ABOUT MULBERRIES:Morus spp.
Moraceae
Relatives: Fig, Banyan, Breadfruit, Jackfruit, Osage Orange
Mulberries are large, fruiting deciduous trees which can grow up to 40 feet tall and are highly attractive to both humans and wildlife. There are three main species in common cultivation: Morus alba and Morus nigra, both native to Asia and the Middle East, and Morus rubra, native to North America.
DESCRIPTION
Mulberry plants come in many different forms: multi-stemmed shrubs or single-stemmed trees, up to 40’ tall or as small as 10’ – 12’, separate male-flowered and female-flowered trees or self-pollinating trees, upright or weeping, fruiting or ornamental.
LEAVES: Mulberry leaves are large and heart-shaped with serrated edges, and come in many shades of green. The leaves of M. alba cultivars are the only food that silkworms will eat, and they must be fresh as silkworms do not drink and only get what moisture is contained in the leaves. The leaves are also used to make mulberry tea, and can be used with the bark to make natural dyes. Mulberry tea has traditionally been used to treat stomachache, coughs, and colds.
FLOWERS: The flowers are small and inconspicuous on most cultivars. Some species are dioecious, meaning each tree will only grow either male or female flowers, requiring two trees near each other for pollination. Other species are monoecious, meaning they produce both male and female flowers on the same tree. Most commercially available mulberries are monoecious. The male flowers grow on catkins usually 1-2 inches long, similar to what you might see on a pecan or birch tree. The female catkins are half that size with smaller flowers.
FRUIT: Mulberries, like many other fruits in the Moraceae family, are considered a multiple or collective fruit, meaning that a single fruit grows from multiple flowers. Each female catkin grows a cluster of flowers – or inflorescence – which are individually pollinated and develop separate fruits in each ovary, but as the fruits mature they merge into a single mass. Two other very popular collective fruits are figs and pineapples!
The fruits vary in size, shape, and color depending on the species and cultivar. The smallest fruits can resemble blackberries in appearance, while the largest can reach 2-3 inches in length. The ripe mulberries may be red, purple, black, pink, or white. Fruit from the M. rubra species have an excellent flavor, while the M. alba fruits are very sweet but less flavorful, but the fruit from M. nigra species are considered to have the best quality overall.
CULTIVATION
LOCATION: Mulberries have a very wide growing range and are very adaptable trees, making them an excellent choice for many growers. They will grow best in full sun but will also tolerate part shade and are wind tolerant. Mulberries should be grown away from pavement and buildings, as they have large shallow roots which can cause damage over time. Additionally, the highly pigmented fruit is likely to stain any surface they drop on (or are “dropped” by the birds which love to eat them).
TEMPERATURE: Mulberry trees are hardy down to USDA Zone 5, about -20° F, but with their low chill requirements can also be grown as evergreen trees in warmer climates.
CHILLING: Chilling refers to the number of hours, 45 degrees F and under, during the dormancy period. All fruit and nut trees need a specific amount of chilling hours before they will produce fruit. Mulberries are a low-chill fruit, and most cultivars only require 200 – 400 chill hours.
SOIL/WATER/NUTRIENTS: Mulberries will grow best in well drained loamy soils, but can thrive in coarse or sandy soils. They are drought tolerant and need little to no irrigation or fertilizing once the roots are established.
PRUNING: Many species of Mulberry will naturally grow in a multi-stemmed shrub-like habit, but can be pruned and shaped into a single-stemmed tree. They have low branches which can be removed to protect the limbs from damage. They are also an excellent species for renewable forestry techniques such as coppicing, in which a tree is cut down near the base which encourages vigorous shoot growth from the stumps. Those shoots can then be thinned and selected for the most desirable wood, which is allowed to grow to size before being harvested and encouraging more shoot growth in turn. Any heavy pruning should always be done in the winter months when the tree is dormant, as mulberries can be slow to callous and the cuts can lose too much sap or introduce disease if they’re made when the weather is too warm.
PESTS AND DISEASES: Mulberries are resistant to most common pests and diseases, but not invulnerable. Whiteflies, mealybugs, and scale are uncommon but can spread to mulberries from other infected plants. They can develop root rot if grown in an area without adequate drainage. As stated above, wounds or damage to mulberry trees can be slow to heal, leaving an easy entry point for fungal or bacterial diseases if not treated with some form of tree wound sealer.