energy for an even more spectacular bloom in the future. Allowing the spike to branch results in more blooms sooner, but it draws energy from the plant, often resulting in smaller blooms.
There seems to be an exception to every rule in orchid culture. Some Phalaenopsis should not have their flower spikes cut. These Phalaenopsis have species like Violacea, Amboinensis, Cornu-Cervi, etc. in their parentage. These Phalaenopsis usually only carry a few flowers at the end of a spike and will carry sequential blooms on the same spike for a very long time, seemingly forever. The only reason to cut these spikes is if the plant becomes too unruly.
Each Phalaenopsis spike will have at least a few nodes covering it before flowering. Each of these nodes has the potential to branch out during or after the initial bloom.
Fertilizer Requirements
A healthy Phalaenopsis will greatly benefit from the addition of fertilizer, but adding fertilizer will not fix most problems with an ailing orchid. Always use a dilute concentration of fertilizer, but use it more frequently, rather than using the full concentration less often. This is mainly due to the nature of the growing medium. Phalaenopsis orchids are often grown in bark or a combination of bark, sphagnum moss, perlite etc. These do not retain moisture and nutrients in the same way as soil, so regular application of readily bioavailable nutrients will be more beneficial to your orchids.
Phalaenopsis orchids generally do not need much fertilizer, if any, during the flowering phase. It is during the vegetative phase that fertilizer is really needed, to give the plant the energy it needs to start developing new stems, buds, and flowers.
Recommended Fertilizers:
- Balanced Growth Fertilizer: 20-20-20 (NPK) – 2 grams per liter of water – Spray once every two weeks (14 days)
- High Phosphorus Blooming Fertilizer: 0-52-34 (MPK) – 1 gram per liter of water – Spray every two weeks (14 days) – Use only during the vegetative phase
Repotting, Substrates and Propagation
There are two main reasons why a phalaenopsis orchid might need to be repotted. The first is when the growing medium begins to deteriorate and decompose. The second is when the roots outgrow the pot in which the orchid is growing. Repotting is usually done every one to three years. Mature plants can grow in the same container until the substrate begins to decompose, usually after two years.
“Root rot occurs if plants are left in soggy soil”
Orchids generally prefer to be root-bound, so do not use a pot larger than necessary. It is advisable to choose a transparent pot for Phalaenopsis orchids. Orchid roots contribute to photosynthesis and energy production, so giving them access to light contributes to the overall health and vigor of the plant. Since the roots absorb a lot of moisture and nutrients directly from the air, having numerous ventilation and drainage holes will allow good air circulation to the roots of your orchid.
The most common growing medium is a tree bark-based mixture, although any fast-draining substrate can be a valid alternative. Phalaenopsis are successfully grown in perlite, expanded clay, peat, bark, sphagnum moss, and various mixed substrates. As long as we adapt to the characteristics of the chosen growing medium, we can achieve good results.
Brown ones are unhealthy or dead roots.
It is good practice to evaluate the roots during repotting. Any roots that appear damaged or diseased can be removed manually or with a pair of sharp, clean garden shears. Don't worry too much about removing diseased roots. The plant will thrive much better with a reduced volume of healthy roots, compared to a larger volume of roots with a sick or diseased section.
Phalaenopsis plants, being monopodial, cannot be divided. They will naturally produce "baby" orchids, known as keikis. These are identical copies of the mother plant and normally appear on an old or new flower spike. After about a year, the keiki can be removed from the mother plant and placed in a separate pot. The keiki is ready when it has two or three leaves and its own roots about 8 cm long.
Pests and other Phalaenopsis related problems
Fungal and bacterial diseases of Phalaenopsis are common due to the high humidity levels they need to survive. Fungal agents cause problems such as root rot, leaf spots, leaf dieback, and flower spots.
