The size a blueberry bush ultimately reaches depends entirely on its genetic makeup, as all blueberries belong to the genus Vaccinium but are divided into distinct groups. The potential height and width are predetermined by the specific type you choose to plant. Variation is significant, ranging from low-lying groundcovers barely reaching a foot to multi-stemmed shrubs that can exceed ten feet.
The Primary Size Categories
The tallest varieties are the Northern Highbush blueberries, which are responsible for the majority of commercial production across North America. These upright, multi-stemmed shrubs typically mature between six and twelve feet tall, with a comparable spread of six to eight feet wide. Cultivars within this group are naturally large plants that require substantial space.
A close relative, the Southern Highbush, is a hybrid developed for regions with milder winters and warmer climates. While genetically similar to their northern counterparts, their mature size tends to be slightly more variable, often reaching a height of four to thirteen feet and a width of three to ten feet. This group is generally considered to be in the same large-shrub category as the Northern Highbush.
The next major category is the Rabbiteye blueberry, a species native to the southeastern United States that is notably more heat- and drought-tolerant than the Highbush types. Rabbiteye bushes grow vigorously, commonly reaching six to ten feet tall. They possess a distinctive growth habit, often becoming wider and more robustly branched than Highbush varieties, sometimes spreading up to six to ten feet.
For smaller spaces, the Half-High blueberries offer a compact solution, as they are a genetic cross between the tall Highbush and the low-growing wild varieties. These hybrids are intentionally bred for cold hardiness and a manageable size, generally maturing at an intermediate height of two to four feet. Their compact nature makes them excellent candidates for patio containers or small garden beds, providing good fruit yield without the massive scale of the Highbush types.
At the lowest end of the size spectrum is the Lowbush blueberry, often referred to as wild blueberry, which is a true groundcover. These plants spread primarily through underground runners, forming dense mats that rarely exceed six inches to two feet in height. This low-profile growth habit makes them a unique choice for landscaping where a traditional tall shrub is not desired.
Environmental Factors Influencing Final Dimensions
While genetic type sets the potential size range, external growing conditions determine whether a blueberry bush reaches the maximum or minimum of that range.
Soil Acidity
The most significant environmental factor is the soil’s acidity, which must fall within a tight range of pH 4.5 to 5.5 for optimal growth. If the soil pH is too high, the bush cannot properly absorb iron and other micronutrients, leading to a condition called chlorosis. This condition severely stunts the plant’s growth and reduces its overall mature size.
Sunlight Exposure
Sunlight exposure is another factor directly related to a plant’s vigor and density. Blueberry bushes require at least six hours of direct sunlight daily to maximize photosynthesis, resulting in a taller, more robust bush. Plants grown in partial shade will survive but often have a spindly, less dense habit and fail to reach their full potential height.
Consistent Moisture
Consistent moisture is necessary because blueberry bushes possess a shallow, fibrous root system that is highly sensitive to fluctuations in water availability. The soil must be moist but also perfectly well-drained. Soggy, waterlogged conditions can lead to root rot, which quickly diminishes the plant’s health and stunts its growth.
Climate Suitability
Climate suitability also plays a role, especially the requirement for “chill hours,” which are the cumulative hours below 45°F needed for the plant to properly emerge from dormancy. If a Northern Highbush is planted in a warm region with insufficient chill, it will exhibit poor vigor and delayed, stunted growth. Conversely, a low-chill Southern Highbush planted in an extremely cold climate may suffer from freeze damage, preventing it from reaching its expected mature height.
Techniques for Managing and Controlling Bush Size
Gardeners can actively manage a blueberry bush’s size through intentional intervention, regardless of its genetic potential.
Renewal Pruning
Renewal pruning is the primary method used to control both height and width in Highbush and Rabbiteye varieties. This technique involves removing a percentage of the oldest, thickest canes, typically one-fifth of the total, right down to the ground in late winter. This removal stimulates the growth of new, younger canes, which are more productive and helps to keep the overall height and spread within a desired, manageable limit.
Container Growing
For severe size restriction, growing the bush in a container is an effective physical control method. Confining the root system within a pot limits the plant’s ability to draw nutrients and water, which naturally stunts its overall vegetative growth. This allows a gardener to successfully grow a variety that would otherwise become too large for the available space.
Planting Spacing
The initial spacing chosen at planting time directly influences the mature width of the bush. Planting Highbush varieties five feet apart may result in a dense, continuous hedge as the canopies merge. To allow a bush to reach its maximum natural spread and maintain an individual, distinct shape, planting distances must account for the full mature width of the selected variety.