There are five main systems of planting trees: 1. Rectangular system - trees are planted in straight rows at equal distances. Used for grapes. 2. Square system - trees are planted at the corners of squares so that intercultivation can be done easily in both directions. Plant and row distances are equal. 3. Diagonal/quincunx system - like the square system but with an additional tree planted in the center of each square, allowing for double the number of plants but unequal spacing. The central tree may be shorter-lived.