Willow, Salix alba, trees are known for their oversize trunk, broad and drooping canopy, and vigorous growth make these stand-out trees in the landscape. These dramatic trees will grow to be around 30-40 feet high and 35 feet wide. They grow best in full sun or partial shade (needs at least 4 hours of direct sunlight every day). They thrive in a wide range of soil conditions from well-drained to clay soils. You typically see willow trees near water, that's because they grow best when near water, but they do have some drought tolerance.