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GROWER
by Dr. Lynette Morgan
Q
What would be the best way to plant a sprouting seed in aquaponics?
Mesh pot with stonewool or just clay pebbles surrounding the seedling?
Thanks, Toefur
a T
he best way to sow a seed into an aquaponic system
would depend largely on the type of seed you want to
germinate. Smaller seeds such as tomatoes, capsicum,
and many other vegetables would be best supported in the
mesh post with stonewool or a similar moisture retentive
medium, which will ensure there is enough water and
oxygen around the seed and young plant for early devel-
opment. These types of growing mediums also provide
the support required for smaller seeds as they can easily
become dislodged when substrates with a larger particle
size are used, particularly if this is an ebb and flow type of
aquaponic system. Larger seeds (especially those that are
pre soaked before sowing) can be started in smaller grade
clay pebbles, however, since clay pebbles don’t retain
a lot of moisture and are very free draining, particular
attention needs to be paid to the frequency of irrigation in
the aquaponic system to ensure the seed or young plant
never dries out during the critical establishment stage.
Clay pebbles do have the advantage of being very highly
aerated, so oxygen should not be limiting to the seed or
seedling, however, moisture levels can be restrictive in
the upper levels of the root zone where seeds are usually
placed for germination. In these types of systems, salt can
also accumulate on the surface of clay pebbles, which may
restrict germination of some species. As a compromise, it
is possible to use one of the small propagation cubes of
stonewool (one inch across) to hold the seed and place this
cube directly down into the surface of the clay pebbles —
the young plant will rapidly grow roots through the cube
into the clay pebbles without the requirement for a mesh
pot and a large amount of stonewool.
Kind Regards,
Dr. Lynette Morgan
LM Dr. Lynette Morgan holds a B. Hort. Tech. degree and a PhD in hydroponic greenhouse production from Massey University,
New Zealand. A partner with SUNTEC International Hydroponic Consultants, Lynette is involved in remote and on-site
consultancy services for new and existing commercial greenhouse growers worldwide as well as research trials and
product development for manufacturers of hydroponic products. Lynette authors five hydroponic technical books.
Visit suntec.co.nz for more information.
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Maximum Yield