Q: We have two European hornbeams on either side of front stoop. We were told the tree would not change shape much or grow very high. However, after the first year it is growing much higher and starting to spread out. When is the best time to trim it?

A: An upright hornbeam tree is the wrong plant for your site. It grows 25 – 35 feet tall and 10 – 15 feet wide. Unless you can commit to regular pruning, I’d advise you take it out and plant a columnar evergreen like ‘Emerald Green’ arborvitae or weeping yaupon holly.