Most orchids live in or on a potting medium made of bark instead of soil, so they must
be watered differently than most houseplants.
How to Water Orchids Grown in Sphagnum Moss
Some orchids are grown in sphagnum moss. You can water these from the top, the
way you water other plants. But be aware that sometimes moss can feel dry on top
but it’s still wet inside. Insert your finger up to the first knuckle inside the moss to
determine if it’s actually dry.
Sphagnum moss holds water pretty efficiently, so beware, especially if the orchid is
also in a water-retaining plastic or glass pot. Orchid roots need air to grow. Too much
water displaces all the air, thus rotting your orchid’s roots.
How to water orchids grown in bark
When watering orchids, the goal is to saturate the bark pieces, not the roots
themselves. Always use room temperature water — not cold, not hot. Avoid letting
water stay inside the places where leaves meet the stems of an orchid; this promotes
rot
The best way to water orchids is to place the entire pot into a bowl that’s at least as
deep as the bark line. Pour room temperature water over the bark to just below the lip
of the pot and let the bark soak for 10 to 15 minutes. If you put water in the bowl first,
you’re apt to push the bark out of the pot when you sink it into the water!
Then, lift the pot out of the water, let all of the excess water drain out, and place the
orchid back in bright but indirect light.
Clay pots are great vessels for orchid plants because the terra-cotta also absorbs
moisture, offering the orchid a little more humidity and water when the bark dries out.
How Often Should You Water Orchids?
Watering orchids is more of an art than a science. How often to water depends on a
number of factors, including how warm it is, how much light the orchid gets, what type
of orchid you have, and what type of potting medium the orchid is growing in.
A general rule of thumb is to water once a week for drought-tolerant types of orchids
such as cattleyas, oncidiums, dendrobiums, and once every four or five days for
others such as phalaenopsis.
All orchid mixes should be moistened thoroughly each time you water, then allowed
to dry out before watering again.
Misting Orchids
Misting by hand does not need to be part of your orchid care. The idea is to raise the
humidity, but you can do this more efficiently by placing orchid pots on top of a layer
of rocks that are sitting in water. You don’t want the water constantly touching the
bottom of the pot; you just want the evaporation of the water to humidify the plant.
You also can help your orchids by running a humidifier in the room where they live.
Adding Fertilizer to Water
Many orchids bloom with no fertilizer. If you choose a liquid fertilizer, use it at half
strength every other time you water. More fertilizer is not better. It’s best to stop
fertilizing when the plant is dormant, usually during the winter. Give plants a month or
two without fertilizer. When temperatures rise and day length gets longer, begin
fertilizing again.
Orchids perform well with a balanced formula of fertilizer (such as 10-10-10) or a
fertilizer especially formulated to stimulate blooms, with a high middle number such
as 11-35-15.
Always use a water-soluble fertilizer. Granular or stick types of fertilizers don’t work
well because, unlike how they perform in soil, they can wash out before getting a
chance to interact with the bark mix.
Factors That AÙect Watering
Potting media – Different potting media retain different amounts of water.
Pine bark nuggets will hold a water longer than charcoal or clay pellets. The
greater the water retention, the less you need to water. Mounted plants will
need more water.
Species – Make sure you are familiar with your particular species and
following its rules. Different orchids can have very different watering
requirements, and it can be very challenging to have a mixed collection without
overwatering or underwatering at least some of your plants. I’d start with just
one or two favorite varieties.
Temperature – The higher the temperature, the greater the need for water, in
general.
Humidity – In general, the greater the ambient humidity, the less need for
watering. Humidity is closely related to what kind of potting media you are
using. Many home-growers keep their pots in a tray of pebbles filled with water
to increase local humidity.
Air flow – Don’t be afraid of a little air flow. Orchids like plenty of fresh air, both
around the roots (for mounted plants) and leaves. But greater airflow tends to
dry them out quicker, so you’ll need to increase watering.
Source: www.bhg.com
