Go to walmart, buy some 2 cuft bags of the new green bagged hyponex soil (some good soil I found so far). Or get what ever bagged potting mix you like. Get it home, open bag, and plant. Potting mix has a larger buffer for ph and nutrients than soilless media. Soilless media can produce more yield, but it has its disadvantages. Both have some advantages and some disadvantges. To say there are NO disadvantages to one in particular would be speaking in absolutes. ;) This post was edited by TheMasterGardener1 on Mon, Feb 25, 13 at 13:58

Check out the earthtainer construcion guide for some mix info for a self watering planter, or just search container mix. Most will be a soil-less mix, there are a ton of great threads on here regarding container mixes, fertilization, and also water movement/retention. The poster above "Al" has some very informative and detailed explanations. It seems like gardening is such a varied and expansive topic that searches very rarely yield a simple, direct clear answer to a question. The answers I have found have been partly from searches, partly from posting a question, and partly from reading older posts ( sometimes not directly related to my original question ). There is an enormous wealth of knowledge here, take advantage of it, I did and have learned alot.

Andrew: I think people new to these mixes always overestimate how quickly they dry out and scare themselves about how often they will have to water. Most inexperienced growers water too often as it is. I have many large plants growing in gritty mix inside during the winter that can go two or three weeks between waterings. Even my most demanding plants in smaller containers of gritty don't usually need to be watered more than once or twice a week. And, I find the 5-1-1 needs about the same amount of watering that the better quality store bought mixes I’ve used in the past--like Promix and Fafards--do. You have a pretty large and varied plant collection that ranges from the sanseveria, which I have found impossible to kill, to the azalea "bonsai," which I don't think anyone but a bonsai master could keep alive indoors over the winter. (I did keep one alive for one fall and winter by carrying it from microclimate to microclimate inside and out, sometimes twice a day. Not worth it.) And maintaining a Japanese maple or juniper over winter is a different kettle of fish. But, I’ll throw in my 2 cents on maintaining houseplants over the winter in Michigan in hopes that someone else will add theirs. On your specific questions: 1. Substitution: The size of the components is the most important consideration. For gritty mix, you want all ingredients between about 1/8 inch and 3/8 inch in diameter. For 5-1-1, you want all ingredients at 3/8 inch or smaller. Secondly, I wouldn't try to substitute for the pine/fir bark in either mix. The gritty mix is one-third bark and the 5-1-1 is 70 % bark, and I think that is the most important ingredient in both mixes. In gritty mix, you can substitute an inert substance that is not absorbent for the granite, and one that holds some water for the Turface. Perlite would do for either, although it is closer to Turface in its behavior because it does hold a lot of water on its surface. If you want the gritty mix to hold a little more water, it would be better to increase the Turface or floor dry and reduce the grit than to use ingredients smaller than 1/8 inch. Used indoors, I don't think you want the 5-1-1 to be any more water retentive than it already is. When I use 5-1-1 outdoors for summer vegetables, I substitute Turface or NAPA floor dry for the perlite and substitute compost for some of the peat to increase its water holding capability. 2. What do you do with the screened out material? I add the stuff I sift out of gritty mix to my 5-1-1, or I add it to my outside beds. 3. Personally, I don't spend anywhere near the amount time and effort many others use on screening materials for the gritty mix. And I don't screen materials for the 5-1-1 at all. I just rinse the dust off the granite grit and only rapidly sift the Turface and bark over insect screen for the gritty mix. If I were growing more picky plants or bonsai in very small containers, I would spend a lot more effort on this. (I would use 5-1-1 for your gardenia and azalea since they both like moister soil.) Most of my plants are in one-gallon pots or larger, so I don't worry about it. 4. Sapwood comes from the wood under the bark of the tree and is fairly easy to spot if you have a good source of pine bark. It usually is a lighter color and can be easily splintered into straight pieces, unlike bark chips which are hard to break up. Just take out the obvious stuff. If your bark has up to about 5 percent sapwood mixed in, it will be OK.

If the worms are happy the soil is healthy. That being said I would still amend it with some fresh potting soil. It will ensure that the worms will continue to have something to eat which in turn will feed your plants.