The Paphiopedilum
Grower’s Manual
The potting MEDIUM in which you choose to grow your
orchids must be compatible with the conditions under which they are grown.
Your
own growing conditions must be adequately understood before you can choose your
potting soil if you expect to successfully raise your orchid plants. This might require a bit of
experimenting, but then again, it may not. If you have read and understood the chapters on Air and
Light, and Water, this chapter will help you to put all the elements
together into a formula which will suit your own requirements and
conditions. It should not be
difficult; all it really takes is for you to understand how they fit together.
While
there are no ‘magic’ potting mixes, there are some mixes more
suitable than others, especially in particular regions of the world where large
supplies of a particular potting substance are readily available. In the United States there is a good
supply of tree bark preparations, most of which are relatively inexpensive, and
in Southeast Asia and many tropical areas, there is an unlimited supply of
coconut husks. Throughout much of
the sub‑tropical and tropical world there are enormous quantities of rice
hulls, and Canada and Europe have huge stocks of peat moss.
Used
separately, or in combination with other materials, these ingredients form the
bases for countless numbers of potting media combinations used by Paphiopedilum growers to achieve a mix that can work
for them. A mix that is
inexpensive, easy to use, readily available and is long lasting is not
necessarily the one most growers are searching for, even though it may easily
be found within their reach.
The
one in which orchid growers really
are interested, is the potting soil which has to be better than the one they
are currently using. And while
many growers continue to search for one with that ‘magic,’ what
they really want is one that is forgiving.
Ironically,
practically any potting mix can be used with success, for the real
‘magic’ will be found in the techniques and conditions used to cultivate a plant, not in
the mix itself. These techniques and conditions will be
found in the chapters, “When and How to water Your Plants,” and
“Air and Light - The Correct Balance”, and it will be
helpful if they are read first, particularly for growers who have experienced
difficulties with their orchid culture.
Good
success may be had with any material which is locally available, inexpensive,
and which satisfies the basic requirements for a potting soil. But the hardest part for most orchid
growers to understand is this: PRACTICALLY ANY POTTING SOIL WILL WORK WHEN USED
UNDER THE PROPER GROWING CONDITIONS.
This point cannot be expressed too emphatically. (Actually, I have yet to find a Paphiopedilum grower who has found the
‘ideal’ potting mix, except for one; he grew his plants in old,
worn‑out woolen socks, and he swore they never did better.)
Requirements for a
Potting Mix:
Support
Aeration
Moisture retention
Slow decomposition
Low cost
Light weight.
A
potting mix must support the plant in order to prevent its delicate new root
tips from being damaged by movement of the plant in the pot. Each time the plant is irrigated, the
pressure from the water causes movement of the plant. Greenhouse vibrations, brushing past the plant or strong air
movement can also cause it to move and to damage the new root tips.
If
you examine the tip of an actively growing root, you will notice a difference
between it and the root shaft.
Root shafts are rather tough, but even the slightest pressure will
destroy a succulent new root tip.
Damaged root tips will seldom branch or continue to grow; therefore they
must be protected from damage by firmly anchoring the plant.
A
recently divided and repotted plant has only so much energy with which to make
new roots, and if this energy is expended in the continuous making of new root
tips, there will be too few roots which contain the root hairs with which
nutrients can be absorbed. Roots
adhere to the different surfaces of the pots and the potting compound, and it
is through these connections that nutrients can be absorbed.
A
firmly anchored p1ant allows the roots to snake through the potting soil
without damage, and it enables them to produce the maximum root surface
possible during the plant’s time of active growth. Plants with the greatest root surface
areas, and with connections to surfaces, will be the healthiest ones, and such
plant will reward the grower with its best quality and a greater production of
flowers.
All
potting media must allow air to flow through their contents. The more air that is allowed, the
healthier will be the root system.
This translates directly to the overall health and robustness of the
plant. Pots with large drainage
holes, and those shorter pots, often called ‘fern pots’ will
directly influence this capability.
