Hi, Last summer I let some lilac suckers grow at the bottom of a 3-trunk old lilac tree, which subsequently ended up getting blown down in strong winds. Now the suckers are about 3 1/2 feet high. Should I be cutting the stems back to encourage branching and bushier growth? If so, how much? What should I be doing to nurture it? Also, how many years before I might see the first blooms? The original trees had been here for many years and the trunks were about 4-5”diameter, with classic lilac scent, so I’m pretty sure it's a common lilac. Pictures attached. Thank you.