Most mulberry trees (Morus spp.) are large, growing 30 to 80 feet tall, depending on the species. Dwarf mulberry cultivars can be kept to a more compact size that's more in keeping with the "mulberry bush" name from the children's song.
Three mulberry species grow in the U.S., but only one is native to North America.
Red mulberry (Morus rubra) is native to the eastern U.S., and it grows in U.S. Department of Agriculture plant hardiness zones 4 through 8. It typically grows to 35 and 40 feet tall, but in ideal conditions and with organically rich soil, it may grow up to 70 feet tall.
White mulberry (Morus alba) originates in China, and it also grows in USDA zones 4 through 8. It is potentially the largest of the three species, sometimes reaching heights of 80 feet, but white mulberry cultivars vary widely in size and growth habit.
Black mulberry (Morus nigra) is a native of western Asia, and it is generally the smallest of the three species. It typically reaches about 30 feet tall, and its growth habit tends to be bushy if it's not trained to be a single-trunked tree. It is also the least cold hardy of the mulberry species, growing in USDA zones 5 through 9, but it may have trouble in climates colder than USDA zone 7.
Mulberry fruits are not technically berries, but rather a compound fruit made up of many tiny, fleshy segments called drupelets. Despite the names of the mulberries species, the color of the fruit can vary even within a species; white mulberries, for example, can produce purple or red fruits, and red mulberry fruits may be a dark red that is nearly black.
Of the three species, black mulberry produces the fruit that's generally considered to be most flavorful.
Several mulberry cultivars remain small enough that you could call them bushes.
The 'Dwarf Everbearing' (Morus nigra 'Dwarf Everbearing') variety of black mulberry, which grows in USDA zones 5 through 10, remains extremely compact, between 2 and 6 feet tall, and it is small enough to grow in a container. Given enough warmth and sun, it produces fruit throughout the growing season.
Some small varieties of white mulberry have unusual growth habits that make them attractive garden specimen plants.
- The 'Unryu' cultivar (Morus alba 'Unryo') has twisting, contorted branches. It can reach 30 to 40 feet, but it can be trained to remain in a bush form with a height between 8 and 15 feet. It's hardy in USDA zones 4 through 8.
- 'Chaparral' (Morus alba 'Chaparral') is a compact cultivar with a weeping growth habit. It grows to between 6 and 8 feet tall. It's hardy in USDA zones 4 through 8.
- 'Pendula' (Morus alba 'Pendula') is a female weeping mulberry that doesn't produce fruit. It's hardy in USDA zones 4 through 8.