WATERING
Those with outdoor bonsai generally have a number and water with a garden hose. They
should direct the water into the tops of the trees to dislodge dry leaves, discourage
insects, and allow water to fall like rain to not disturb the soil in the pot. If
the level of the soil is 1/2" below the rim of the pot, a 1/2" of water will
collect. This water may take 5 minutes to be absorbed and may wet an inch of soil.
When the plant is watered a second time, it will be absorbed a little faster and may
wet another inch of soil. But if a pot is 6" deep, it may take six watering
passes to wet the entire soil mass. Bonsai books tell you to water as many times as
necessary until you see water coming out of the drain holes of the pot.
But even that is not adequate if the potting media is compacted and has shrunk away from
the pot. In this situation, water will travel down along the sides of the pot and
out the holes without penetrating the root mass. Too often when we accept new
memorial bonsai for the Hawaii State Bonsai Repository, we find that there are absolutely
no roots in the center of a dense root mass. After exchanging the media of
alternating pie-shaped sections over several repottings, the trees take on greatly
improved growth.
Generally, watering practices are matched to the type of potting media that you
use. Outdoor pines generally do well in high aggregate-low organic matter media
formulations. Outdoor deciduous type trees need more clay and organic components.
True Indoor Bonsai need a very loose gravelly media so the plant can drain quickly as poor
draining media contributes to root rot caused by over watering. So how much water
and how often?
WHEN YOU WATER, TOTALLY SATURATE ALL MEDIA OR THE ENTIRE ROCK PLANTING! The
ideal method is to soak the bonsai so water can enter from the drain holes in the bottom
of the pot or a rock planting can be sitting in a pan of water for at least 30
minutes. For a potted bonsai, the water should be up to the level of the pot rim and
it will be completely wet when the highest part of the soil is visibly wet. Rock
plantings can be completely submerged under water and its saturated when no more bubbles
come out.
Basically the water has replaced every single air space in the media. When you lift the
pot or rock planting out of the water, some water drains out and you can imagine air
rushing back in. It's this weekly air and water exchange that keeps a True Indoor
Bonsai healthy! Generally, the potted bonsai is watered again when the surface
feels dry. But each plant has a different requirement. Brassaia likes to be
very dry between waterings. Dwarf Schefflera and most others prefer to be watered
while it's still slightly damp. After a while you'll be able to judge when your
plant needs water just by lifting it. A recently watered plant is heavy!
OVER OR UNDER WATERING
If you badly overwater you'll kill the roots, rot the trunks, and kill the plant.
There's not much that can be done if the trunk of the plant is soggy and rotting even if
some leaves are still green. If you forget to water and the trunk is hard with vertical
creases showing, it's dried out, the leaves will have a dull sandpapery appearance.
Trim off the bad leaves, rinse off any rotted areas, totally saturate the media,
and place in a polybag or wide mouth gallon jar. The high humidity will reduce the
load on the roots and roots may recover. After the first new leaf develops,
open the cover for a few days, and if the new leaf stays up, place it back to it's
normal growing area.
HUMIDITY
The moisture in the air is difficult to control. In dry climates, plants will
benefit from being on "Humidity Trays." A simple one would be an aluminum
cookie sheet filled with gravel. Keep water in the gravel but allow the top of the gravel
to be semi-dry in the morning. Place the bonsai on top of this and it will benefit from
the moisture given off by the gravel.
In extremely dry climates, it's possible to create more humidity by using deeper
"Humidity Pans." Some have been constructed with clear acrylic bottoms and
walls as much as 6" high. Gravel or plastic lighting grid panels is placed on
the bottom and water kept below the top of the gravel or plastic panels. Bonsai placed on
this enjoy a greater humidity and the wall help contain the humidity.
This can be carried to a higher level by using an aquarium as the higher walls help hold
more humidity. For use as an emergency first aid station, obtain a piece of glass to
use as a cover or tape plastic sheet to obtain 100% humidity like a terrarium. This
is a good environment for rejuvenating plants that have been dried out, over or under
watered, over fertilized, or those that have been exposed to excessive heat or cold.
PLANTING MEDIA MOISTURE
Soil moisture depends upon the media mix; the ratio of gravel to organic matter and
the size of the aggregate particles. Generally all soil contains aggregate, clay,
and organic matter. Indoor Bonsai mixes should not use clay at all as it will
eventually break down and clog the drainage. Fuku-Bonsai's non-soil media is ideal and
made up primarily of volcanic pumice and peat moss. We supply it as part of workshop
packages and conversion kits. Although the materials are inexpensive it is extremely
costly to ship via Federal Express from Hawaii. We are, therefore, encouraging
the creation of an ideal True Indoor Bonsai potting mix that can be sent more cost
effectively throughout the continental US by UPS Ground. We've made good progress in the
past year and hope to make formal announcements and endorsements in the near future.
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