Page 11 - Griffin Gazette Fall 2016

By Tami Van Gaal, CEA Division Leader FibreDust products will not require conditioning, several hours
should be allowed for the product to fully hydrate prior to use.
Hydroponic production methods dominate
the world of Controlled Environment The newest option for slab production brings an intermediate
Agriculture (CEA). Leafy greens are solution to rockwool and coir. The Easy Plant System from Smithers-
generally produced in obvious hydroponic Oasis utilizes the well-known Oasis phenolic foam in new slab and
systems, including floating rafts and block forms. Like rockwool, the media is inert; it will not interact with
nutrient film technique (NFT) systems. nutrients or crop protection products. Unlike rockwool, Oasis will
Other CEA growers combine container- break down over time. The breakdown process takes longer than
based production systems with an inert or for coir, but mechanical and biological break down will occur over
low reactive media that provides support 18-24 months. This timeline for breakdown means that the product
but little fertility. Examples of this strategy will maintain its integrity during production.
include Dutch buckets and 100% coir media
in traditional pots. However, one production method clearly leads Oasis is a manufactured product. This means that the product
the market for hydroponic production: the slab method. Growers is highly uniform, highly consistent and also sterile at the time of
commonly use the slab method to support hydroponic production manufacturing. The density and pore size are both controlled during
of high-wire crops, including tomato, cucumber and pepper. the manufacturing process. Some of the pores are sized to hold
moisture while others are sized to hold air. Since air is always held in
The slab method ingeniously supports crops from propagation to the foam, the crop cannot be overwatered. Lightweight Oasis foam
harvest while avoiding any stress related to transplant. Propagation brings additional advantages when it comes to shipping costs: Low
begins in a plug. As the young plant matures, the plug is placed weight translates into low freight.
into a dibbled or carved hole in a larger block, generally three to
four inches square. The young plant is grown in the blocks at high The following table summarizes the differences between coir and
density while it quickly roots into the surrounding media. As the Oasis slab systems:
roots penetrate to the edges of the block, the block is placed on
the surface of a larger slab. The roots move into the slab, which will Organic Rockwool Coir Oasis Easy
support the plant for the remainder of its production cycle. No Yes Plant
Mechanical
The slab system has been dominated by rockwool media for many and biological breakdown No
years. Rockwool, also called stone wool, affords several desirable
attributes for production, most remarkable being its inert nature. Inert No Yes Yes
However, rockwool presents a significant drawback: Disposal Sterile
can be challenging because rockwool does not break down. For (at manufacture) Yes No Yes
growers for whom disposal is a problem, two other options now Yes No Yes
exist for slab production. Weight Heavy Heavy Light

Two media alternatives solve the disposal problem while maintaining When moving from rockwool to coir or Oasis, growers should
the integrity of the slab system. Both provide all three components expect to modify their irrigation strategy. Moving to coir may also
for the system (plug, block and slab), and both offer slabs wrapped warrant a slight adjustment to the existing fertility program. Griffin’s
in poly for ease of use, even moisture levels and minimizing algae GGSPro technical services team can provide guidance to making
growth. Therefore, while changing media types will, of course, lead adjustments to maximize crop growth in the new media.
to a change in irrigation strategy, the change will not alter the basic
production strategy. Space utilization and crop stages match the Talk to your Griffin sales rep to place an order for FibreDust grow
known process, right down to the placement of drip tubes. bags, cubes and plugs and the Oasis Easy Plant system. For
Oasis, consider one of their convenient pallet bundles, designed to
The first alternative media to adopt the slab system was coir. Coir has support production of 200 or 300 plants.
grown in popularity as a peat-alternative in conventional production
due to its plentiful, renewable supply and positive attributes for root
growth, including good water holding capacity and high porosity.
Coir offers about half the cation exchange capacity as peat, which
means it hold less nutrition than peat. For all practical purposes,
pure coir presents a hydroponic system.

Coir is considered to be the most environmentally friendly of the
three media types most commonly used in slab grow bags. Of the
three, coir alone provides an organic option; it’s relatively easy to
find an OMRI-listed coir slab. Once the poly bag is removed after
production, the coir can simply be composted. Readily available,
easy to grow in and easy to dispose, cost-effective coir is an
appealing solution for many growers.

Consider a few factors when switching to coir slabs. First, look for a
product with a low EC to avoid the need to leach or condition prior
to planting. Next, look for consistent quality and a blend developed
for your particular crop. Griffin offers the FibreDust product line,
which ships with a very low EC (< 0.5 mS/cm at shipping), readily
available blend options, and strong product consistency. Slabs
ship compressed and dry. They fluff naturally after irrigation. While

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