From: "Dawber, Ken" Ken.Dawber at getronics.com> on 2002.06.28 at 08:54:55(9035)|
Low Maintenance Indoor plants Emersed in
For the last couple of years I have had an interest
in low maintenance indoor plants growing emersed in water. This interest
came about due to my disgust at the large number of people who have given up on
using living breathing plants and gone over to the pretend plastic
etc. My objective was to create indoor living plant displays that
would survive the non green thumb.
Yes, you too can have live indoor plants … and a
life. Come home after a month or so away and find the indoor
plants alive without having had other people enter your house. No concerns
about killing plants by over watering. When a big glass jar is low on
water its very obvious.
For information relating to indoor air quality and
indoor plants see http://www.oxford.net/~steve/sick.htm#SickInteriorEnvironments
Note that many of best plants (from the NASA study)
for cleaning air are Aroids.
I have spent a lot of time researching (internet
etc) other peoples experiences with keeping indoor plants with the roots kept
emersed in water. I have found it very hard to get reliable
information. Much of the information I have gleaned I am placing below for
comment. I am not qualified in Horticulture and much of the information I
have picked up is from people who have even less knowledge. I welcome
criticism as well as wanting more information
My interest was to keep the plants with the roots
emersed in just water in a jar (generally a glass vase). In some cases I
include a layer of pretty stones at the bottom. There are similar concepts
that are often labeled water culture where the roots stay immersed in water plus
an inert medium. I expect most of the concepts to be the same but with the
inert material you don't get to see the roots and they don't show the level of
water as easy unless they have a water level indicator added to
The last of the 3 links above on air quality is a
site with a lot of information on this water plus inert material type of hydro
First my objectives needs to be
1) A healthy looking display. I do not
have the objective for the plant to grow as in expand in size. Considering
the costs of good glass vases it's often an advantage if it just grows very
slowly.2) Lack of need of expertise once set up. 3) As
close to zero work as possible once set up4) They must survive in low
light conditions (ie indoors)5) Plants that are known to survive
gas-heating, air conditioning and similar.
Some of these objectives require me to look at
terrestrial plants that most would not think of as water plants.
Things I have found are as follows:
A) Plants that can survive with their roots
emersed are called Hydrophytes. Some Terrestrial plants are hydrophytes,
others aren't. The most common methods for plants to acclimatize to root
emersion is to either change the roots to being aerenchymous or grow new roots
that are aerenchymous. These are roots that have air channels in them that
bring Oxygen etc from above the water line down to the root systems.
Doing a search on the internet for the word aerenchymous will show a lot of
detailed information on this.
In the way that
I am setting up the plants the water is still. I believe that the
water should be thought of as anaerobic (that is, without oxygen).
Some plants are better at acclimatizing than
others. One study of a plant (Rumex Spp.) that could acclimatize showed
that plants of this species that came from low-lying areas did a better job
(i.e. grew longer aerenchymous roots ) of acclimatizing than those of the same
species that came from drier habitats.
B) Just because a plant is known to get root
rot in wet soil doesn't mean that it will get root rot when the roots are
emmersed in water without soil. I often get told by a nursery that such
and such a plant will rot in wet soil yet when I ignore that advice I find no
problems in keeping it in water. Of course I would only do this if I knew
that it was one of the plants that gets mentioned as a plant to keep in water or
closely related to one. A couple of possible reasons why they don't get
root rot (ie theories of mine but I'm not exactly expert enough to know if
I'm correct) are as follows:
Theory OneRoot rot is caused by various soil
born fungus (In some places it gets defined as "soil born") While
these organisms love a wet environment maybe they still require soil.
Theory TwoWith clean roots inside a glass jar
with this inside a house or office, maybe the water and roots never gets
infected with any spores to start the root rot attack
A corollary to this is the advice that you will
probably get better results if the environment has no soil. I try to clean
the roots as best I can before putting them in the vase or jar.
Going by much of the literature on hydroponics etc
it would seem that the lack of soil will also be advantageous in stopping a
whole host of other problems that are common with normal soil based
By the way, I'm not saying that it can't get root
rot or vice versa. This is something I would like to know. Just that
many of the plants that are known to survive in clean water are plants that are
known to get root rot in wet soil.
It is also interesting that in the aquarium
literature several truly aquatic (ie. Used in aquariums ) aroids are susceptible
to something called root rot. This occurs in most species of Cryptocoryne
and some Acorus. In Cryptocoryne it is caused by incorrect water chemistry
(particulary iron and CO2) or sudden changes in water chemistry. I
would expect that regardless of the name and appearance of this being called
root rot, it probably is totally different in concept and cause to the soil born
fungus root rot in normal soil agriculture.
Anyway, the problem generally isn't so much root
rot but the ability of the plant to survive without the roots getting oxygen.
