Morus alba, the white mulberry, has been in the United States since the early 17th century, brought here to establish a silk industry that never materialized. Originally it was native to China, where it has been the main food source for the silkworm for almost 5,000 years. The white mulberry is now naturalized in much of the United States, where it is considered an invasive species in many states. It is so restricted because the species is prolific at hybridizing and out-competing with the native species Morus rubra which has value to the local ecology.
Though attractive in the landscape, Morus alba should only be planted if and only if it is not illegal to do so and if you plant one of the numerous sterile cultivars available in the nursery trade. Otherwise, if you have your heart set on some delicious mulberries, choose the native red mulberry (Morus rubra) or Texas mulberry (Morus microphylla).
|Common Name||White mulberry|
|Botanical Name||Morus alba|
|Plant Type||Deciduous tree|
|Mature Size||30-60 ft. tall, 20-40 ft. wide|
|Sun Exposure||Full sun to part shade|
|Soil Type||Rich, moist, well-drained soil|
|Bloom Time||Early spring|
|Flower Color||Yellowish green|
|Hardiness Zones||4 to 8 (USDA)|
White Mulberry Tree Care
White mulberry trees are easy to care for, to the point that they are too hardy and prolific, leading to their ability to thrive in almost any condition within its hardiness zone. If you have a straight species—Morus alba—to care for, the majority of care involved will be the maintenance involved in keeping the tree's weediness in check and cleaning the mess caused by its abundant berries. These berries can cause a disastrous mess under the tree, especially by hardscaping, structures, or vehicles. When birds eat, the fruit can also cause a mess when left as droppings.
If a white mulberry is located in your garden, pruning and removing new seedlings will also be part of your yearly lift. White mulberry does not rely on other living things to pollinate it. The genus has a mechanism that catapults its pollen away from its catkins at half the speed of sound, making it the fastest plant alive and insanely weedy.
The straight species of white mulberry is invasive. Even if it is legal to plant this tree where you live, it is unlikely that you would want to because of how it affects its ecosystem and the established landscape. Consider one of its non-invasive cultivars to plant instead.
The species performs best if placed in an area which receives an ample amount of full sun but it is incredibly adaptable and will manage in part sun to partial shade as well. Its ability to seemingly spread endlessly will have the tree pop up and do well in almost all conditions, but this should not be considered license to place cultivars of the species in anything less than full sun.
It is not often you will be able to plant or see a tree grow in any soil condition. You can do exactly that with white mulberry trees. In urban areas, they are often known for growing in empty lots riddled with construction debris. The only condition it will not survive in is soil that is saturated consistently. When planting a cultivar of course you will not be attempting to allow your tree to eke out survival, your goal will be giving it the best conditions for it to thrive and in that case, providing it with rich loamy soil, that is well-draining with a neutral pH.
White mulberry trees do not need any supplemental watering once established and at that point, they become very well suited to areas that experience drought conditions regularly. Until then though it is important to proceed as you normally would with most trees and provide your newly planted mulberry with enough water to allow it to establish a good robust root system. This is easily achieved by watering your tree weekly during its growing season at a rate of 10 gallons per inch of trunk diameter measured by a caliper at chest height. Doing this for the first two years will ensure that your tree is nice and healthy and able to cope with whatever stresses that are thrown at it.
Temperature and Humidity
The hardiness of the white mulberry is not an issue. It stands up well to droughts and cold weather in its habitable zone, USDA 4 through 8, quite well, but the main weather concern regarding the species comes from its weak wood. While it stands up to the weather quite well, its wood just does not have the strength to compete with strong winds or heavy build-ups of ice or snow on weak branches.
You should not add supplemental fertilizer to a white mulberry tree as it grows vigorously on its own in even the most adverse conditions. Adding fertilizer will only speed the growth of this fast-growing tree, weakening the wood further possibly causing tree damage during storms and poor winter weather. If you consider using supplemental fertilizer, you should test your soil before adding amendments to see what micronutrients are lacking and supply the fertilizer with the right NPK formulation.
Types of White Mulberry Trees
As mentioned above, you should not plant the straight species of Morus alba. If you intend to plant a white mulberry, be sure to check with your local officials to see if planting is prohibited. Regardless of the legality, consider planting one of these fantastic cultivars that are sterile and bear no fruit; this keeps the tree from becoming weedy and also aids in keeping the messiness that makes the white mulberry notorious. Or perhaps check out another species of mulberry tree native to your area.
- Morus alba ‘Chaparral’ is a fruitless dwarf cultivar with a maximum height of 8 feet and severely weeping foliage.
- Morus alba ‘Stribling’ is a fruitless variety with broad irregular leaves with medium green foliage.
The chore of pruning your white mulberry will be done mainly for maintaining the tree in order to ensure it does not break under the stresses of winter weather or high winds. This should be done by looking for weak, intersecting branches with deep crotches, damaged or dying branches, and wood that is growing inwards towards the leader. This task should be done during the winter to avoid unsightly bleeding that occurs when the genus is pruned which can in turn allow some diseases to infect the tree.
Your second task when pruning and trimming, when dealing with the straight species, is removal of any newly sprouted seedlings or saplings in the vicinity. Carefully remove from the root all plant material and dispose of the waste properly according to local ordinances.
As with the planting, the propagation of white mulberry is not advised. It is considered invasive and a noxious weed in many states and many local governments have ordinances against growing the species. Before considering propagation, check with your local extension office to see the legality of its propagation.
Common Pests and Plant Diseases
Morus alba does not suffer many issues from insects or diseases. It will occasionally become infected by bacterial leaf scorch, root rot, or cankers, but none of these will be a life-threatening risk.
The insects that might plague your tree are often flies which might have to do the fruit mess or whitefly infestations. Borers may be an issue in warmer climates but will not pose a serious risk. Ultimately neither the insects nor the diseases should be the reason for chemical intervention, and time should do the trick.