Growing media can be a mixed bag, so it's important to keep an
eye on your options. You never know when something new might burst on the scene
or when something about your current growing media will change. For example,
according to the Canadian Sphagnum Peat Moss Association, some Canadian peat
companies will be raising their prices 7-15 percent this year, due to the
declining value of the dollar and the ubiquitous rain season. While this
certainly does not affect all growers, it does highlight the importance of
knowing about alternative growing media.
One component that may be worth experimenting with is coir.
Manufactured from the fibrous husks of coconuts in exotic places such as Sri
Lanka and India, coir has emerged as a relatively new growing medium. But the
question is, how well does it work? Growers from all over the United States
shared with GPN the advantages and disadvantages they've experienced in using
When you see coconuts at your local grocery store, you are
actually seeing them naked. Immediately after they are plucked from trees, the
coconuts' extremely fibrous husks are stripped and jettisoned into piles of
composting waste. After being soaked in water for at least six weeks, the tough
fiber, known as coir, is extracted mechanically and spun into yarn. These thin
fibers are immensely tough and can be coiled, stretched and compressed without
losing any of their strength. For many years, coir was primarily used for
ropes, mats and other forms of carpeting.
But the environmental benefits of coir have been gradually
illuminated, creating a larger market. Composed of strong cellulose fiber with
high lignin -- which hardens and strengthens cell walls -- content, coir
displays a strong proficiency for holding air and water. The golden,
100-percent organic fiber has been found to be an excellent deterrent against
erosion and could facilitate vegetation in slopes by being spread out in vast
Coir's benefits were quickly realized in growing media as
well. Initially beginning in the Far East, the trend of using coir in media
quickly made its way through The Netherlands and Canada before finally becoming
a staple of hydroponic rose growers in the United States. Ron Ferguson, a
horticultural consultant and representative for Millenniumsoils Coir, St.
Catharines, ON, Canada, estimates coir has been used by U.S. growers for six or
seven years and is being used more all the time. Today, coir is used not just
for hydroponics, but for annuals, perennials, vegetables and more.
There are several advantages to using coir. First and
foremost is its excellent wetability and overall consistency. Whether it is 6
percent or 100 percent of a mix, growers seem to experience the same
satisfactory results. John Roue, of Frey Brothers, Inc., Quarryville, Pa., uses
6-15 percent coir in his soil mixes and says, "It acts as a natural
wetting agent within the mix. It also gives improved physical properties. . .
reduces shrinkage and compaction of the mix and. . . allows [for] better air
A tangible result of this improved aeration is the
encouragement of larger, healthier roots. "It initiates roots faster than
anything I've ever seen," says Ferguson. "[With bag roses], in 20
percent coir compared to none, plants in coir had roots starting [to grow]. . .
with 50 percent coir, we had roots going into and throughout the bag. And with
100 percent coir, there was a complete root ball in the same period of
time!" Virtually all growers using coir experience improved root growth.
"I don't know if I can exclusively attribute it to coir, but we have phenomenal
results propagating now, with very few losses," says Ted Biernacki of
Ted's Greenhouse, Tinley Park, Ill. "The rooting is just
The cost and handling of coir has also shown improvement.
While it has been more expensive in the past, the price is no longer a problem.
Cost is often dependent on how the product is shipped: Stringy, rope-like coir
is more expensive because it is ready for use immediately, while coir
compressed into the form of bricks or a pallet is cheaper because it needs to
be expanded before use. "I get it by the seat container, so it's a lot
cheaper," says Andy Pierce, Montgomery Roses, Hadley, Mass. "It's
compressed more than peat moss. If you buy a brick-sized [portion], it's
compressed like 9:1. . . so when you add water, it expands."
The resiliency of coir is also very impressive but differs
depending on age and form. "I've seen coconut with four years or more on
it. . . and watering each day with liquid fertilizer," says Ferguson,
"that hasn't dropped an inch in the bucket. . . There's a secret to that,
though, in that it's pre-composted." Newer coconut husks, however, haven't
had the opportunity to linger for years, so its lifespan is shorter -- usually
up to two years. Coir that has a lower amount of fiber, containing more pulp,
also has a shorter lifespan. "It all depends on the condition of the
material and the type of coconut you're using," says Bill Young of Aspen
Nurseries Watsonville, Calif. "The finer it is, the faster it decomposes;
the coarser it is, the longer it lasts."
