expanded clay pebbles
Cloning Method: If
you plan to start clones
using clay pebbles,
there are two methods
growers routinely use.
There is the low transplant
technique—usually used in
deep water culture—and
the top drip method. The low
transplant technique is simple,
you only need to remember two
things: provide humidity up top, and
plant your node down low in the
pot. In other words, only fill your
net pot about one-third
to one-half full and then
plant the stem 1-in. or so
below the pebbles. This
allows the portion of the
pebbles submerged in the
deep water culture reservoir to act as a wick for the
couple inches above the
water line where the clone
has been positioned. In the top drip method, usually used for drip
systems, starting deep water culture systems or starting ebb and flood
systems, clones are placed directly into their permanent grow site.
Ensure drip emitters are placed close enough to the freshly placed
cutting and there is a sufficient flow rate. With newly planted clones,
whenever possible, I always aim to provide at least three emitters
with a more open flow rate of about 1 gal. an hour. If the pebbles are
properly soaked and the emitters are fastened correctly, clones take
root quickly and easily.
“Its high CEC value means the
clay has the ability to bind with
and hold nutrients for longer.”
Periodically Rinse: It is hard to claim that any hydroponic medium
is 100% inert because most of them have a specific pH value and
cation exchange capacity (CEC). When describing a media as inert,
most growers are really just referring to its lack of ability to provide
any real measureable nutrients, or the ability to take away nutrients
from the plant. With expanded clay pebbles, watch out for the clay’s
high CEC value. Its high CEC value means the clay has the ability to
bind with and hold nutrients for longer. Because of this, you might
eventually notice an encroaching, whitish substance on top of your
pebbles. This white substance is salt residue left over from the solution.
If left to build up for too long, it could eventually lead to phytotoxicity,
which chokes out and starves the plant of water or nutrients. As a
preventative measure, be sure to routinely pull your plants out of the
system (if growing in pots) and rinse from the top down using fresh,
pH-adjusted water. If you’re not using pots, simply leach the entire
system using fresh, pH-ad