Mulberries are a fruitful crop to grow in Maine, but plan their placement carefully so that the berries don’t stain walkways, entryways, decks, etc. Illustration from Handbook of Plant and Floral Ornament from Early Herbals, by Richard G. Hatton, Dover Publications, N.Y., 1960.
By Roberta Bailey
As a child I knew where every ripening fruit and berry grew, and I watched for them to ripen, eating a lot of unripe fruit in anticipation. Other than peaches, mulberries were the center of my attention. Not content with waiting for the berries to drop, I learned to climb trees to get to the first ripe fruits. I would fill a little purse with them and eat them throughout the day. My mouth, hands and knees, and, I imagine, my clothes, were stained purple for most of the summer. I thank my mother for the freedom to climb and eat with abandon. I am still up in the trees chasing the best of the fruit. Mulberries remain my passion.
The Big Trees Are Worth Growing
Mulberries are members of the Moraceae family, which includes the fig, breadfruit and sassafras trees. A few species are bushes, as mentioned in the nursery rhyme, but the fruit-bearing species worth growing are large trees. Of those, Morus alba, white mulberry, and M. nigra, black mulberry, are native to China. Morus rubra, red mulberry, is a North American species, ranging from the mid-Atlantic to Florida and west to Nebraska and Texas. Morus nigra is cultivated throughout Europe for its large, sweet-tart fruit. Morus alba is the hardiest, surviving –25F. and colder, though its fruit quality varies greatly.
The genus name Morus is derived from the Latin ‘mora,’ which means ‘delay,’ and refers to the late leafing habit of the mulberry. Many a year I have been sadly convinced that my mulberry did not survive the winter, only to have it bud and leaf in late spring. This delay ensures that its fruit buds appear well after danger of frost has passed. If you can get a tree to live in your area, it will likely fruit reliably every year. As this article focuses on the Northeast, all information will be for M. alba.
Mulberries are 30- to 50-foot, fast growing, long-lived deciduous trees with alternate, simple, lobed to undivided leaves. Leaves on one tree can be lobed and unlobed. Though both monoecious (male and female flowers on one plant) and dioecious (male and female flowers on separate plants), many trees are self-pollinating. Trees are also known to change sex. The tree flowers inconspicuously in late spring on the current season’s wood and on spurs of old wood.
Fruits, which ripen in midsummer, are small fleshy drupes, resembling a tightly beaded blackberry. Fruit color ranges from white to lavender to red and purplish-black. Some mulberries are seeded, though I have known over two dozen trees and never met a seed. The flavor is mild and very sweet, but M. alba is said to lack the perfect blend of sweetness and tartness of M. nigra. I have tasted only M. alba and love it. If I need the tartness for any reason, I mix in some under-ripe fruits. As I noted before, beware: The dark fruit stains badly.
Selecting a Cultivar
Morus alba was brought to North America in hopes of creating a thriving silk trade; mulberry leaves are the main diet of the silk worm. Between the 1600s and the mid-1800s, the silk industry rose and collapsed, but M. alba readily adapted to its new habitat and crossed with the native M. rubra as well. From these silk plantings came a few select cultivars. ‘Downing,’ the first and most famous, was selected for its excellent flavor. ‘Illinois Everbearing’ was a later M. alba x M. rubra hybrid; it is now known for its large, sweet fruit and exceptional hardiness.
When buying a mulberry tree for fruit, choose a cultivar that is very hardy, self-fruitful and has good, seedless fruits. If the catalog or nursery does not specify, be sure to ask, since many fruitless and weeping cultivars are available. If a mulberry tree grows in your area, it can be propagated by hardwood or softwood cuttings and grafting. A good book on plant propagation will detail these techniques.
Planting and Tending
Mulberries prefer a well-drained, fertile soil and tolerate any conditions except wet soils. They withstand drought and salt conditions, making them a good urban or seaside planting. They do best with full sun but tolerate light shade. Allow a space of 25 to 30 feet around each tree.
Because the dark fruits stain badly, avoid planting mulberries near walkways and driveways or where fruit will be tracked into a dwelling. Keep in mind that the branches can be brittle. Trees can be planted to overhang a chicken yard. Chickens, turkeys and pigs are very fond of mulberries. Herbaceous fish also like them.
Once you have the perfect location, dig a bushel-sized hole and place the tree in the hole. Spread the roots if possible. Return the topsoil to the bottom of the hole, covering the lower roots. Then mix 4 to 8 quarts of compost with the remaining soil that you dug from the hole, and return that to the planting hole. Be sure to tamp the soil lightly as you add it, to get rid of air pockets around the roots. Adding water when the hole is half filled with soil and again when the hole is full will help settle the soil and remove air pockets. When the hole is full, form a rimmed “bowl” of soil around the tree and water thoroughly. The bowl helps hold the water around the tree. Water the tree once a week throughout the first year, unless it receives an inch of rain per week. Mulch at least 2 feet out around the tree trunk to reduce grass competition. Mulberries are fast growing and need little fertilizer.
Prune trees to establish a healthy branching structure, free of narrow crotches or too many branches close together. Once the structure is established, little pruning is needed. Branches can be kept short to prevent wind or weather damage.
An Abundant Harvest
In New England, mulberries ripen in early summer, usually over a two- to four-week period. A mature tree can produce up to 10 bushels of fruit – enough for you and for the birds that will flock to the tree. Mulberries are sometimes used as a decoy for crops such as sweet and sour cherries and raspberries. The fruit fill out and soften, then drop. Hand pick the fruit or spread a sheet under the tree and shake the tree so that the ripe fruit will fall.
Fruit are delicious eaten fresh. As they ripen over many weeks, you can eat them every day for breakfast or dessert. Mulberries are also made into pies, tarts, jellies, syrups, marmalade, juice and wine. They can be dried and used as a snack, or in puddings or oatmeal cookies and muffins. Mulberries and elder flowers are traditionally combined with other herbs to produce a kombucha drink having champagne-like qualities.
As well as the fruit, the young shoots can be steamed and eaten with rice or in stews or brewed into teas. Mulberry wood barrels are used to age balsamic vinegar.
Mulberries seem to have few problems in the North other than winter damage. Young trees can be susceptible to scale or cankers; cankers should be cut off and burned. Older trees are less affected. Fruits can get ‘popcorn’ disease where the berries blow up to look like popped corn. Since the disease perpetuates and overwinters in the fruit, the best prevention is to gather and destroy affected fruits.
Hardy varieties are available from northern nurseries every few years. ‘Illinois Everbearing’ is commonly available from many nurseries. It has sweet purple fruit and is hardy to –25 degrees F. St. Lawrence Nursery in Potsdam, N.Y. (www.sln.potsdam.ny.us), offers ‘Nothrop’ every few years; this is a sweet-fruited, very hardy cultivar. Fedco Trees in Waterville, Maine, will offer Super Chilly mulberry in 2004, another M. alba with sweet, seedless fruit and exceptional hardiness. All are self-pollinating.
Dirr, Michael, Manual of Woody Landscape Plants, Stipes Publishing Co.. 1990.
Facciola, Stephen, Cornucopia II – A Sourcebook of Edible Plants, Kampong Publishing, 1998.
Hill, Lewis, Pruning Simplified, Storey Publishing, 1986.
Holmes, Richard, Sally Roth and Frances Tenenbaum, editors, Taylor’s Guide to Fruits and Berries, Houghton Mifflin Publishing Co., 1996
Reich, Lee, Uncommon Fruits Worthy of Attention, Addison Wesley Publishing Co., 1991.