Unlike
Cattleya orchids
which like to get wet and then immediately dry out, Paphiopedilum orchids like some moisture about their
roots almost continuously. Like
cattleyas, they need large volumes of air circulated about their roots at all
times. Paphiopedilums are termed
terrestrial orchids, but this is a somewhat erroneous description. Most paphiopedilums grow on rocks, a
few species even grow on trees and they have their roots embedded in the mosses
or lichens which grow there. Some
may also be found growing upon the ground itself, but a closer examination will
reveal that their roots actually grow into leaf mold and layers of detritus
above the soil level.
Only
occasionally will Paphiopedilum
orchid roots be found buried in the soil.
In habitat they frequently are subjected to long periods of rainfall or
continuous heavy dews, and if their roots were actually in earth, they would
rot from lack of oxygen.
Accordingly, it is important to use a potting mix which retains
moisture, yet one which allows for a sufficient flow of circulating air.
Potting
soils which last for three or four years will allow plants to grow unchecked
and to develop to their full potential.
A soil which breaks down every year not only is expensive in time and
money to replace, but it also prevents a plant from doing well, since it is
always struggling to absorb nutrients from an insufficient root system, caused
by its frequent repotting.
Three
years is normally the maximum time most mixes will remain healthy, but careful
watering techniques and attention to soil‑borne pests can add many months
or even a year or two longer to its useful life. Paphiopedilum
growers living in humid tropical areas will find their potting materials are
very long lasting, since they may only find it necessary to mist their plants
on an occasional basis, and many weeks or months may pass between
irrigations. Growers who maintain
their collections inside a greenhouse will find the opposite is true for them
because of the need for frequent irrigation.
Osmunda fiber is an excellent potting medium,
but not many growers can afford its high price, even if they are able to locate
a source of it. While expensive
potting preparations are often marketed for orchid growing, an equally good and
inexpensive substitute can always be found. If locally available materials are used, meaning essentially
those which do not have excessive transportation or manufacturing costs
included within their price, it will be found that they can offer the most in
economy.
Coconut
palms grow throughout the tropics, and the discarded husks surrounding their
seeds are free for the taking.
Shredded, chipped or pulverized, they make an excellent medium for
growing many kinds of orchids, including paphiopedilums. Sheet moss, bog moss and leaf mulch are
other materials quite suited to Paphiopedilum growing, and sources of them can usually
be found that are low in cost, or even free if you harvest them yourself.
Unfortunately
for those of us who have no access to these materials, we have to pay for our
potting soils. For small
collections, a sack or two of a prepared potting mix, purchased from a local
nursery, is convenient and costs very little. Those with larger collections may realize substantial
savings if they buy their ingredients separately and then mix them
themselves. The cost per pot of
the potting soil really is not much when compared to the cost of the plant
being potted. It only seems so
because it is money that might have been used to purchase another plant.
The
weight of the potting medium in its container must be sufficient to
counter-balance the plant, and to prevent it from being tipped over. However, neither the pot nor the
potting compound should be so heavy that undue stress is placed upon greenhouse
benches. Consideration should also
be given the fact that plants are frequently repositioned within the growing
area, and carrying unneeded weight can become quite a chore for a grower.
Bench
construction costs can also be reduced simply by the use of potting soils which
utilize organic materials, rather than those with sand, gravel or rocks, which
require sturdier construction.
Remember that certain potting soils may be light in weight when dry, but
become much heavier when watered because of their moisture retaining
properties. These effects should
be considered when choosing your potting media.
Fir
bark is a collective term that lumps together all types of tree bark
preparations. Initially, fir was
the predominant species of bark supplied for potting orchids, but one must now
expect any of a dozen or more different species of wood to be packaged inside a
sack of ‘fir bark.’
While fir bark is probably the most widely used potting medium in the
United States, care must be exercised when purchasing it for your orchids.
Before
buying a sack of bark, you should examine the contents for ‘fines’
(those dusty wood particles and the too-small particles for that grade of bark)
and for its general quality. Some
brands have better quality control than others, but there can be considerable
differences from season to season, or even from sack to sack within the same
brand.