It is this that generally differentiates what I am
doing from hydroponics and similar. With almost all hydroponics the water
is cycled on and off so that plants get plenty of air on the roots. I'm
just dropping the roots in water and leaving them there
I often leave the water levels to go down nearly to
the bottom before refilling (ie over a month or so) I expect that the
plants getting air on some of the roots for various periods would be
beneficial. This is meant to imitate a plant going through various levels
One thing I do not know is how to tell if a plant
dies due to lack of oxygen to the roots or due to some other cause. Can
anyone tell me if there are any specific symptoms associated with lack of oxygen
to the roots?
C) In converting to water most people who
succeed seem to cut the roots back. (A heavy trim)
D) Those that succeed either do not fertilize
or fertilize with a minute fraction of what you would expect. My
initial theory as to why this was so is that these terrestrial plants only
become hydrophytes as a means to survive floods. In this situation that
are not in their optimum growing situation. It's a bit like winter when
you feed less, only more so. In this situation plants don't seem to like
more fertilizer than they need. If this is true then a problem that this
implies it that most plants won't flower in this situation so you have to chose
plants that look attractive without flowers /inflorescence. Most of
my water culture plants were picked for their leaves rather than there
A problem with the above theory is that some of my
plants have lush growth. This includes ones that have roots emersed
without ever having any added fertilizer.
The second possible reason for this is that when
you put fertilizer on a plant in soil, most of it washes through or remains in
the soil. Only a small proportion gets caught by the plant roots in the
soil. When you put fertilizer in the water of the emersed plant, the
fertilizer remains there.
The aspect of what mix to use for plant food is
something that I need more information on. There is a reasonable amount of
information on feeding of aquarium plants, some of which probably applies but
other information that doesn't apply. In the aquarium situation the fish
droppings (after processing by bacteria), excess food and filter residues give
the plants plenty of Nitrates and Phosphates. The special aquarium plant
foods are designed around this, and probably would not be suited to a root
emersed plant without fish.
I expect that when the terrestrial plants are in
their hydrophyte mode that the relative quantities of the different components
would be different to normal. I don't know which elements they need less
of and which they need more of so at present I am just giving some of them a few
standard slow release fertilizer pallets and other's nothing. The slow
release pallets seem to take months to dissolve in the motionless
often have a problem getting enough iron and may need more in their
fertilizer. The aquarium fertilizer advertising suggest that
minerals in normal fertilizers are in a form that would oxidize if added to the
water of an aquarium and then not be in a form suitable for the plant to
get. I doubt if this is true as most normal fertilizers are designed to
allow their use with water.
Also from aquarium literature, they often need or
do better with extra Carbon Dioxide. Water hardness should be greater than
50 ppm but less than 150 ppm. Salinity should be kept below 440 ppm.
The p.h. should be between 6.0 and 7.5.
If the water is simply topped up when the water
level goes down then the water may build up high concentrations of salts or
other minerals. Apparently, if the plant doesn't want as much salt or
other mineral as is in the water then it can leave it in the water while taking
the water that it was in. I presume that the plant must take the
mineral/salt laden water into its roots then later excrete the unwanted salts
Apparently, the level of salt can be tested by
testing the electrical resistance of the water. Unfortunately the level of
resistance also changes with the addition of fertilizer. More on this is
in the following link:
For those that have difficulty with keeping plants
emersed in water where other people have no problem, I would look closely at
water quality. Water quality issues for plants in soil pots is dealt with
well at the following link
I would expect most of the issues in this to apply
only probably more so.
I have seen lists of plants that are meant to not
like having high levels of fluoride. I notice that many of the plants in
these lists are plants that are known to be able to be a hydrophyte.
Obviously, these plants need a particularly low level of fluoride in the water
when grown emersed.
Putting fertilizer in the water has a further
disadvantage in that it increases Algae. This alone makes it well worth
trying to grow the plants without fertilizer.
E) Algae is one of the major problems with
growing plants in this manner. I think that that the major reason so many
people who do it keep changing the water at regular intervals is the fact that
the algae is unsightly, not that the water needs to be changed. In fact I
have seen the theory expressed that the algae on the plant roots is actually
advantageous for the plant in its oxygen exchange. I would like to get
more information on this.
Possible things that can be done to reduce algae
are as follows:
1) Try to deny the water any light. With
glass vases try to shade the vase from as much light as possible. In a
modern house/display you can use food dyes to color the water.2)
Snails may be useful. I have yet to try this.3) There are algae
eating aquarium fish but I believe that you would need a very big aquarium and a
lot of plants before you could support one small fish in a self-sustaining
environment. (I would love to get figures on just how large it would need
F) Choice of plant is one of the most
critical things. Aspects that I use are as follows:
(i) Plants mentioned in books or on the internet
that someone has done this with. This will often only mention a family or
genera not an exact species so if the first attempt doesn't work it doesn't hurt
to try a different species of the family.. Typical lists on the internet
are as follows:
Note: I use to have quite a few bookmarks on this
but I seem to have lost them. If anyone can give me some others please do
(ii) Plants that are known to root in
(iii) Plants that are known to like or put up with
a wet soil environment are more likely to survive emersed. Regardless of
that many desert plants also work.
