It doesn't need any encouragement, it will grow fast enough without you helping it. I don't recommend leyland cypress (because that is what you have bought, albeit in a yellow cultivar) as hedging plant, because if it isn't maintained it becomes a problem. If you do miss a pruning, you may not be able to cut it back to the size you want, because if you cut it back beyond the living fronds, it doesn't reshoot, and becomes unsightly. You can't put the trimmings on your compost heap. The ground around it becomes bare earth as nothing will grow near it. And it smells horrible too. At least the yellow one isn't quite as rampant as the green one...