The following is a companion video for an
article that I wrote for our friends over
at Bright Agrotech.
A link to the article can be found in the
description field.
As with most businesses, we tend to try to
reduce waste as much as possible, this ranges
from cutting costs in materials to reducing
the amount of labor to complete tasks.
As part of our own cost cutting goals, we
developed the GrowGrip for growing leafy greens.
They eliminate the need for using disposable
rock wool cubes or mixing potting soil, as
well as removing the hassle of using bulky
net pots.
As a companion to using the GrowGrip, we recommend
that our clients start their plant seedlings
(typically lettuce) in a simple wicking tray.
This allows for hundreds of plants to be started
in a small wicking tray.
Once the seedlings are a couple of weeks old,
the best plants can be sorted and put into
the GrowGrip.
We have also found that this seedling starting
method also works well with the Bright Agrotech’s
ZipGrow Towers, as you don’t have rock wool
cubes or potting soil leach through the towers.
We start by using a pH neutral gravel.
We use expanded shale since it is half the
weight of regular gravel, however most gravels
will work well.
To obtain the proper consistency, it is run
through a 3/8” screen made from standard
hardware cloth, then the smaller fines are
removed by screening through a regular window
screen.
A standard 1020 tray works well and will hold
roughly 500-600 lettuce seedlings in a single
tray.
The tray should hold about 1.5” of gravel.
To keep the gravel consistently moist, we
like to take a plastic bottle and drill a
hole through the side of the lid.
Then fill the bottle with nutrient water and
place it in the wicking tray so that the bottom
of the tray maintains a thin layer of water.
The gravel will wick up the water and keep
the upper layer damp enough to germinate the
seeds.
Depending on the gravel type, it may take
some experimenting with the thickness of the
gravel, or depth of water.
To plant lettuce seeds, we simply sprinkle
the seeds over the gravel then gently smooth
out the surface to slightly cover them.
After a couple of days, you should see sprouts
and they tray can be placed in direct sunlight.
It’s important to make sure there is always
water in the bottle as the plants can quickly
dry out when the reserve is empty.
For maximum germination, it is best to use
a temperature controlled heating mat in cooler
climates or to keep the tray out of direct
sunlight in warmer climates until the plants
have germinated.
After about two weeks, the secondary leaves
should be mature and the lettuce will have
a strong enough root system to transplant.
We just gently grab a clump of the greens
with one hand, then run our fingers through
the gravel to loosen it up and the group of
lettuce will come right out.
A slight shake and the majority of the gravel
will fall off the roots with little damage.
Since the roots are not too long, the plants
can be separated and individually placed into
the GrowGrip.
We have also found that this is an excellent
technique for transplanting seedlings into
a ZipGrow Tower, or even transplanting into
media beds or soil gardens.
Using this simple wicking tray helps to save
growing space by having tight clusters of
plants, saves money and the environment by
using reusable gravel, and helps to maintain
a clean system by not having rock wool or
soil mixtures get into your hydroponic or
aquaponic system.