A copy/paste job from a previous post:

Sphagnum peat and coir have nearly identical water retention curves. They both retain about 90-95% of their volume in water at saturation and release it over approximately the same curve until they both lock water up so tightly it's unavailable for plant uptake at about 30-33% saturation. Coir actually has less loft than sphagnum peat, and therefore, less aeration. Because of this propensity, coir should be used in mixes at lower %s than peat. Because of the tendency to compact, in the greenhouse industry, coir is primarily used in containers in sub-irrigation (bottom-watering) situations. Many sources produce coir that is high in soluble salts, so this can also be an issue.

Using coir as the primary component of container media virtually eliminates lime or dolomitic lime as a possible Ca source because of coir's high pH (6+). Gypsum should be used as a Ca source, which eliminates coir's low S content. All coir products are very high in K, very low in Ca, and have a potentially high Mn content, which can interfere with the uptake of Fe.

I have done some testing of coir and CHCs (coconut husk chips) with some loose controls in place. After very thoroughly leaching and rinsing, I made a 5:1:1 soil of pine bark:peat:perlite (which I know to be very productive) and a 5:1:1 mix of CHCs:peat:perlite. I planted 6 cuttings of snapdragon and 6 cuttings of Coleus (each from the same plant to help reduce genetic influences) in containers (same size/shape) of the different soils. I added dolomitic lime to the bark soil and gypsum to the CHC soil. After the cuttings struck, I eliminated all but the three strongest in each of the 4 containers. I watered each container with a weak solution of MG 12-4-8 with STEM added at each watering, and watered on an 'as needed basis', not on a schedule. The only difference in the fertilizer regimen was the fact that I included a small amount of MgSO4 (Epsom salts) to provide MG (the dolomitic lime in the bark soil contained the MG, while the gypsum (CaSO4) in the CHC soil did not. This difference was necessary because or the high pH of CHCs and coir.) for the CHC soil.

The results were startling. In both cases, the cuttings grown in the CHC's exhibited only about 1/2 the biomass at summers end as the plants in the bark mix.

I just find it very difficult for a solid case to be made (besides "It works for me") for the use of coir or CHC's. They're more expensive and more difficult to use effectively. The fact that some believe peat is in short supply or unrenewable (no where near true, btw) is easily offset by the effect of the carbon footprint of coir in its trek to the US from Sri Lanka or other exotic locales.

That's the view from here. YMMV

Al

Oddly enough I was about to ask you about CHCs. I saw a BAAG at The Grow Show in Ann Arbor (hydroponic specialty store). I had never heard of CHCs before. The Grow Show was the first place in the area that I'd seen that was selling the stuff. There's something about that place that makes me wonder if going there will put me on a list of suspected marijuana growers. You get that feel when you go into that place.

Is peat a real must have? It's actually kinda expensive here... and sorta hard to find...

It depends on the experience you want with your plants..:-)

Mike..:-)

I'm not quite sure what that's supposed to mean... O_o?