This is an excellent brochure--gives definitions of the different components but also talks about pH, drainage, porosity, water retention, etc. etc. Here is a link that might be useful: Container Media (Univ. of Fl.)

I get sick of soggy rocks and bark in the pot deep and the top drying out too quick. peat, rocks,bark, it'll all retain too much water for too long. so don't water the thing till it comes gushing out the bottom and keeps gushing. this big of a pot will hold 8 fluid ounces for awhile, like a week or so putting canadian peat in the thing with bark and rocks works fine for me, peat like that won't absorb water quick, it drains. I can do that though, i check my pot of orchids daily. they jut get a mist a day for a week, then watered lightly, like where water might or might not run out to equal 4 to 6 fluid oz's, so peat, plain canadian peat, works for me. I am just not gonna shell out 12 bucks for a tiny amount of peat. as far as the seedling re flask flask replate or whatever it's called, until they can't quite budge out of a test tube, or whatever, first set of leaves for like 4 months or more afterwards, i think, but not sure. everyone is different about their orchids. i am surprised, mine have lived this long and even co exist amongst other kinds in the same pot. phals seem to do alright, leaving the flowers a little while, but not like 90 days, a month seems fine, then clip those suckers off. i am learning, and,mine might die. so far so good.

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.

Add a small amount of dolomitic lime and do look for coarse perlite. Home Depot has it in the Thermorock brand - if the store doesn't carry it normally they should be able to order you a bag. Make sure it is the COARSE grade and not the medium grade. I think the bag is yellow. No need to unpot your plants right this moment, you can "side dress" with lime and a small amount of bone meal. I'm switching to a peat-pumice blend because I hate perlite and the way it tends to float up and out of the mix. For long term plantings a 70/30 blend (peat to pumice) is probably best. I get my pumice from the feed store where it is sold as Dry Stall - not Stall Dry but DRY STALL. It is crushed pumice. It does need to be rinsed thoroughly, and a compost screen with the correct mesh size makes that a ton easier. I forget the particle size off the top of my head. But if you like what you've got, with the proviso that you switch over to coarse perlite if you're not already using it, there's no real need to change. Keep in mind that the peat will break down over time. It has a maximum life span of about 5 years under ideal conditions but it starts to degrade significantly before that. I'd give it no more than 3 years before you have to replace it. Since perlite is so light you can recondition your mix by putting it in a bucket, filling with water, and scooping the perlite out as it floats to the top, then reuse to make new mix with fresh peat moss. However perlite is pretty fragile and it will gradually break down, mechanically over time. I'm guessing you should get up to 8 to 10 years of use out of it before you have to toss it because the particles have become too small. Screening will help to retain large enough particles and you can discard the dross. Pumice will last virtually forever and won't break down unless you take a hammer to it. However availability is limited. Growstones is basically man-made pumice but it can be quite expensive. However given that it lasts for-virtually-ever, if you amortize the expense over your lifetime, its not that bad. And it comes in larger particle sizes than the Dry Stall, which may be advantageous for some plants (but disadvantageous for others). I hope to be able to test a mix using the smallest available Growstones eventually, but for now I'm working with the natural crushed pumice. It's cheap and the particle size seems to be about right for anything I'd be growing. It's also much lighter weight than Turface, which is a popular substance used by some in some soil mixes. Read and post on the container forum for more detailed information about the pros and cons of various mixes for specific plants. I think your jasmine will do fine in the blend you have, but I'm not familiar with the other plants. There is a strong bias there for one particular blend - well, two. What is called 5-1-1, which is a pine fines based potting mix very similar to most commercial potting soils (but with some advantages) and what is called "gritty mix", which is Turface based, coarse, and well-draining, intended for things like potted trees, cactus and other succulents, etc. I don't think there's anything particularly wrong with either mix, except that pine fines are difficult to find for many people, and becoming ever harder to find as time passes; and Turface can also be hard to find and it is VERY heavy. If you can find pine fines affordably where you live (its basically small pine bark mulch or may be sold as soil conditioner) then a 5-1-1 mix would probably suit all or most of your plants except the African violet, which is undoubtedly fine where it is. Again, other than the jasmine, I'm not familiar with the rest of those plants, so asking someone else on the container forum would probably get you better information, with the understanding that there is very little real discussion of alternatives to those 2 particular mixes over there. They'll also do fine in most any commercial soil-less potting mix. It's really pretty much up to you. I would avoid anything that includes a coir component however.