Coconut coir, a by-product of the coconut industry, has been promoted as an alternative
to peat moss in soil-less media. Sphagnum peat moss has long been a standard
component of soil-less media, but some people have expressed concern that it is a non-
renewable resource. Although it does not appear that world peat resources will be in
short supply for a very long time (see www.peatmoss.com), coconut coir may have
characteristics that make it a useful component of soil-less media mixes. Coir has
been considered to promote excellent plant growth but there are few rigorous studies
that have compared it with peat moss control plants. However, ten years ago, Meerow
(1994) found that growth of Ixora coccine was significantly reduced compared to growth
in a sphagnum peat moss control. Vavrina (1996) found that there were no adverse
effects of coir to tomato and pepper transplants, but a subsequent study in the same lab
(Arenas et al., 2002) found that media with more than 50% coir had reduced growth
compared to peat-grown control plants. They suggested that a high N immobilization by
microorganisms and a high C:N ratio in the coir may have caused the reduced growth.
Lopez-Galarza (2002) found that root development of strawberry plants grown in peat
moss was better than in coir in some, but not all, studies.