How to Grow and Care for Black Willow (Salix nigra)

Black Willow Catkins Along a Stream

Famartin / Wikimedia Commons / CC BY-SA 3.0

In This Article

The black willow is a fast-growing tree native to the United States that thrives in wet conditions. It looks lovely, but this tree can be problematic and thus should be fully understood before you decide to plant one. Its light, weak wood is known for breaking easily and suffering ice and wind damage, so placing it near structures or any street or pedestrian traffic is risky. The black willow's constant need for water makes it aggressively seek out sewer and water pipes, which can lead to very expensive damage, making it a bad choice to a place near a home. The "right tree, right place" mindset definitely comes into play when designing a landscape with the black willow. There are many other preferable wet site trees available.

Common Name  Black willow
Botanical Name Salix nigra
Family Name Salicaceae
 Plant Type Deciduous tree
 Mature Size  30-60 ft. tall, 40-60 ft. wide
 Sun Exposure Full sun, part shade
 Soil Type  Moist, well-drained soil, wet soil
 Soil pH  4.5 to 7.5
 Bloom Time  Early spring
 Flower Color  Gold
 Hardiness Zones  USDA 4a-9a
 Native Area  Eastern to Midwest North America

Black Willow Care

The most important care you can give a black willow is planning the right site to place the plant and deciding what form you'd like it to be. A black willow can be kept as a shrub by cutting it back to soil level every two to three years. The location you choose will affect care the most. Suppose you decide to plant your black willow in the wrong location. In that case, the amount of care you will need to perform on the tree will go up exponentially and so, potentially, will the cost of the care and repairs involved in maintaining your tree and the property around it. Tree experts developed the philosophy of "right tree, right place" for trees just like this one.

Light

While the black willow demands cool wet conditions it does not tolerate the shade of any sort. This is a tree that only thrives if you give it a full six hours of direct sunlight a day, anything less will decrease its vitality.

Soil

The black willow loves moist, well-drained soil but is very tolerant to different soil conditions, especially soil pH. The only issue that will arise is when your soil gets too dry or does not have good moisture retention. Dry conditions can be supplemented by regular irrigation. Avoid planting the tree in fully saturated areas, particularly if it's an area where it would be hazardous to have the tree fall over.

Tip

Black willows can be especially beneficial when planted in wetlands and near ponds, particularly if the ponds are overrun with algae. Ponds with high algae content are saturated with nitrogen fertilizers. Planting willows helps sequester some of the fertilizer and clean up the wetlands.

Water

Irrigation is the most important component in keeping your black willow happy. The species needs to have constantly moist to wet conditions and can even deal with flooded conditions for an extended length of time without suffering any ill effects. Obviously, the best solution is to plant in a spot that is constantly wet contains a good amount of moisture. Planting in an area that is wet regularly will help you avoid the need to add supplemental watering.

Temperature and Humidity

Salix nigra does not perform well in hot dry temperatures and these conditions should be avoided to ensure the health and success of your tree. Your black willow will be much happier in areas that are cooler and damp, like coastal areas. While some locations in its habitable range do get humid the unifying factor is the moisture. As long as its environment is on the temperate side and damp it will thrive, but going out of its USDA hardiness range of 4-9 is not recommended.

Fertilizer

The black willow is not a tree you will need to fertilize regularly. The tree is already extraordinarily fast-growing, and adding fertilizer to the soil will increase the growth rate, further weakening wood that is already prone to wind breakage.

Types of Black Willow

There are not many cultivars of black willow available in the nursery trade. The lack of cultivars available is mostly because other species are more suitable for use in ornamental horticulture. One exception is the cultivar Salix nigra 'Webb', which is strikingly different from the straight species. 'Webb' has a vase-like form and is smaller in stature than its parent species.

Pruning

Pruning should be done regularly to establish form, help establish structure, ensure a single leader's presence, and eliminate dead, damaged, and decaying limbs. These chores should be on your regular maintenance list to avoid larger expenses that can occur from property damage in the future if limb and branch breakage occurs during ice or wind storms. If your tree becomes too large to safely cut from the ground, be sure to bring in the help of a certified arborist.

Common Pests and Plant Diseases

Your black willow is bothered by numerous pests and diseases that are luckily determined to be more of a nuisance than anything. The forest tent caterpillar, cottonwood leaf beetle, willow sawfly, and a few different species of borers are most often seen. The wildlife value of the black willow makes the use of pesticides a concern, especially as it is the host plant to numerous butterfly and moth species such as the mourning cloak, red-spotted purple, viceroy, and tiger swallowtail. It is recommended pesticides be used as only a last resort, and other integrated pest management approaches are explored before they are used.