Botanists at the Royal Botanic Gardens in Kew this week threw their
support behind a replacement for peat which was launched last month by ICI.
The material, called coir, is derived from coconut husks and has been under
trial at Kew for more than 18 months.
Kew, which houses a collection of around 25 000 species of plant, is
committed to phasing out the use of sphagnum moss peat because of concerns
about the long-term future of peatlands as unique habitats, which are rich
in fauna and flora. Mike Sinnott, the assistant curator of the herbaceous
section at Kew and the coordinator of its search for alternatives said that
Kew is keen to endorse coir in the hope that amateur gardeners and commercial
horticulturists will switch to it from peat. 鈥榃e see it as being a good
alternative that takes the pressure off the bogs,鈥� said Sinnott.
Kew no longer uses sphagnum moss peat for cultivation on open ground.
And 95 per cent of Kew鈥檚 compost mixes for potting now contain coir instead
of peat. 鈥榃e were able to take peat out and put coir in with virtually no
alteration in volume, nutrient mix or acidity,鈥� said Sinnott.
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鈥楾he most difficult thing was coming to grips with watering and feeding
requirements,鈥� he continued. 鈥榃e found there was a need for more nitrogen
fertiliser than with peat-based composts. Coir holds water very well, but
people misjudge the amount of water it鈥檚 holding, so people who switch to
it have to develop a feel for it.鈥�
Despite the apparent success of the product at Kew, Sinnott was at pains
to point out that the situation is different in commercial horticulture.
鈥極ur plants are individually cared for, and we monitor and watch closely
for deficiencies,鈥� he said. 鈥楤ut in mass production, it鈥檚 more difficult
to get the regime right.鈥� He added that if there鈥檚 going to be a significant
shift away from the use of peat, 鈥榠t鈥檚 really the commercial growers who
need to put the effort in鈥�.
John Clowes of ICI Garden Products explained that ICI derives coir from
coconuts grown in Sri Lanka for food and fuel. Once long fibres have been
removed from the husk for use in rope, matting and cloth, coir fibre pith
is all that is left. 鈥楿p to now, there has been no use for coir, a brown
powder, and coconut-farmers have been putting it into huge piles of 10 000
tonnes or more. These 鈥榤ountains鈥� have been building up over many years,鈥�
said Clowes.
He said that Sri Lanka has a good stock of consistent quality. After
blending coir from a number of sources, the company reduces the acidity
of the material and adds to it a proprietary blend of nitrogen, phosphorus
and potassium fertilisers.
鈥業t鈥檚 a multipurpose compost suitable for seeds to germinate in and
cuttings to root. It suits all plants except acid-loving varieties such
as azaleas, heathers and rhododendrons,鈥� said Clowes. Although coir is
about 20 per cent more expensive than peat, he is confident that people
will be prepared to switch to it in order to save peat bogs.
