tapla said... "Ideal pH for container gardening is about 1 whole number lower than growing in mineral soils" Again, you've simply thrown out another statement un-tethered to anything... I know, I know you intended it to be that way... but why? I've no idea. As far as water holding capacity... you choose to present it based upon weight where dried peat is going to be much lighter than an equal volume of coir and so appear to hold more water but to my thinking basing water holding capacity on volume would likely be more relevant for the gardener (in either container or in soil). This I've done myself and am quite sure coir is going to expand far more with a given volume of water. Water holding capacity is important provided air pore spaces remain equivalent... however perlite, pumice, or vermiculite is so often suggested as an addition with peat potting mixes to make one wonder why the need for these components... likely to maintain the air pore spaces due to compacting as the peat degrades and thus collapses within one growing season, its lignin content notwithstanding (btw, coir has significant lignin content as well, especially considering percentage of weight). And as every gardener knows, maintaining the air pore space is critical for healthy root development and growth of a good many plants (but not all plants however). Holding luff then is the important feature and not necessarily lignin content. Again, a simple comparison study would prove out which material best maintains adequate air pore space over time... so could you point me to one or more of these studies? I don't know the answer but would definitely like to see some studies conducted that could enlighten me on this subject. Until then, I've got to say the jury is still out... there's lots of theory out there but empirical evidence is what's called for to solve this particular inquiry. tapla said "Allelopathy - High levels of phenolic compounds known to be present in coir ... can profoundly affect root morphology, limiting length, number, and size of all orders of roots" From the foregoing statement I gather you're saying that coir has an allelopathic effect on ALL rooted plants? and thus you cannot and/or need not supply a list of affected plants... is this a correct reading of what you're meaning to infer? I'm surprised that this allelopathy of coir is not mentioned on the Internet somewhere... or at least from the simple yahoo search I've done so far. I'm so intrigued by this new piece of information that I'm going to take it from a theory and try to come up with empirical evidence of it by planting some radishes in dixie cups... a half dozen in a 50/50 with peat/soil and another half dozen in 50/50 with coir/soil... the soil will be the same (coming from my garden to supply the micros and biology) and then water the same amount each day with one teaspoon of Jack's Classic into a gallon of water. In approximately two weeks I'll wash the soil mix off the roots and compare. Do you see any complicating factors I should be aware of before beginning this little experiment? I'm excited. (BTW, the reason for radishes is merely speed of germination and the roots will not swell if I end the experiment too soon... I don't have the time or patience to carry on anything that's going to take more than 2 weeks at the most to complete... also I already have everything I need to do this in the shed right now). EDIT: In my search for allelopathic connection between phenolic compounds and plant root growth I came upon these tidbits from two separate sources... make of them what you will but they sure seem to complicate matters with previous claims of allelopathy of coir over peat... "Once the coir is freed from the fiber it goes through a maturation process to stabilize the product and this can take up to 6 months. During this process salt, tannins, and phenolic compounds are removed. It is buffered, washed and calcium nitrate is added to displace sodium and balance the pH." "Sphagnum and the peat formed from it do not decay readily because of the phenolic compounds embedded in the moss's cell walls." So does that mean peat too is allelopathic to plant roots? If so, then its a wash and I'd be wasting my time conducting the simple radish experiment? Final UPDATE: Okay I give up... After a single search I've already found several references to peat and peat bogs as being allelopathy to the germination of certain plants... I'm going to call the allelopathy claims against coir and peat a wash.

I am located in the Melbourne area. (beachside/Indialantic) Wow... that's quite a read. I'm probably not too inclined to do a lot of soil mixing, especially where composting is concerned. (I just don't have the space to mix OR store) This would be one of the main reasons that I lean more towards a hydro/organic approach, using soilless media. Watering is no problem. I have time to water, or I am quite adept at automating. The local hydro store can get me coco cubes and all the coco specific nutrients. I have (low/no cost)access to cloth pots from a local nursery. The climate here is my big limitation. I am not opposed to trying anything, so long as it's within my means, objectives, and criteria. I have a very large screened in area that has a west facing shaded overhang that the screen cage attaches to. It can be utilized to provide a good mix of sun/shade by simply sliding the containers forward or backward into/out of the sunny zone. Or I can expose the containers to full sun, minus the 15-20% loss from the screen. Anyway, I've been looking at all sorts of pots, from cloth to "airpots". (which I certainly can't find locally) I like the idea of containers that encourage "air pruning" of roots, rather than containers which become root bound and run roots in a circle around the pot. But if something works better, I'm all ears. I'm going to be raising indeterminate tomatoes, as I have hydroponically. I assume that i can use the same pruning and staking methods? Specifically, I trim back to one main stem, and pull of all suckers. Basically, I just have one long vine, with just 3-4 sets of leaves (side shoots) on the end. Anyway, thanks for your reply. Can't wait to jump deep into this topic.

I use coconut coir to start all my seedlings. It is wonderful because there is no organic material in it therefore no food to attract gnats who's larvae feed on the roots of young daylilies planted in potting soil. I have even left out a couple of containers of daylilies planted in coir over winter (not intentionally but they got forgotten in all the rest of the work I had to do ) and discovered that the daylilies do return . I also have used it to amend gardens in my yard that are very heavily laden with clay to lighten up this soil. I highly recommend it . It also helps to hold moisture ( like peat) but is a renewable resource unlike peat.

I think the drying times that you calculated with the pumice will be detrimental only if you water the plant/pumice while it is still wet. Beyond that, I think you may be over-thinking this and over-worrying. I get 1/8" pumice from General Pumice Products here in the U.S. I just sifted and washed a bucketful over the weekend. It is drying in big oil pans outside -- and right now, it's really cold here in SW Florida. I don't think it will be fully dry until Thursday, and that will be 5 days. Chris is right -- use unglazed terra cotta pots if you can. Even with pumice, they will remain lightweight. Haworthias in pumice shouldn't need to be watered more than once a week, unless you live in hot southern Florida in the summer. Even then, mine only get watered about every 5 days. You don't HAVE TO water a Haw the very minute its mix is dry. You can wait a day or so and it will be fine.