Good
quality bark should be hard, not soft and spongy. It should flake not crumble or compress, and it should be
dry with no signs of mold or decomposition. If you find a supply of good bark, buy as many bags of the
same kind as you are able to store properly, because the next time you try to
find the same bark, you won’t!
Sunlight causes the plastic bags in which fir bark is packaged to
disintegrate, so keep them out of the sun. Also, most of the sacks have air holes to let the bark
‘breathe,’ and they must not be stored where they can get wet.
Fir
bark comes in several sizes or grades, from ‘seedling’ size, to
‘large’ size.
Medium-grade fir bark has particles measuring from one‑half inch
to three‑quarters inch, and is commonly used separately to pot mature
paphiopedilums. Seedling-grade
bark has particles from one‑quarter inch to three‑eighths inch and
is used to pot both seedling and mature plants. Large-sized Paphiopedilum plants can be successfully potted in a
half‑and‑half mixture of both medium-grade and large-grade fir
bark.
All
grades of fir bark are generally available, at least for the present time, with
only some seasonal shortages in their supply. Besides being inexpensive, bark fills the five basic
requirements for potting soils very well, and the ease of handling is one of
the better reasons for using it.
To
prepare fir bark for use, place the required amount into a large bucket, a tub
or similar container, and fill it with water until the bark floats freely. There should be enough water to allow
you to mix it thoroughly from bottom to top, using a large stick or paddle
until all the bark is thoroughly wetted.
Let
the bark stand for an hour and then stir it again, thoroughly and vigorously,
for a few minutes. It should then
be left to stand for about a day, or at least overnight. You should vigorously stir the bark
again, and all the good bark will be found floating at the top and all the soft
and spongy fines will have sunk to the bottom. The good bark can be lifted out of the container and used,
while the remaining residues and the water can be discarded.
When
the surfaces of the bark have dried so they are no longer wet, but are still
moist, the bark is ready to use.
Not only will this treated bark cause fewer splinters in your fingers,
but also its pre-soaked conditioning will enable it to retain more moisture
during the first several weeks or so.
This
conditioning of the bark is important because it will provide humidity for the
needs of newly potted plants during the time when they need it the most. Dry fir bark used without this
preparation wets very slowly, and it may be weeks before it becomes conditioned.
Redwood
bark has also been used as a potting medium for Paphiopedilum orchids, but its use is not
widespread. It is not easy to find
now and some species of paphiopedilums even grow poorly in it. It has a low pH and is best used where
water supplies are slightly alkaline, since problems of excessive acidity can
result when it is used in regions with acidic water sources.
Redwood
bark lasts for many seasons and its moisture retention properties are
excellent. It inhibits the growth
of certain molds and bacteria, but seems to promote the growth of others. It is available in several grades,
including a ‘wool’. A
major drawback to its use is from the numbers of tiny, very irritating splinters
one gets in his hands and fingers when potting with redwood, and there does not
seem to be an easy way of eliminating this problem.
The
low pH of redwood can be an issue, since redwood cannot be used successfully
with all species or in all parts of the country. Mixes made by combining both fir bark and redwood bark, have
usually been proven unsatisfactory since fir bark decomposes faster than
redwood. Also, this combination
seems to promote the growth of certain fungi, which hasten that decomposition.
Osmunda fiber comes from the root ball of two or three species of
ferns. It is produced in both soft
and hard textures; the former being derived from the smaller roots at the
perimeter of the root ball and the latter comes from the heavier bases of those
same roots. Paphiopedilum growers prefer the softer fiber for most
of their species, while some larger species are more adaptable to the coarser
fiber. Both fibers can last for
many years.
Plants
potted in Osmunda may
be successfully ‘potted on’ to the next pot size, without the need
to remove any of the old fiber, which will cause damage by disturbing the root
system. This is a major advantage
over other types of potting media since it allows the plant to attain specimen
size without being setback by repotting.
Unlike
fir bark, which consumes nitrogen during its decomposition and thereby robbing
the plant of needed nutrients, Osmunda fiber produces nitrogen that becomes immediately available
to the plant. Osmunda also retains moisture well without
becoming too wet. It is light in
weight and it offers good support for plants. Unfortunately, it has a serious drawback, which is the great
difficulty experienced when the plant is divided.
