I planted 5 THUJA conifers about 2 years ago as a border at the side of my house. They have grown quite tall but don’t seem to be growing widthways much at all. Somebody told me if I cut the tops off them they would spread out widthways. Do you think that is a good idea? Or would you have any other suggestions? It said on the label that they would grow to 15 metres tall and 4 metres across. They are now about 2 metres tall & 2 foot wide.