Weeping willows are fast-growing trees, adding up to 10 feet per year when young, but their average lifespan is a relatively short 30 years. Plant your weeping willow in the fall to give the root system time to establish itself before the warmer weather. These trees also should not be planted near sewer drains, septic systems, or water lines: Their root systems are aggressive—sometimes stretching wider than the tree is tall. Not only do they seek out the nearest and most abundant source of water, but they are attracted to the nutrients in the soil around a septic system, as well as the oxygen in the drainage lines.
Light
Full sun, or partial shade in the southern end of its hardiness range, is best for this tree. It needs at least four hours of direct, unfiltered sunlight each day.
Soil
This tree is tolerant of a wide variety of well-draining soils and soil pH (4.5-8.0). Although it prefers moist, slightly acidic soil, it grows well in alkaline, loamy, rich, sandy, and clay soils. If your soil is too alkaline, add some organic matter to lower the pH.
Water
Willows like standing water. Their long, far-reaching root systems can be helpful in clearing up puddle- and flood-prone areas of a landscape. They also like to grow near ponds, streams, and lakes.
Temperature and Humidity
Weeping willows have some drought tolerance and can handle the winter cold. The tree can also tolerate summer desert heat as long as greenery and water are not too far away.
Fertilizer
A mature weeping willow does not require fertilizer if it is planted in rich soil and its leaves are a healthy green or nearby lawns are fertilized regularly. However, you can supply fertilizer to support lush growth. Perform a soil test before adding any soil amendments, with the exception of slow release organic fertilizers, such as mulch.
Types of Weeping Willow
There are several excellent varieties of weeping willow, including:
Golden weeping willow (S. alba ‘Tristis’) has green leaves that turn golden in fall, adding autumn interest.Wisconsin weeping willow (Salix x pendulina) is a hybrid that grows quickly to 30- to 40-feet tall and wide.Thurlow weeping willow (Salix x pendulina ‘Elegantissima’) is a pyramidal weeping willow with longer, pendulous branches.
Pruning
While the tree is young, prune it so that there is only one central leader. It should also be trained to have wide branch crotches to help prevent breakage, as the tree is somewhat brittle and can be susceptible to wind damage. It is a good idea to prune a weeping willow in February or March, snipping back all its branches. This will trigger the sprouting of new branches and will give the tree more vigor.
Propagating Weeping Willows
Propagation of Salix babylonica is done through hardwood cuttings.
Common Pests & Plant Diseases
Weeping willows can be struck by several pests, including the gypsy moth, aphids, and borers. These insects are difficult to control—especially on large trees—but targeted spraying with pesticide can help. Young weeping willows are also tempting to deer, elk, and rabbits; place a collar around young trees to protect them from wildlife. This tree may be affected by several ailments and diseases, including willow scab, crown gall, willow blight, fungi, cankers, leaf spot, tar spot, powdery mildew, rust, and root rot. Symptoms include branch or twig dieback and defoliation, but in some cases, the disease can kill the tree. To minimize problems, provide adequate water to keep the tree healthy, since healthy trees are better able to fend off disease. Rake up and remove leaf litter promptly, to control the spreading of disease. If these methods do not work, fungicides might.