Osmunda fibers are like a net, with each fiber
being connected to the next, therefore each orchid root must be individually
removed from it whenever the Osmunda needs to be replaced.
The orchid's root hairs attach themselves tenaciously to each particle
of the fibrous root and by the time an orchid has been divided and cleaned of
old Osmunda fiber, it
will have few if any, surviving roots.
One
solution to this problem is to cut through the root ball with clippers and to
‘pot-on’ each division of the plant. If care is exercised in the selection of plants potted in Osmunda fiber, and if every plant grown in it is
intended to attain specimen size, then the problem will only be faced
occasionally.
When
the demand for Osmunda
was small there were adequate supplies of it for both the domestic and foreign
markets, but during the 1960s the numbers of orchid growers increased
dramatically and the supply soon fell far short of demand. The price has continued to rise now, to
about ten times that of a bag of fir bark. Availability is very limited at present.
Peat
moss, sheet moss and bog moss are three types of mosses used in the
culture of orchids. Each has a
different application. Peat
moss, which is bog moss
after it has been dried and pulverized, has excellent water retention
properties. It helps to control
and to restrict the growth of fungi because of its low pH property, and it is
used in fine‑textured potting soils.
Sheet
moss grows on rocks or
trees and comes packaged dry in bales.
Cut, chopped or torn into pieces, it is incorporated into mixes using
fir bark and sand. Its main benefits
are in its water retention properties and its ability to keep the mix more
open. It also helps to control and
to restrict the growth of fungi, because its low pH is not a suitable
environment for them to survive.
It is commonly used for mounting orchids on slabs, or for those placed
on tree limbs, since the moisture retention capabilities provide humidity
necessary for an orchid’s needs during re-establishment.
Bog
moss is living moss, and
is gathered in sheets or clumps.
It is used as a single ingredient for potting many different species of
orchids in much the same way Osmunda fiber is used.
Its advantages are in the ease with which it can be potted, its salt‑free
nature and its long life. Bog moss
may be kept alive and serviceable for years if it is watered with pure water or
rainwater instead of tap water, which contains chlorine. An added bonus is that it can be
collected for free if you live in those regions where it grows, or at least
until it becomes an ‘endangered’ species.
Growers
with reverse osmosis, de‑ionized water systems, or those who collect
rainwater for their irrigation, will have less difficulty keeping all mosses
healthy, since they are able to water the special bog-moss containing pots
along with the rest of their collection.
A grower forced to hand-water certain plants with a bottle of distilled
water, when he normally waters his collection with the garden hose, might find
that potting a few plants in bog moss is burdensome.
But
bog moss can be extremely useful when sickly plants, or tiny divisions of rare
species are potted in it. This
treatment will bring about a miraculous recovery of most plants whose vitality
is in decline, and for this reason alone bog moss can prove its worth.
It
should be noted, that in order to keep the living moss alive and healthy for
long periods of time, it should be potted in white pots, which allow what seems
to be the right amount of sunlight to penetrate through the sides of the
pot. Clear pots can allow algae to
grow, which may then suffocate the living bog moss, and if black, or darker
colored pots are used, only the moss at the top of the pot will remain green
and in active growth, while the remaining moss inside the pot will
eventually cease growing and then die.
New Zealand moss is a dried bog moss,
but it does not retain the same properties as when it is alive. It shows no particular benefit over any
other type of dried moss, and its loose texture makes it less adaptable for
mounting orchids than sheet mosses do.
When chopped and used as an ingredient in potting mixes it seems to
perform well, but in the U. S. the added cost of freight hardly seems to
justify its use.
Fallen
leaves from any kind of plant, which have dried thoroughly but have not
decomposed too greatly, constitute ‘leaf mulch’. Some leaf mulches are better than
others, for different reasons and uses, depending upon the species of plant
from which they originated. Used
separately, leaf mulch seldom performs satisfactorily for Paphiopedilum growers, yet when combined with other
ingredients it seems to possess limited benefits.
