Normally hedge is a line of closely spaced shrubs and sometimes trees. We recommend you choose "Shrub" or "tree" as you plant species. It's also common to have multiple type of plants in one zones. Usually, it's recommended to use the plant that needs most of waters. For example, if you have shrub, trees and flowers in one zone, it's better to use "flower". This is because tree can survive with more water, but your flower could die without enough water. One exception is Xeriscape, which could die with more than enough water.