Water culture is something we've been experimenting with since Nov. '95.
The idea is simple. Culturing Orchids in no media except for water. The
water is present all the time. For those wanting to experiment with this
method of Orchid culture, we're presenting a few guidelines to help you.
The container we prefer most is glass though we've even used rubbermaid
containers with as good a success as with glass. The container needs to
be deep enough to accomodate a large root system and the rim of the
container should support the bottom leaves of the plant if possible. For
pseudobulbous plants, a stake can be tied to the plant which will support
it in the container.
Once you've selected which plants(s) you want to grow and the containers
you want to grow them in, consider these basics:
(1) Always use tepid water when initially filling or replacing the water in
your containers. "Tepid" has no discernable temperature. It will feel
neither warm nor cold.
(2) Fertilizer strength and type should be the same as for potted plants.
We keep fertilizer in the water at all times.
(3) Water changes should be done weekly with daily additions if
needed. Do not allow the water level to drop below the top of the roots
for any length of time. So long as the water level is correct, there is
virtually no risk of bacterial or fungal infections. Do not remove the
algae growth from either the roots or the inside of the container. It's
our feeling that it assists with gas exchange within what is basically a
stagnant body of water. At the end of each week just dump the water
(4) Temperature and light is exactly the same for water cultured plants
as it would be if the plants were potted. In other words, follow the same
cultural guidelines for the hybrid or species you're growing. Bear in mind
that the water will quickly reach room temperature. A cold room will stunt
the growth of the plant. A hot room will also stunt the growth of the plant.
65-85 degrees should be the outside ranges of the room with the max in
the 80-85 degree range for intermediate growing Orchids.
(5) "Repotting" is basically not needed until the root system has so
overwhelmed the container that getting the plant out of the container
would cause damage doing so. The roots in these containers will not
rot and only rarely die so expect to see more roots than you're used to
(6) Miscellaneous thoughts: We have yet to have a plant die in our own
experiments. Some plants do seem easier than others though. Phrags
especially seem fond of the method, while Phals, though growing nicely,
seem somewhat slower than pot culture. Cattleyas, Catasetums, Dens,
Mormodes, Oncidiums, Paphs, Zygos ALL do well. Bear in mind that
plants just won't be suitable for this method if they need a rest period.
Give it a try, have fun, and be sure and let us know how things work
out! If you have any specific questions, feel free to email me.
Below are comments by Robert Lin regarding the differences
in water, aerial and media roots. Used with his permission.
Date: Sat, 23 May 1998 19:53:27 -0400
From: Robert Lin
Subject: Re: Roots!
You have asked a very difficult question to answer without
writing a small book. To give you a generic short answer for
others to understand, I must first qualify my statement before I
make it. All of my information is based on other people's
publications. My answer is based on what I've read and the
answer is not exclusively true for all orchids as some have very
different root structures based on their unique development and
First, orchid roots function to uptake water and nutrients,
preserve water loss during drought conditions, and also allows
the exchange of gases to regulate life cycles. Root structures
(i.e., cellular shapes, sizes, types, and the number of cells
from the cortex to the velamen) will vary from species to species
and maybe from plant to plant depending on what and where it is
growing. For this and many other reasons, orchids (and other
plants) are highly adaptive to changing/varying environments.
Many people have reported that orchid roots develop differently
depending on the surface it comes in contact with as it is
growing. Roots can grow fully exposed dangling in the air, in
contact partially on a surface (e.g., bark), and/or growing in a
soil medium. When an aerial root touches a surface, the portion
that comes in contact with the surface will adapt differently so
that the cellular function is optimized for the plant survival.
For example, the area that contacts a piece of bark will often
develop roots hairs on the bottom side, together with smaller
velamen cells and thin walled passage cells. This will help an
orchid cling to the bark and allow better transfer of water and
air on the bottom side as it grows attached. On the exposed
side, passage cells become more lignified or suberized for
protection and reduces water loss in the air. Roots growing in
soil can develop a modified velamen layer but do not always do so
like roots exposed to to the air.
If roots grow into water, they will adapt to regulate water
passage with specialized cell development for a water
environment. Established aerial roots placed into water (as
compared to new roots that grow in water) usually survive and can
adapt because aerial roots have outer cells that are structured
to not allow water freely into the plant (but can still regulate
gas exchange). This allows time (maybe 3-6 months) for an orchid
to readapt and grow water roots in the new water environment.
Some aerial roots will rot soon after being placed into
water but this can be attributed to physical damage that occurred
before being placed in water. A crack along any part of the root
will allow water (and therefore fungus/bacteria) into the
unprotected center of the root and rot occurs. Some aerial roots
just can not adapt to water conditions and die off, but hopefully
new water roots have developed by that time.
In general, water roots, aerial roots (attached and unattached),
and soil roots are different because the roots have developed
differently to optimize and regulate their growing condition.
Orchid roots adapt by developing specialize cells based on the
surface it touches, so each root can be structurally and
functionally different from one another. An orchid will try to
adapt physically, chemically, and biologically to an enviroment
to ultimately produce offsprings.
This article may be reprinted in your society's newsletter if the
following conditions are met:
1) Venger's Orchids must be notified beforehand.
2) Proper credit must be given, with our full web and snailmail
address as follows:
1220 Pando Ave.
Colorado Springs, CO 80906
3) We must receive a copy of the newsletter in which the article
was printed. We collect them :)