Gardener Job - The Orchards, GP, 0182

My lawn is artificial grass. On the sides I have planted trees (not sure about their name) they are yellow mixed with green color when they grow I wanted them to join together do that I can trim them and make my garden beautiful. I'm disappointed because they don't grow I'm not sure how long do they take to grow. I need service that they can be nurtured with fertilizer, manor or anything that xan grow them and become beautiful.