(iv) Known aquatic plants. Most plants used
fully immersed in aquariums are actually grown by the aquarium suppliers as root
emersed plants. Of all the aquarium plants the only ones that seem to be
known as good in low light conditions are the Anubias and Cryptocoryne (both of
which are aroids) plus a number of aquatic ferns.
(v) Most climbing plants seem to have this
(vi) The cheaper the plant and more common the
plant is, (ie commonly sold in Woolworths, K-mart, supermarket etc) the
more likely it is that it has this sort of feature. That is, easily grown
plants that are often resilient to the masses are more likely candidates.
(vii) A very high proportion of the plants
mentioned are in the Aroid family (Family Aracea). Almost all the main
terrestrial genera of the aroid family seem to be there. In
Philodendrons. Some references are more
specific and say the vining Philodendrons species within this Genus. I'm
not sure about the self heading Philodendron species other than
Monstera. (Split leaf Philodendron)
Even if it hadn't been mentioned I would have expected it based on its ease to
root in water.
Spathiphyllum (Peace Lilies). There is a
tradition of keeping these with roots in emersed in gold fish bowls. There
is a controversy on this in that the fish (typically a male Beta fish) are
sometimes sold as if the fish could survive without being fed. In nature
the Beta lives on a diet that consists predominantly of insects and insect
larvae. When starved of this they appear to hold off starvation by
nibbling on the roots. They often can end up surviving several months,
just long enough for people to think that the problem is something in the
water. As far as I know the controversy is purely with the fish. The
Peace Lily in water works fine and is often used as an emersed plant coming out
of an aquarium. There are a number of species in this family. Some
probably a lot better than others. It would good if we could get of
listing of the most likely and least likely species within these larger genera.
Zantedeschia (Calla Lilies)
Aglaonema (Chinese Evergreen)
Dieffenbachia (Dumb Cane). I haven't tried
this but it is interesting that it keeps being mentioned as it is also a plant
that is always described as being very easy to get root rot.
Scindapsus Aureus (Pothos, Devils Ivy)
Pothos and Philodendrons may even have some use as
Aquarium plants: See
I'd take this last comment with some caution as I
have seen references to other people who have tried and failed. Many of
the terrestrial plants that are known be hydrophytes get themselves on the false
aquatic plants lists. These are cheaper plants that some aquariums try to
pass off as aquatic plants and when fully immersed last just long enough to fool
some people that it's their fault that they died. See http://www.thekrib.com/Plants/Plants/bog-plants.htmland
Anthuriums aren't normally listed but the
following link shows a picture of an Anthurium growing in water culture with an
inert medium. (along with a number of other water culture plants)
Some plants that will grow in water are quite
surprising. Although orchids aren't listed very often as suitable plants
the following link give full information on their culture this way:
The absolute best plant I have found for
growing in water is a non aroid called: Dracaena Sanderiana (particularly
D.S. Virescens). Its many common names include Lucky Bamboo (its not a
bamboo but looks a little like a bamboo or corn plant) and Chinese water
bamboo. Its use growing emersed in water has a long Oriental history which
I understand features in both Buddhism and Feng Shui.
Clean all dirt off the roots. Trim the roots
and place in water. Apparently in Buddhism you are not meant to feed it or
change the water. Just replenish the water when it gets low. With a
reasonable sized jar it takes a couple of months before you even have to top the
Instructions similar to the above were apparently
given by Quan Yin (The Goddess of Mercy) when giving this plant to
Buddha. Actually, I don't know whether it was Quan Yin
that gave it to Buddha or the other way around. Maybe some kind reader of
this will correct me or give me a reference on this.
This plant kept in water is also meant to be
particularly good by Feng Shui. By Feng Shui the best place to place to
keep it is just inside a doorway. It will give increased
prosperity/happiness etc if the jar contains either 3 or 4 plants (i.e.
depending on the Feng Shui Text)
Like almost all plants in this category it looks
best with the roots on display in a glass Vase. This also makes it
obvious when the water gets low. At home with a reasonable amount of light
on the Vase the water gets just a little dirty after a few months. That's
enough for my wife to run off and change the water. At my office with the
same plant the water remains clear enough for my likes and I haven't changed it
in over a year. Actually, its been surprising how clear the water is as
other plants in the same area have their water going green. I have
wondered whether this plant had something in it to suppress algae.
A related plant Dracaena fragans (Common
names: Corn Plant or Prosperity plant) also works well but in this case you are
recommended to fill the bottom of the glass jar with pebbles. It's
amazing how quick this plant's roots burrow into the pebbles.
I hope some people
can help me with my questions and I welcome all to correct my