Paulownia, known botanically as Paulownia tomentosa and more commonly as kiri, is a hardwood tree grown largely for its timber. This desirable species competes in the marketplace with black walnut in Japan and other regions, according to the University of Kentucky. An unusual and regimented pruning technique, known as the one-step method, creates the tall, large, straight logs of uniform size that are most desirable for paulownia timber sales.
Cut down three-year-old seedlings to just 1 inch or so above the level of the soil, an area called the bole, to encourage the development of multiple new trunks that are uniform in size. Use either secateurs or larger gauge loppers as needed to make a clean, crisp cuts on the seedling trunks. Place the cuts on the bias with the slope, facing the southern exposure.
Thin the new sprouts emerging from the stump once they reach 6 inches in height. Cut them back down to the bole just above the soil, leaving just the single most robust and largest diameter sprout in place, untouched. If deciding between two strong sprouts, prune away the one closest to the center of the stump.
Pluck or cut away the buds that form at the joints of the leaf branches and on the bole stump at least twice during the first year after re-sprouting, while they are still green and flexible. Allow several healthy buds to remain at the top of the seedling sprout to form the canopy of the tree.
Remove buds by pruning roughly once or twice a year to control the size of the tree canopy and the number of trunks that develop on the stump. As the trees age, use a ladder, lift or pole saw to prune the top branches in the canopy.