In blueberry plants, root and shoot growth occur in flushes throughout the growing season. Apparently, there is a cycling pattern between root and shoot growth during summer, but these cycles are not absolute.
Two major flushes of shoot and root growth have been observed for northern highbush blueberries with the first flush of root growth occurring during leaf bud swell, bloom and fruit set, and then gradually diminishing and continuing at a low level until after fruit harvest. The second flush of root growth was initiated in mid-August and continued through September, during the period of flower bud initiation and before the onset of dormancy.
Leaf and shoot growth/budbreak that occurs before, during or after floral budbreak, depending on particular species and/or cultivar, has been observed. In Rhode Island conditions, the first flush of shoot growth in northern highbush blueberry peaked about 30 to 70 days after bloom, which coincides with the seed growth stage of fruit development. A second shoot growth flush was observed after fruit harvest.
Most likely, rabbiteye and southern highbush blueberries may exhibit more than two flushes of shoot and root growth because of the longer growing season in the southeastern United States.