Thin out the Japanese fantail willow by cutting individual branches back at the point of origin. Other methods are to cut the limb at the lateral branch or at the "Y" shape formed by the junction of two limbs. Cut the tallest and oldest limbs first. This method allows for air circulation and sunlight to reach the interior of the shrub.
Remove the oldest limbs down at the ground level if your Japanese fantail willow is overgrown and unwieldy. This helps control the size. If the bush requires a major overhaul, do this over a three year period in order to maintain the health of the shrub.
Shear the shrub to give it a more formal look. Cut the branches at a slant approximately 1/8- to 3/8-inch beyond a bud. You can do this at any place you desire on the length of the stem as long as the cut is made above a bud. This prevents the buds from drying out during the winter pruning.