Pat: Light means just that; relatively light weight soil mix
with lots of
air space as described. Soil mixes must drain easily for
bonsai to thrive.
A heavy compacted soil would hold moisture too long and cause
root rot and
other ills.
Alan Walker

Generally, though, "heavy" soils will be higher in organic
material that holds water (making the soil even heavier!) and
will have a finer texture -- especially after being in a pot for
a while.

Pat's soil probably could/should be "heavier" than mine since
he's in the dry desert and doesn't want to water 4 times a day.
So his should be designed to hold on to the wetness a bit longer.
With relative humidity in the single digits or teens and
temperatures up in the 90s or more he probably has a time keeping
his trees wet enough.

I have temps in the 90s, too. But my relative humidity is
usually a minimum of 50-60 percent (or more) in the summer.
Water evaporates from soil a lot more slowly (and we Southerners
MOVE a lot more slowly ;-) with that humidity.

Jim Lewis - - Tallahassee, FL - Where the
humidity has been hovering around 20 percent lately and where our
rainfall is already down 7 inches for 2004.

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