Sunday, August 10, 2003
By Lynn Rawe, CEA- Horticulture
Texas Cooperative Extension
Phalaenopsis have become very popular. The main reason for their popularity is the flowers last three months or longer on a graceful arching spike with many flowers. Phalaenopsis flower in late winter and spring. Phalaenopsis are easy to grow in normal home conditions if extra humidity is provided. Remember basis of horticulture is the same for all plants, even orchids. If you can grow plants, you can grow orchids.
Compare our landscapes. Some of us grow impatiens in shady landscapes and some of grow lantana in sunny landscapes. We select the plants that grow in the conditions that exist in our landscape. Use these same principles for growing orchids. If you have a sunny growing area, grow orchids that require a sunny location such as Oncidiums, Dendrobiums and Cattleyas. If your growing area has low light, grow Phalaenopsis and Paphiopedilums.
Phalaenopsis grow in low light conditions. Their exact requirement is 1,000 to 1,500 foot candles of light. You can measure the light with a light meter or judge by the growth of the plant. Place Phalaenopsis in an east or south window. The foliage will appear yellow-green not dark green if the light is correct. Dark green leaves or the new leaf growing longer and more narrow than the old leaf indicates the light is too low.
Phalaenopsis will grow under artificial light. Grow Phalaenopsis 9 to 12 inches under fluorescent grow lights or 4 to 6 feet under 400 watt high intensity discharge lights or high pressure sodium lights. If your Phalaenopsis does not have a flower spike growing by February, move it where it will receive more light. Even a small incandescent light can make a difference.
The temperature range for Phalaenopsis is 60 F to 85 F. The normal home temperature of 72 F to 78 is fine for Phalaenopsis. Allowing the temperature to drop below 60 F will endanger the plant. Check the temperature at the window sill during the winter. In the fall, allow the night temperature to drop down to 60 F for three weeks. This temperature drop will induce the flower spike. The flower spike should start to grow about three weeks after the cold treatment. The flower spike will grow in the direction of the source of greatest light.
The flower placement on the spike is important. All the flowers will face the source of greatest light. Once the flower spike starts growing, the plant should always face the same direction. When you move the plant to water it, place the plant back facing the original direction. If growing at a window sill and the flower spike grows into the window, do not turn the plant around. If you do, the spike will continue growing to the window and you will end up with a crooked spike.
Phalaenopsis like most epiphytic orchids grow best with the humidity 50% or higher. Most homes have a humidity of 30 to 40%. To create high humidity around the orchid, provide a way for water to constantly evaporate around the plants. Place gravel in a pan or saucer. Place the plant on the gravel. Keep water in the pan or saucer level with the top of the gravel. Do not allow the water to touch the bottom of the pot. This will create a micro-environment of high humidity right around the plant. Pans to fit window sills or tables can be custom ordered from sheet metal companies. Misting does not substitute for humidity. Humidity is in the air. Misting is not the same. Misting causes leaf spot diseases if there is not good air circulation. Do not mist.
Water when the orchid needs water. Water needs are influenced by humidity, potting media, type of pot, size of pot, time of year and the orchid. Over watering is the biggest killer of orchids. So when in doubt, do not water.
Orchids require a thorough soaking. Do not just give them sips. Phalaenopsis are epiphytic plants. The roots on epiphytic orchids are covered with a spongy tissue called velamen. In nature, this tissue absorbs water and nutrients from the air. In cultivation, the orchid roots have this same ability. Orchids require more air than terrestrial plants around their roots. Look at the velamen on the roots. The tip should be shiny green or red. The velamen should be plump and shiny gray or silver. As you water, watch the velamen turn greenish. This color change is a good indication that you are watering thoroughly. When the velamen turns back to gray or silver, wait a couple of days and water.
If the orchid is potted in a peat based media, stick a pencil into the media as you stick a toothpick into a cake. If the pencil comes out of the media with peat on it or with the wood wet, do not water. Over watering turns the velamen brown and mushy and the roots lose their ability to absorb water.
It does not matter what media you use to grow orchids, but how you manage the orchids in the media. Remember, the roots need air. Over watering is the worst problem. The water displaces the air in the media. Use a media with large particles so there is plenty of space for air. Every orchid grower has their favorite media and are constantly trying new ones. Find one that works for you and stick with it. Peat based media are becoming popular because of the availability. These media all have different formulas. Many of them have a wetting agent which keeps the soil wet for a longer period of time.
Repot Phalaenopsis in the late spring or summer after it completes flowering. Wash all the old media off the roots. Using sterilized pruning shears, cut off any damage or diseased root (brown and/or mushy). Healthy roots are white and turgid. Pot the plant back in the same pot or a bigger pot depending on the size of the roots. Pot to fit the roots.
Fertilize every two weeks with a half strength fertilizer. Use a 3:1:1 ratio fertilizer if the orchid is potted in bark media. Fertilize with a balance ratio 1:1:1 if potted in peat based media. Orchids, like other plants, slow their growth down in the winter. Reduce the amount of fertilizer during the winter. Fertilize Phalaenopsis with a 1:3:1 (high phosphorus) ratio fertilizer in November when the plants are setting their flower buds.