When
selecting leaf mulch for use in a Paphiopedilum mix, choose one that breaks down slowly,
and one which matches the decomposition rate of the other ingredients in the
mix. The leaves should be reduced
and screened to a uniform size, so as to not cause either the water or air to
be restricted.
Of
course, some species of paphiopedilums grow in leaf mulch in habitat, but since
together, their other habitat conditions are nearly impossible to duplicate in
a hobbyist's greenhouse, caution is required for its use. Leaf mulches are still in an
experimental stage and should be used with this in mind.
Inorganic
potting mixes arouse renewed interest from time to time, especially amongst
newer hobbyists who are searching for a method to address their unsuccessful
growing techniques. Volcanic
rock, vermiculite, Aliflor, sponge rock, gravel, sand and different forms of
plastic or clay materials are some of the more frequently used substitutes for
common orchid mixes. One reason
for trying any of these items is that they can be used over and over again;
they never decompose. Realistically
though, few are ever used a second time.
For those that are recycled, unless they are sterilized with bleach, and
then very carefully and thoroughly rinsed in a neutralizing acid-water bath,
the chance of transferring harmful soil contaminants to a new mix is very
great.
Each
substance however, seems to have a number of disadvantages, which usually
become greater than the single advantage of its durability. Gravel, and most forms of plastic do
not retain moisture, while other substances retain too much. Some are too heavy while others are too
light. If the advantages were
really worthwhile, the inorganic mixes would have found a greater acceptance
than they have. I never found a
good use for any of them except for sand, which I use in combination with fir
bark and sheet moss.
Charcoal
should probably be included in the inorganic category since its properties
closely resemble those of that group.
It has been used for many years and by a great many people, most of whom
believe that charcoal has some sort of ‘magical’ properties. It has none in fact, other than the
fact that it lasts for a very long time, and it has the same problems with
reuse as have all inorganic components.
I cannot
recommend the use of charcoal for an orchid potting ingredient simply for
the fact that charcoal comes from the destruction of hardwood trees. Very little of it is produced in the
developed countries; most of it comes from what we like to call the ‘rain
forests.’ Since there are
numerous other substances which can be successfully used as a replacement, I
see no good reason to include its use in our list of potting ingredients.
Coconut
husks are the thick, fibrous covering that encases the hard‑shelled
coconut seed found in most produce markets. It is a universal potting medium, used throughout the tropic
and sub-tropic areas for orchid culture, and it seems to be an ideal substance
for that purpose. With the hard
shell of the seed removed, the remaining husk-half is frequently used, in which
is placed an orchid plant, of practically any species, and they can be seen
hanging from fences, windows or from small trees in the yards of many native
residents. Shredded or chopped,
the husk retains moisture well without becoming too soggy, and even when
subjected to continual rainfall for extended periods, it does not become
waterlogged when used as a potting medium in either pots or in baskets.
Roots
cannot penetrate deeply into large pieces of the husk unless it is loosely
shredded or chopped, and growers from light rainfall regions will pot their
plants in that grade of the coconut husk.
In high rainfall areas, those larger chunks of husk are used to allow
for more air circulation, and to prevent roots from rotting by the retention of
too much moisture. The particular
benefits of coconut fiber are in its lasting qualities and in its light
weight.
There
is a problem with some sources of coconut fiber, which is caused by the high
concentrations of salt which it can contain. A thorough soaking, in large quantities of two or three
changes of fresh water, will leach out the salt and it will also serve to
settle out the fines, as is done with fir bark. Another problem found with the use of coconut husks is when
they are crushed, rather than cut into small particle sizes. This crushing causes the particles to
expand, therefore it allows them to absorb and to hold more water, which then
leads to their more rapid decomposition in use. For best results, look for small particles which are firm, not
spongy.
Once
a plant is placed in coconut husks it can be left for a long time, allowing it
to reach its fullest potential in both flower production and plant growth. Frequently, orchids potted in wooden
baskets, or even those in clay or plastic pots using coconut husks, can easily
be potted-on instead of being repotted, particularly if larger chunks of it are
used. Coconut husks are readily
available since they are discarded when the coconut is harvested, and they are
found in large waste piles where coconuts are grown, frequently near the sea.
