I am new to this site, and do not have a PDC, so maybe take this as a comment from beginner's eyes. But I do have some experience with the blubes. It seems to me that this thread began with a challenge posed more by an initial monocropping approach. Where I just moved from, and where I have some experience, blubes thrive naturally in wooded or savanna type communities with lots of natural, highly acidic mulch (oak leaves and pine straw). On the farm there, the blueberry monocrop is in former forest soil with heavy mulching of this same mix. The successful companion plants would seem, therefor to be the oaks and pines. not ground cover. As the bushes have matured, they shade out the grass themselves. I am looking at blubes for the farm I am on now. Have natural 4.5-5.5 soil, lots of riparian areas with heavy foliage, and so am looking to establish them in the moist soils (remember:no root hairs -> constant soil moisture requirement). The only other companion I am looking for would be a low-bush azalea of some kind that could provide annual foliage and compatible microbe/fungal community.