Willow trees have extensive and often invasive root systems, making them excellent for stabilising soil near water and on hillsides, but bad for septic systems and underground water pipes. Because the roots spread wide and deep, digging them out can be difficult if they are over a few feet tall and a few years old. Dig out willows in late fall or early spring while they are dormant if you want to transplant them to another part of your landscape.
Soak the soil around the willow for several days before digging. Water all the way out to the drip line of the widest branches to soften the ground and help ease transplant shock if you want to save the tree.
Estimate the width of the willow. If it's 4 feet tall, set the point of the shovel 2 feet from the trunk. Dig in a circle around the tree, angling the shovel at 45 degrees down toward the trunk. You won't be able to avoid cutting some of the side roots, but many of them will regenerate after transplanting. Dig firmly and cut through them cleanly.
Once you've dug in a circle to a depth of 2 feet around a 4-foot willow, go around again, digging a little deeper and prying up. If the tap root resists firmly, dig down another 6 inches and try prying again. If it still resists, reach into the hole with a pair of long lopping shears and cut the tap root as far down as you can reach.
Lift the willow out of the hole from beneath the root ball, but don't pull up on the trunk. Pry up the roots with the shovel and tip it out of the hole onto its side. Get a partner to help you lift it into a wheelbarrow. Set the willow into the wheelbarrow and transport it quickly for transplanting.
Plant willows near water where they can get plenty of sun. Many willows can grow to a height and spread of more than 75 feet in their short lives, and they need a lot of space.
Don't plant willows near septic systems or water pipes.