Another important advantage of coir is that it is
environmentally sound. True or not, many argue that sphagnum peat moss is a
depleting resource and have obtained strict regulations on it in order to
protect the bogs it is extracted from. Coir, on the other hand, is essentially
a waste product, accumulating in biodegradable heaps in Sri Lanka and India.
For many growers, using a surplus product is an additional plus -- yet many of
them view coir as more of an amendment to peat than a replacement for it.
"It's like a synergy effect," says Roue.
"Coir actually improves peat by allowing the water to be taken in more
readily, without the aid of a wetting agent." Roue goes on to say that
peat improves coir by providing a particle size that is very suitable to container
production. Doug Cole, of DS Cole Growers, Loudon, N.H., uses a similar mixture
called CocoPor from Stender, and he also attests to the synergy. "Now [our
media] mixes more consistently," says Cole. "So when we get our bags,
open them up and mix [the media], we don't find furballs of coir."
The most common problem involving coir is that growers order
a batch and discover its EC is through the roof. They then decide to leech it
in order to alleviate its high salt content. What they might not realize,
though, is that the coir is salty because the supplier washed the coconut husks
with salt water instead of freshwater. This problem could easily be resolved.
"Make sure you're buying from a reputable dealer," Ferguson warns. "There
could be some cheap stuff out there that is no good." Cheaper coir
requires the additional labor of leeching, while more expensive coir is already
at an acceptable EC level. Ultimately, it is up the grower to decide which is
Another disadvantage of coir is its clumpy form, which may
not move smoothly through all pieces of automated equipment. Though there are
other, more pulpous forms that may be better, growers might still object to
some of the changes that coir necessitates. "Coir has a lot less cation
exchange capacity, [and] you'd have to change your fertilizing practices,"
says Martin Stockton, First Step Greenhouses, Temecula, Calif. "It's
[also] a lighter brown color, and as a grower, you tend to use color as an
indicator of how moist the soil is. . . basically, you'd have to reeducate your
Reeducating your growing staff is a decision based on
personal preference of the grower. Similarly, there are some indirect effects
of coir, such as minimizing labor cost and preventing the spread of algae and
fungus gnats, that fluctuate greatly depending on personal growing habits and
environment. Growers that do not experience these results may find themselves
at a disadvantage; however, it is only because so much is contingent on circumstance.
Minimizing labor cost is a possible result because coir has
a high wetability and, therefore, could be watered less, saving labor. Yet many
growers actually water more, albeit in smaller amounts. Roue offers an
explanation: "If you had the capability to measure the actual volume of
water, then the volume is probably less. The frequency should be a longer
interval between waterings, but then again, there are different types of
growers." The indirect advantage of saving labor is directly related to
the personal watering habits of the grower.
The possible prevention against the spread of pests is also
related to habit. "There have been reports saying, 'Oh, well, fungus gnats
will still go in there.' Yes, they will," says Ferguson. "But I have
not seen an outbreak occur as fast with coir." Cole agrees, "I would
never say, with 7 percent coir, we're in some way deterring fungus gnats. . .
[but] I would say it helps dry out the top surface, meaning it's not as
desirable to a fungus gnat to come lay its eggs." Since the spread of
fungus gnats is directly related to the wetness of topsoil, then how well they
are controlled depends on the grower's watering preferences. Similarly, algae
also thrives when the topsoil is wet and, therefore, may also be prevented in
some degree based on watering frequency. However, for both algae and fungus
gnats, one of the most important factors is the environment, which can be
unpredictable and differ greatly from location to location.
Coir certainly has its advantages -- increased wetability,
improved root growth, good resilience, environmental friendliness -- but the
trend is to mix coir with other components such as peat in order to reap the
benefits of all the elements in the media instead of just one. As for coir's
disadvantages, some are preventable; talking to your supplier can easily deter
imported amounts of coir that are too salty, chunky or fresh. Other
disadvantages largely depend on how comfortable the individual grower is;
minimizing labor cost and the spread of algae depends largely on personal
growing habits, and spending time reeducating your growing staff may not always
be a workable option.
However, if you decide to try coir, it's important to
understand the pros, cons, conceptions and misconceptions. After all, it is
only by doing so that you can really decide whether or not coir is right for
In a constantly changing world, it's hard for anything to remain static -- even growing media. For many growers, coir has been an attractive component. But how well does it really work?