To extend the garden or just add beauty around the blueberry plants one can plant vegetables. These include underplanting lettuce, onion, and spinach while also planting bush beans along side blueberries. These plants not only work with blueberries, but the harvesting of any of the fruit or produce will not interfere with fruit production.
Pine and rhododendron are both plants that require an acidic environment to grow which works perfectly with blueberries. The pine needles that are dropped throughout the season can be used as a mulch for blueberry plants, which helps keep the pH at 4.5-5.0. This benefit keeps these shrubs, trees, and blueberries happy. But remember that blueberries are shrubs that can tolerate being planted as an understory plant in conjunction with pines.
Flowers add beauty to the flower garden but can also add texture and variety around the blueberries. Plants such as creeping phlox and lily of the valley are good choices for companion plantings with blueberries. They both tolerate the pH level well and provide color different times of the growing season.