PAPHIOPEDILUM (the Slipper Orchid)
More than 60 species of Paphiopedilum
(pronounced paf-ee-oh-ped-i-lum) are found in
nature from the high hills of northern India to
the lowlands of the Philippines and New Guinea.
They are magnificent orchids and both the
species and the hybrids have always formed a
major part of good collections.
They have a fascinating array of colours and
forms and their ease of culture has attracted
lifelong admirers.
All Paphiopedilum are characterised by
both a cup-like lip called the pouch, which
gives them the common name of lady slipper, and
a prominent dorsal sepal.
The plants are mostly terrestrials, although
some, like Paphiopedilum lowii may be found
growing epiphytically, (on trees) or
lithophytically, (on rocks) They are dwarf to
moderate sized with leaves that are stiff, waxy
or leathery and range from a glossy green to
beautifully mottled. The leaves usually form a
fan-shaped tuft.
An erect stem, bearing one or more flowers,
arises from the centre of each new growth.
Some species e.g. P stonei and P
rothschildianurn, may produce up to six flowers
on eachstem. The flowers are from 2" to 5W'
across in a variety and mixture of colours and
may last perfectly on the plant for six weeks or
more.
The major blooming season is from mid-autumn
onwards although variations occur.
Paphiopedilum are divided into two cultural
groups: the warm-growing, mottled-leaved types
like the famous Paphiopedilum Maudiae (ideal for
beginners), and the cool growing, plain-green
leaved types. All types require reasonably cool
nights, particularly in the spring when they
will be setting their buds for the autumn
flowering season. Although this need makes them
difficult to manage in warm areas, their low
light requirement makes it possible to keep them
cool by shading. Hence, both mottled and
green-leaved Paphiopedilum may be grown
side-by-side but perhaps not to the same
perfection as if their requirements were
tailor-made.
Temperature and Humidity
Green-leaved types ideally require a minimum
night temperature of approx. 55°F while the
mottled- leaved types do better with a night
temperature of 60-65T. Day temperatures should
range between 70-80°F although short periods of
higher temperatures will not injure the plant.
The humidity should be moderate, between 50-60%
during the day. Light Paphiopedilum enjoy medium
light intensity, about 800-1000 foot candles
throughout the year for optimal growth. Avoid
direct sun, except in the early morning. In the
house, move plants back from the window at the
height of the midday sun or, ideally, grow them
behind a shade curtain. Air Movement Moist air
and vigorous air movement at a favourable
temperature, is highly recommended to keep the
leaves cool and to dry drops of water on the
plants thereby reducing the chance of spreading
disease. Hot or cold draughts cause bud-blast
(the buds turn brown and die).
Watering
Paphiopedilums do not have pseudobulbs and
so, like Phalaenopsis, they must have a regular
and constant water supply. This entails keeping
the growing compost moist but not wet, a
technique that beginners will have to practice
to get perfect. Water the plants early in the
day so that the foliage will be dry before the
temperatures drop at nightfall. Plants typically
need to be watered every five to seven days but
weather conditions may modify this need. The
potting medium, the surrounding humidity and the
weather all affect the rate at which plants dry
and thus need water. For those growers using
bark as a potting medium, it is essential not to
let the plant dry out completely because bark
becomes very difficult to re-wet. Water will
channel through the dry medium without wetting
the plant or the compost. If this happens
submerge the whole pot in a pan of water until
moistness and wettability have been restored.
Fertilising
Plants growing in bark need a high nitrogen
fertiliser (30-10-20 or 30-10-10 ratio) at half
the strength recommended on the pack. Fertilise
greenhouse-grown plants three times in
succession and the fourth time, flush through
with pure water to leach out any mineral salts
that have accumulated. For home or windowsill
growing, alternate the fertiliser with a pure
water flush. Plants grown in some of the more
complicated mixes with leaf mould and peat
should receive fertiliser at more reduced
strength because the mix itself provides
nutrition and extra nitrogen may cause souring
of the compost.
Potting
Because most Paphiopedilums are terrestrial a
medium that drains well but retains moisture is
needed. Four parts fir bark to one part Perlite
is excellent. Finely chopped fir bark (l/8th to
1/4 inch) is preferable to the medium or large
chunks used for Cattleya and Cymbidium. Moisten
the bark mix thoroughly before potting any type
of orchid in it. Paphiopedilum can easily grow
into specimen plants because, with good culture,
they will produce growths freely and regularly.
They are capable of producing flowers on
rootless growths and in such cases particular
care must be taken to ensure that large plants
have good, supporting root systems. Repot
Paphiopedilum before the growing medium
decomposes and before the plant has outgrown its
pot, or when it needs dividing (i.e. about once
each year). The repotting procedures entails
first, clipping off dead roots, then positioning
the plant in the new container and finally
filling in around the roots with the compost
medium until it reaches slightly over the base
of the plant. Do not bury the new plant growths
as this will cause rotting. The base of each
growth should be in contact with the growing
medium to encourage new roots to form. Restrain
watering to a minimum until evidence of new
growth is apparent but do not neglect the
humidity or the plants will dehydrate. Recently
repotted Paphiopedilum should be placed in a
shady area and moved gradually into the correct
light conditions once new growth begins.
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