Any well draining soil should work.

The most important thing is not to overfertilize them if you want them to remain small, and give them plenty of light so they don't stretch. Don't overpot them either, meaning no larger than a 6" pot for a grouping of three ampullacea or similar types.

hi,

i would make 3 plants in a 8 inches (20cm) pot, with pine bark and maybe i mulching the top with spaghnum.

i have some pics from ampullacea and punctatissima and she look very great and compact. i think mother plants are a little bit stretched but the other looking compact.