Dear IBCers:
This is another one of those things that we will be debating for many
years.... I tend to agree with Brent. I hand-water, from above, three
times with at least a 15-minute interval. Accumulated salts, are
usually washed out by the second and especially the third watering.
Of course, this is my Humble Opinion!

Carl L. Rosner - near Atlantic City zone 6/7
http://bmee.net/rosner
http://www.jamesbaird.com/cgi-bin/Ja...d=00000068 48
http://www.jamesbaird.com/cgi-bin/Ja...d=00000068 48




Brent Walston wrote:

Folks

It's not a REALLY big deal, unless you live in a hard water area, BUT
there
most certainly is a difference:

When you soak a plant (dunk it), it sits in the same volume of water
without any active circulation. The soil gets saturated. When you lift it
out, it drains. There has been a flush with only the volume of drain
water,
regardless of the size of the container used for soaking. If you don't
let
water go above the rim of the pot, but rather let it get to the top by
capillary action, there is effectiviely NO flushing action of the top
layers of soil. Each watering will add a little more salt deposit as the
water is evaporated or absorbed by the plant

When you water from above, the reverse is true. The top layers of soil
are
continually bathed in fresh water with a less than saturated amount of
dissolved salt. This tends to dissolve any salt left behind by the
evaporation of the previous watering. Additionally, as the soil becomes
saturated, it drains, and additional watering will flush the soil with
many
times the volume of the pot depending on how long you water. If you
are in
a hard water area, watering overhead by a mist irrigation spray or
other system
attached to a timer allows you to flush virtually all of the dissolved
salt
that is practically possible.

The same is true of air flow through the soil mixture, although I doubt
this is as important as the salt flushing action of water flow. If you
dunk
your plant, the water drains out the bottom and pulls in a fresh
charge of
air behind it. One change of air, but probably adequate. If you water
from
above much more air will be pulled through the soil mixture, unless you
water with a firehose and have some way of not blasting out the soil.
Hey,
glued on rocks!


Brent in Northern California
Evergreen Gardenworks USDA Zone 8


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