THE RESERVOIR SYSTEM
When plants are watered from the top
excess water drains out of the container,
and is either captured for re-use or drained
away. However, house plant owners often
put a tray under their plants to capture the
excess water. The container sits in the
water and draws the water as the roots use
the water held by the medium.
To assure that the roots oxygen
requirements are met, especially the roots
which grow into the water, gardeners
sometimes place a fish tank air pump with
aerator attached which constantly moves
the water. Oxygen dissolved in the water is
used by the roots.
This system works best with the drier
mediums, which are impossible to get too
saturated. A mixture of 5 parts lava and 1
part vermiculite is ideal, but mediums which
are compact and hold a lot of water in the
particles are too moist for this system.
Adding a high proportion of lava gravel or
styrofoam pellets helps to dry the medium
out.
With the reservoir method the roots sit
partially in water. The water level can be up
to 20% of the container depth. An 8 inch
high container can sit in 1½ inches of
water, a 12 inch container can have a water
level of 2½ inches. Containers can sit in
individual trays, or for convenience of
watering they can be placed in a single
large tray. Plastic dish trays, lab trays and
plastic kiddie pools all make ideal water
trays, or a watertight tray one can be
constructed from wood coated with plastic