Both attractive and useful, blueberries (Vaccinium spp.) provide fruit as well as an impressive display in fall. Your climate dictates the type that will grow best for you, either highbush blueberries (Vaccinium corymbosum), which grow in U.S. Department of Agriculture plant hardiness zones 3 through 7 or 8, or rabbiteye blueberries (Vaccinium asheii), which grow in USDA zones 7 or 8 through 9, depending on variety. Hybrids may push the limits of those zones. All have similar cultural requirements, including well-draining soil with a low pH and full sun or light shade. Good companion plants share those requirements.
Blueberry bushes make good companions for other species of fruiting shrubs. These include red raspberry varieties like "Heritage" (Rubus idaeus "Heritage"), which grows in USDA zones 4 through 8 and American highbush cranberry (Viburnum opulus var americanus), which grows in USDA zones 2 through 7. Cranberry and blueberry are native to similar moist, free-draining areas, which suit raspberries as well. The three shrubs may flower and fruit in light shade, but do best in full sun. All thrive in soil that falls below 7 on the pH scale. Cranberry and blueberry complement each other with bright fall leaves.
Vegetable Garden Companions
In a sunny vegetable garden, blueberry bushes might be used as a shrub boundary or placed in the corners of square plots. Many garden vegetables make good blueberry companions because they thrive best in soil with a lower pH and full sun. Tomatoes (Lycopersicon esculentum) are most prominent among this group. Other possibilities for vegetable garden companions include various varieties of peppers (Capsicum annuum) eggplant (Solanum melangena) and annual okra (Abelmoschus esculentus).
Blueberries make natural companions for other plants in the heather family. Underplant the bushes with Scotch heather (Calluna vulgaris), which grows in USDA zones 4 through 6 and native to conditions almost identical to blueberry. For all-season interest, pair blueberry with its evergreen relative andromeda (Pieris japonica), which features similar bell-shaped flowers, Growing in USDA zones 5 through 8, the acid-loving shrub also flourishes in sun to part shade. For blueberries in part shade, pair with rhododendrons, like the hybrids in the PJM Group (Rhododendron PJM Group), which grow in USDA zones 4 through 8.
Blueberry Landscape Considerations
Before planting blueberries or suitable companion plants it is a good idea to test your soil's pH. To do so, use a home test kit or pH probe. If the soil pH is high, it can be lowered by adding an acidifier, such as an organic supplement containing 30 percent sulfur. Wear gloves and follow package directions. For blueberries, apply in spring, spreading 2 1/2 cups of acidifier around each established plant, spreading it out as far as the circumference of the widest part of the plant. Water thoroughly and repeat every two months until a soil test shows the desired pH.