Mulberry trees, belonging to the genus Morus, are cultivated globally for their sweet, edible fruit and dense canopy that provides shade. Determining the final height of a mulberry tree is not straightforward, as growth is highly variable. The ultimate size depends entirely on the specific species planted and the cultivation methods used to manage its shape.
Species Determine the Size
The most significant factor influencing a mulberry tree’s height is its species, with the three most common varieties displaying distinct size differences. The native North American Red Mulberry, Morus rubra, tends to be the tallest of the group. Under ideal conditions, this species often reaches mature heights between 35 and 50 feet, though exceptional specimens can grow up to 70 feet or more.
The White Mulberry, Morus alba, originally from China, is also a tall tree, typically maturing between 33 and 66 feet tall. This fast-growing species offers rapid shade. However, it is known to hybridize with the native red mulberry and can be considered invasive in some regions of the United States.
In contrast, the Black Mulberry, Morus nigra, is generally the most compact and slowest-growing species. It usually reaches a mature height of 20 to 40 feet, often presenting a more shrub-like, broad canopy. This size makes it a preferred choice for fruit production in smaller spaces, as the fruit is considered superior in flavor.
Beyond the main species, specialized cultivars are intentionally bred to remain small. Specific varieties like ‘Gerardi’ are considered true genetic dwarfs, naturally limiting their height to under 15 feet. Weeping forms and other fruitless varieties often stay in the 6- to 10-foot range, making them suitable for ornamental use or container growing.
Managing Height for Home Gardens
For many home growers, the natural height potential of larger mulberry species requires active management to keep the tree small. One effective method to restrict vertical growth is pollarding. This technique involves making an initial severe cut to the main trunk and branches at a desired height, followed by the annual removal of all new vertical growth back to the original cut point. Over time, this repeated cutting creates a distinctive, knobby structure, maintaining the tree at a consistent, reduced height.
A similar practice, known as coppicing, involves cutting the tree down close to the ground to encourage multiple new shoots. These shoots can be harvested for leaf fodder or wood, keeping the plant bush-like. Both pollarding and coppicing are well-tolerated by the vigorous mulberry species and keep the fruit and leaves within easy reach.
Cultivators also control size from the start by grafting the tree onto a specific rootstock, which controls the overall size and vigor. While true dwarfing mulberry rootstocks are uncommon, using genetic dwarf varieties as the scion, or upper fruiting portion, achieves the same result. Growing any mulberry in a large container or pot naturally restricts the tree’s growth by limiting the root zone, which stunts the overall height.
Growth Rate and Maturity
Mulberry trees are categorized as fast-growing, especially during their juvenile period. The White Mulberry is the most vigorous, often adding three to five feet of growth annually in favorable conditions. The Red Mulberry typically increases its height by two to four feet each year. The Black Mulberry grows at the slowest pace, usually gaining only one to three feet of height per year.
Mulberry trees can reach functional height and begin producing fruit quickly, sometimes in just one or two seasons for grafted plants. However, attaining the maximum mature height takes a longer time. While mulberries are often cited as reaching maturity in 10 to 15 years, reaching the maximum size potential usually requires decades of growth.