More orchids are killed by incorrect watering
than by any other reason.The
vast majority of orchids grown by hobby
growers are epiphytes, growing on trees above the
ground where the light is more plentiful. These
are adapted to having their roots exposed
to light and air so in addition to water, orchid
air. The central core of an epiphytic orchid
root is covered with a spongy material called
velamen designed to store water. When this
remains wet too long, the central core
suffocates and begins to rot. Once the roots begin
rot, the plant can no longer take up water
properly and a whole host of problems begin. At
rot will spread upward into the rhizome
the death of the plant. In other cases,
the loss of roots prevents the plant from absorbing
water to maintain the plant in good condition
and the leaves will take on a wrinkled appearance.
The symptoms of over-watering and
under-watering are superficially similar
the tendency is to increase watering rather
the roots. Over-watered roots will be
brown and mushy while those on under-watered plants
will be white or gray and obviously dry.
Orchids should be watered just
as they dry out. This rule applies to all orchids
with slight variations depending on whether your
plant has pseudobulbs (thickened stems that are designed
to store water) or not. Orchids such as cattleyas
and oncidiums should be allowed to just dry completely
between waterings while orchids such as phalaenopsis
and vandas that have no water storage organs should
be watered just before dryness occurs. For vandas,
this may mean daily watering during the warm summer
months. Vandas and ascocendas that are properly watered
will have actively growing root tips at all times.
If the root tips on your plants dry up and seal over,
you are not watering often enough.
There's unfortunately no magic formula;
i.e., water a plant in a 6” pot every 7 days
and you'll be trouble free. This is because your
growing area is different from anyone else's. Humidity,
air movement, potting medium (type and age) and light
levels all play a role. There are several ways to
determine when a potted orchid is almost dry: 1)
the surface of the potting mix will appear dry; 2)
dry pots will feel lighter when lifted; 3) clay pots
feel dry; 4) a wooden stake or skewer inserted into
the potting mix will come out almost dry. If in doubt,
a finger inserted into the potting mix is perhaps
the best tool to determine the moisture content of
the potting mix. It will cause no harm to the plant.
And remember, fresh potting mix will always dry out
faster than the old medium.
How to water?
How to water is just as important to proper culture as when to water. When
orchids are watered, they should be watered copiously. Water should be provided
until it runs freely from the drainage holes. This serves several functions.
First, thorough, copious watering is necessary to soak the potting medium.
In addition, thorough watering helps to flush away the salts that naturally
accumulate in the potting medium from the dissolved salts in our water supplies
and the fertilizers applied for good growth. Also, this is your opportunity
to examine how the potting mix behaves. If you cannot pour water rapidly
through the pot, the potting mix is too dense and you run the risk of starving
the roots for air. If you see finely divided material that looks like coffee
grounds in the water coming from the drainage holes, your potting mix is
breaking down and it's time to repot into fresh medium. At a minimum, try
to thoroughly water your plants at least once a month.
Finally a couple of notes about mounted plants and those like vandas that are
grown in baskets without additional potting medium. First, avoid dunking
these plants in buckets of water. This practice very easily spreads diseases.
If one plant has a disease, all those dunked in the same bucket of water
will have been exposed as well. Also, two short waterings a few minutes apart
are much more effective than one long watering. Once water runs off the plant,
the roots will have absorbed essentially all they can at that time and excess
water simply runs off to the ground. The proper technique is to water your
plants and then a few minutes later water them again, always beginning with
the first plant you watered. This allows time for the roots of the last plant
watered to finish absorbing water before you wet them again. Roots that are
completely saturated will be a solid color while those that are not will