There
does not seem to be any serious disadvantages to using it as a potting
substance in those areas, but coconut husks do not perform quite as well in a
greenhouse. This problem may have
more to do with our watering techniques and our unfamiliarity with it as a
growing medium. More recent uses
of finely ground coconut husks as a substitute for peat moss have found some
successes, particularly when used as an ingredient for terrestrial orchids.
I
suspect that because of the rather unstable quality found in fir bark, as well
as the uncertain future of its supply, coconut husks will become the more
commonly used potting medium in the future. In fact, by utilizing the different grades in a mix, it
might even be used as a single ingredient potting medium with most satisfactory
results.
When
incorporated with other ingredients, rice hulls can be part of a good potting
mix for Paphiopedilum
orchids. A mix of rice hulls, loam
and decomposed chicken manure produces some excellently grown plants, and it is
frequently used in regions where rice is grown. The hulls are slow to decompose, they aerate the mix well
and they are free.
Unfortunately,
when used alone, the hulls tend to pack firmly together, which prevents the
free passage of air and water.
Different proportions should be experimented with to find the most
workable ratio of hulls to other equally long-lasting ingredients. Keep in mind, that while rice hulls are
long lasting, they then break down rapidly and attention must be paid to this
factor.
It
is widely thought that Paphiopedilum orchids need limestone, or extra calcium added to their
potting mix, since many species are found growing on limestone in their
habitats. However, not all plants
of the same species are found growing only on limestone. The fact that some do grow on limestone
has nothing to do with their calcareous nutritional requirements; it simply
means that the pads of mosses found growing on the limestone rocks are where
their seeds will both germinate and then continue to grow. It probably has more to do with the
presence of Mycorrhiza,
which provide the conditions which allow the germination of their seeds to
occur, than for any other factor.
Limestone
is cold‑water soluble and many, but not all of those species of
paphiopedilums found growing on it are from warmer climates. There can only be minute traces of
calcium made available to these plants, which would be equal to the amount
found in almost any public water supply.
Putting extra calcium into a potting mix probably will not do them any
harm, but it won’t do much good either. Keep in mind, that by adding certain forms of calcium to
your potting mix it can turn the soil pH more alkaline.
Combination
mixes are widely used, usually because many growers feel the addition of
several ingredients will provide nutrients necessary for the plant's continued
good health. Even though no one
knows what Paphiopedilum
orchids require nutritionally, most people believe it necessary to use a
potting soil which has a number of different ingredients, simply to provide for
whatever the orchid plants could need.
Most
potting media actually provide little nourishment for plants potted in them,
and in fact, fir bark and other wood preparations actually use nitrogen as they
decompose. As soon as any free
nitrogen is generated in the pot, the microbes attacking the decomposing fir
bark will consume it before the orchid does.
The
main benefits of combination mixes are in their properties of water retention
and aeration. Vermiculite,
volcanic rock, sponge rock and other inorganic substances frequently hold
either too much water, or not enough.
But used in the proper ratio and with other compatible ingredients, they
can be effective. While you may
wish to experiment in this area, a more effective method is to find someone who
is having good success with his potting mix, and then experiment with a small
amount of it in your own growing area.
Keep in mind also, that you must both have similar growing conditions
and techniques.
The
most successful potting mix I have used, is one made with chopped sheet
moss, medium-grade fir bark and either river sand, sometimes called
‘plaster’ sand, or silica sand of about 16 mesh. I mix it by volume, and do so according
to the species of plant to be potted.
I vary the amounts of the ingredients according to the basic growing
conditions of each species in its habitat.
For
those species which grow with their roots embedded in mosses, I may use moss at
about one‑third by volume.
For species which grow more terrestrially in leaf mold and forest
detritus, I may reduce that amount to one‑sixth, and then add more
sand. Another factor to consider
is the amount of rainfall each species receives. Those from very wet climates will need more moss added to
their potting medium.
