The reason(s) amending of soils in small areas is counterproductive do not vary with the type of soil. Sandy, silty or clay-like, it makes no difference. You do not want to install plants in pockets, strips or zones of one soil texture surrounded by soil of a different texture, as this sets them up for likely problems with how water moves into and out of the soil around their roots. In the case of plants to be left in place for many years (or indefinitely) without lifting and re-planting there is no point in incorporating organic soil texture modification materials (bark, compost, peat...) even if the bed is large enough to minimize or eliminate water movement problems for most of the plants - once the amendments decompose the effects they produce will be lost. Inorganic amendments like perlite and sand do not decompose but enormous amounts of these have to be added to change a heavy soil into a light one. And if too much is added then a droughty and infertile (leaching) situation may be produced, that may be more limiting than a heavy clay-like soil. The most straightforward approach is to choose plants adapted to the existing soil type and plant these in wide, shallow holes dug out of that, loosening it over a wide area beforehand and mulching well afterward. The most satisfactory mulch for woody plants appears to be clean wood chips. If arborist wood chips available nearby tend to have bramble stem sections or other undesirable material mixed in then play chips from a local dealer may be the best bet. Ones we obtain here as cedar play chips are very nice but have become quite pricey, as far as it goes.

I'm not in SC, but am also in zone 7, and have tried (or have) all the plants you note: Bush cherry - nanking grows well; for some reason last year mine had no fruit (insufficient chilling?), so I dug it up & moved it in the back yard - threw some dirt around the roots in the winter, and it is doing well. goji (and wolfberry) seem to be doing well; like a fish emulsion (at least to start). Not a whole lot of berries so far, but some. No disease problems. Pineapple guava-died this past winter (2nd year). So hardiness is a concern. Northstar cherry-good for a few years, stopped spraying, then the tree turned green & died. Goumi-excellent choice. Self-pollinating(no matter what they say, I only have one & it has lots of fruit). My opinion is you (generally, possible exception is trebizond date) can't miss with an elaegnus (autumn olive, goumi, sea buckthorn-sea buckthorn, you really should consider it if you are also considering goji). I have 4 blueberry plants (northern highbush, but have often wondered if I should try rabbiteye) that are doing well, as long as you have the soil right, blueberries are great. Maybe you'd also like to consider something more prosaic-blackberries & raspberries (blackcaps especially, for me anyway) work.

There should be a wholesale florist in either Greenville or in Spartanburg - try there. Ask your local florist, if you can't find any other source - but I know it is possible to buy large boxes of clippings of boxwood for decoration, so would imagine that boxes of fir branches should be available.... As Tamelask says, try the nearby X-mas tree places - they do trim up the trees to suit the customer, and have to do something with the off-cuts - there might be a small charge for them, depending on the source...

Cherry of the Rio Grande, Barbados Cherry, Dwarf Bananas (many varieties), Sugar Apples, Atemoyas, Jaboticaba (very slow-growing), Miracle Fruit, Dwarf Mangoes (many varieties), Wurtz Avocado, Pitomba, Papaya (many varieties), Coffee, Dwarf Mulberry, Figs, Cashew- these are some I grow, and all are under 10' tall, and producing. I also grow low-chill Apples, Plums, Peaches, Nectarines, Pears, Blueberries, Blackberries and Grapes. They are all kept small for easy care. A very interesting cactus with lovely fruits are the Pitayas, or Dragonfruit. They are usually grown on a pole that has support at the top so they can arc downward. Easy to keep under 10' tall. I'm sure I've forgotten some plants, but the above list should get you started(G). Lisa