Mulberry trees (Morus) are popular deciduous landscape additions, valued for their quick-forming shade canopy and prolific fruit production. They are known for their vigorous nature and adaptability to a wide range of climates. Most mulberry varieties are categorized as fast to very fast growers, making them a compelling choice for those seeking a mature tree relatively quickly.
Defining the Growth Rate
Growth for most tree species is classified by the average vertical height gained each year. A mulberry tree is typically categorized as fast-growing, adding an average of 2 to 3 feet of vertical height annually once established. This rate is significantly faster than many common ornamental or fruit trees, which often average only 1 foot per year.
Under optimal conditions, young mulberry trees in their juvenile stage can experience surges, potentially exceeding 4 or 5 feet of growth in a single year. This initial vigor allows the tree to establish a strong structure and root system rapidly. However, this pace slows as the tree reaches maturity, with older specimens typically adding less than one foot of height per year.
Species Differences in Growth
The speed at which a mulberry tree grows is highly dependent on its specific species and genetic differences. The White Mulberry (Morus alba) is the fastest and most aggressive grower within the genus. This adaptable species, originally from Asia, quickly becomes a large specimen, often adding 3 to 5 feet of growth per season.
The native Red Mulberry (Morus rubra) also demonstrates a fast growth rate, though it is slightly less aggressive than the White Mulberry. Many popular, high-yielding cultivars are hybrids of these two species, combining the hardiness of the red with the vigor of the white.
In contrast, the Black Mulberry (Morus nigra) is the slowest growing of the three primary types. Although revered for its superior fruit flavor and longevity, this species typically only adds between 1 and 2 feet of growth annually. Additionally, specialized dwarf varieties are bred for contained growth, often limiting their annual vertical gain to a foot or less.
Environmental Factors Influencing Speed
While genetics set the potential, external factors determine the actual growth speed. Sunlight is a primary driver; mulberries maximize growth when situated in full sun, receiving at least six to eight hours of direct light daily. Although they tolerate partial shade, insufficient light significantly reduces both the growth rate and fruit production.
Consistent water availability is another contributor to accelerated growth, especially in younger trees. Although mulberries are drought-tolerant once mature, a reliable moisture supply in well-drained, fertile soil promotes the fastest development. Trees planted in poor, compacted, or nutrient-deficient soil will grow more slowly as they struggle to establish a robust system. Furthermore, growth will slow dramatically, or even cease, in regions that experience prolonged, severe cold temperatures.
Managing Rapid Growth
The rapid growth of the mulberry tree requires management to maintain a desired size and shape, especially in smaller landscapes. Pruning is the most effective tool for controlling the tree’s vigor and redirecting its energy. Techniques like pollarding involve annually cutting back all new growth to a permanent framework of scaffold branches, a traditional method for keeping the tree small and maximizing new, fruitful growth.
Regular thinning cuts help open the canopy to air and light by removing dead, diseased, or crossing branches. Pruning is best performed during the late winter dormancy period before new growth begins, which minimizes the substantial sap “bleeding” mulberries are prone to. For fruit production, yearly pruning is often needed to keep the harvest within easy reach.
Careful consideration of placement is necessary to avoid future conflicts with infrastructure due to their quick establishment and eventual large size. Mulberry trees should be planted a sufficient distance from foundations, walkways, and utility lines, as their fast-growing nature is accompanied by a substantial root system. Proactive maintenance ensures the tree remains a manageable and productive part of the landscape.