For
most Paphiopedilum
species, I make a mix using the following ratios:
‘A Pretty Good
Mix’– (by volume):
8
parts - medium grade fir bark
2
parts - chopped moss, (compressed)
1
part - washed river sand
If
both the fir bark and sheet moss have been conditioned by pre-soaking with
water, (to eliminate the dust in the moss) and the moss is squeezed to a
‘just damp’ state after chopping, it is much easier to pot with
than when either is dry. This
combination mix is difficult to use if it is too wet, since it tends to adhere
to your hands and fingers.
Plants
potted in it should be potted firmly, using finger pressure and not a potting
stick. While this particular
combination mix has proven very successful for Paphiopedilum orchids, I have also had great success
using it with many other types of both terrestrial orchids and epiphytes. Its advantages seem to outweigh the
bother of having to chop up the moss, and, I can recommend its use.
Since
mosses of the various types have such ability to retain moisture without being
waterlogged, they are an excellent choice for use in orchid culture. Because the moss is so fibrous, it
allows for very good air circulation within the pot, which is something that
all orchids require. Mosses
duplicate many of those conditions found in the plant's natural habitat, in
respect to pH in particular. In
addition, its lower pH prohibits the growth of many fungi, which will then
increase the longevity of the potting mix itself.
When
the fir bark in this combination mix decomposes to the point of collapse or
disintegration, the fibrous moss prevents the accumulation of muck at the bottom
of the pot, and it delays or even prevents the roots from rotting. This is a very ‘forgiving’
potting mix, as it allows plants potted in it to remain in relative good health
well beyond the point where other mixes would have become toxic.
For
growers who are unable to water their plants frequently,
this combination mix retains sufficient quantities of moisture in the pot,
which can ensure the plant's good health.
Conversely, one of the best advantages of using this potting mix, if the
plants placed in it are properly potted, (meaning firmly), is that it cannot be
over-watered.
It
is doubtful the sand provides any nutrient value to Paphiopedilum orchids, but because of their small
particle size, the grains of sand provide countless surfaces for the
evaporation of the irrigation water.
(This is another reason why the mix cannot be over-watered.) Another benefit of their use is the
fact that root hairs frequently attach themselves to the particles of sand.
When
repotting Paphiopedilum
orchids that have been previously potted in this combination, I have observed
that this mix is very slow to decompose.
Many plants potted in it for five, or even six years have shown no ill
effects, even though the mix has begun to break down. Several plants potted in it for almost ten years (this is NOT
recommended) showed signs of poor health, but they had continued to make new
roots, even though most of the older ones had rotted.
Root
hairs also attach themselves to the moss and the fir bark in this mix. Besides providing an anchor, root hairs
usually attach to those places which can provide some means of obtaining
nutrition. It would appear then,
if root hairs attach themselves to particular ingredient in the mix, it is
probably serving a useful purpose and should be retained in the mix. Conversely, those ingredients which do
not attract root hairs probably are not serving a useful purpose and might just
as well be eliminated the next time you mix up a batch of potting soil.
Another
observation, and probably one of the most important reasons for my suggestion
for potting Paphiopedilum
plants in a mix using these three items, is the fact that it is almost
impossible to kill a plant that has been potted in it. Whether or not it is because these
plants remain healthier and can resist attack more readily, or because the moss
in the mix prevents the growth of many fungi, (as would be the case with most
other media), is not known. I
suspect that, in addition to these reasons, the single most important element
of this mix is the fact that it can allow a large volume of air to circulate
through it while still maintaining sufficient moisture about the roots. Whatever the reasons, the fact of its
success has been readily apparent.
If
you have been having trouble with your potting media, perhaps you can improve
your successes with a mix of this type.
While it is not ‘the magic mix’, it is a forgiving
mix, and if you are somewhat lacking in your other skills of plant care, this
type of combination mix can help you to improve your success.
AN
IMPORTANT POINT TO REMEMBER: Paphiopedilums will grow in a wide variety of
substances, but the trick to easy growing is to find a mix which both they, and
you will like, and then stick with it. If you find yourself continuously changing your potting
mixes, trying to find one that works best for you, it would be a good time to
re-read the other chapters in this book about air movement, light and watering
techniques. It is these three
elements, which have a more influential effect upon your success or failure,
rather than your potting mix.