Mulberries (Morus spp.) are not typically small plants. While you can train any tree to stay small with assiduous attention to pruning, be aware that if you decide to grow mulberry, you will need to prune it every year to control its height. If you're a busy mom, then the constant pruning may be more than you want to tackle, and even then you might not be able to keep it small.
The white mulberry (Morus alba) hails from China, the red mulberry (Morus rubra) is native to the eastern United States and the black mulberry (Morus nigra) to western Asia, where it was grown in Roman times. All three are deciduous shrubs. While the red and white mulberries grow best in U.S. Department of Agriculture plant hardiness zones 4 through 8, black mulberry is not nearly as cold tolerant. It is usually limited to USDA zones 7 and above.
Mulberries can grow tall. While red and white mulberries generally top out between 30 and 50 feet, they are capable of greater heights -- 80 feet for the white mulberry and 70 feet for the red. The black mulberry is the smallest of the three, growing to only 30 feet and displaying a bushy habit when untrained. If you want to keep these trees small, prune them starting when they are young and continue to remove height every year.
The mulberry is susceptible to bleeding; its sap leaks profusely from the cuts you create with clippers or pruning shears. This is less of a problem when the plant is dormant in late fall or winter, so prune then to minimize sap loss. If you prune a branch that is more than 2 inches across at any time of year, the sap loss is severe.
If you let a mulberry go, do not try a hard prune to make it smaller. When pruning, you mustn't cut branches that are wider than 2 inches or you'll harm the tree. Remove excess branches to create a strong, open structure, removing branches that grow upward and encourage those that branch out. Be careful when pruning, as shears and clippers are dangerous. Children should not use them until they are old enough to understand how they work.
Mulberry is not a deadly plant. However, ingesting the unripe berries and the sap from broken stems or branches can cause an upset stomach as well as hallucinations, which can be unpleasant. Warn children to stay away from these berries until they are ripe, displaying the characteristic dark, black color. Also warn them that the sap is never a good thing to put in their mouths. If you have small children who can’t understand or curious pets, keep them away entirely.