University of Vermont Extension
Department of Plant and Soil Science
Winter News
Article
ORCHIDS FOR
YOUR VALENTINE
Dr. Leonard Perry, Extension
Professor
University of Vermont
Orchids
are exotic, elegant, and romantic. That's what makes them the
perfect gift for
your special someone on Valentine's Day.
Orchids
come in all colors except black (although there are orchids that are
almost
black), in all sorts of beautiful and bizarre shapes, and in a wide
range of
sizes. Although most garden centers carry reasonably priced,
easy-to-grow
varieties (mostly tropical species), in the natural world there are
more than
20,000 species of orchids, growing in every type of habitat from
tropical rain
forests to the tundra and semi-arid desert, and on every continent
except
Antarctica. Orchids grow in all 50 states, even Alaska!
Since
many homes are quite dry in winter, particularly those with
forced-air heat,
you’ll want to choose species that tolerate such conditions. Not
all orchids grow in rain forests; some
grow in areas with seasonal dry periods.
Some of the more common are found among dendrobiums, oncidiums, and
the
corsage orchid (Cattleya). More uncommon for dry climates
are Brassavola
and some Aerangis orchids. Generally
those that grow best in dry, indoor air include ones with seasonal
growth, hard
leaves, and “pseudobulbs” (a swollen stem area the plant uses for
storage). Using a humidifier near plants, or placing
them on a tray of pebbles, kept moist, will help most any orchid in
dry indoors.
When
buying an orchid, the plant should be securely rooted in the pot and
have
lustrous flowers and firm,
succulent leaves and pseudobulbs. For
those “epiphytes”— that grow naturally on the sides of trees, that
get their
nutrients and moisture from rain and air, which are the ones you’ll
find
growing in bark — fresh, white roots with green root tips also are a
sign of a
healthy plant. As with other flowering
plants, buy orchids with some buds still left to open. Make sure
flowers and leaves don’t have
spots, which could be from poor culture or even disease.
Orchids
are commonly grouped as cool, intermediate, and warm, based on the
plant's
optimum night requirements (45 to 50 degrees F, 55 to 65 degrees F,
and above
65 degrees F, respectively). For warm
homes, consider the Dendrobium, moth orchid (Phalaenopsis),
or Vanda orchids. The moth orchids grow under similar conditions
to African violets, making them one of the best choices for growing
indoors.
Those for intermediate temperatures, such as
Cattleya and its hybrids, may need more humidity to grow well than
is usually
possible indoors. Cymbidum and Oncidium,
while taking cooler temperatures in winter, also need high humidity
and high
light to grow best.
Some orchids may not bloom if the nighttime
and daytime temperatures are the same. Consistently warm
temperatures are good
for leaf growth, but may suppress flower development.
Most
orchids require relatively high light intensities and should be
grown in an
east or south window. However, a few will grow well under low
intensity
fluorescent lights. Insufficient light is the most common reason
orchids don't
flower. If there is too little light, the leaves become a deep, lush
green.
With too much light, the leaves turn yellow-green.
Orchids
vary in their water requirements. The
tropical orchids, which mainly are epiphytes, should be grown in a
very porous
potting medium such as coarse fir bark or lava rock. Place these
pots in the
sink and run lukewarm water through them for about 15 seconds, then
allow to
drain for about 15 minutes. Terrestrial types, rooted in soil,
require a
well-drained growth medium. One of my favorite orchids, which is
easy to
grow in soil indoors in the north and lasts for many years, is the
Jewel orchid
(Ludisia). Another popular
terrestrial orchid, easy to grow indoors, is the lady slipper (Paphiopedilum).
Watering
and fertilizer frequency depends on orchid, and the medium in which
they are
potted. Most orchids growing in bark cannot survive prolonged
drought and
should be watered often. However, some require a "dry season" of six
to eight weeks during which watering is reduced but not stopped.
This "dry
season" must occur immediately after the current growth matures and
is
often necessary to initiate future flowering. Some Dendrobium and
Oncidium
orchid species are in this group.
Orchids
are affected by many of the same pests and diseases as other
houseplants.
Insects such as mealybugs and aphids can be controlled with water
rinses and
insecticidal soaps.
If you want to buy a potted
orchid for yourself or for a gift, check online for local orchid
growers or
societies, or visit your local florist, greenhouse, or garden
store. These can be great sources of information, as
is the American Orchid Society (www.aos.org).
If all this culture sounds too much for you or
your Valentine recipient, consider a cut-flower orchid you can find
at
florists. Protect it from cold on the
way home, and from cold drafts once home.
Keep away from direct sun and heat sources. Cut Cattleya should
last for one week. Phalaenopsis, Oncidium, and Paphipedilum
should last one to two weeks as cut flowers.
Longest lasting orchids as cut flowers, often from 4 to 6 weeks, are
Cymbidium orchids.
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