Q.two trunk japanese lilac
On a 2-trunk 3-year-old Japanese lilac tree, does it matter which one is cut to make a single trunk? I planted two mail order root Japanese lilac trees. Two years later one has a single trunk the other 2 trunks. Does it matter which trunk is pruned (equal diameter) and how close to ground?
I would wait until the tree is dormant to prune.
I would leave 1 to 2 inches of trunk. You may have sucker growth in the spring and would want to trim those away as soon as they grow.