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GARDENING, Etc.
Sunday, August 10, 2003
Photo: Texas A&M Hort |
Growing Phalaenopsis
By Lynn Rawe, CEA- Horticulture
Texas Cooperative Extension
Bexar County
|
Photo: University of California, Davis |
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.
Light
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.
Temperature
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.
Humidity
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.
Watering
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.
Potting Media
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.
Fertilizing
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.
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