Tree of heaven grows rapidly and forms dense thickets of suckering shoots from an aggressive root system. It produces large amounts of seed that is wind spread. It out-competes native species for sunlight and space, and produces a toxin in its bark and leaves that accumulates in the soil to prevent other plant species establishing near it.

Hand pull seedlings and small plants, and dispose of them at a refuse transfer station. Larger trees can be cut down and stumps treated with a suitable herbicide to stop them resprouting. Check out www.weedbusters.org.nz for more information on control methods.

Native titoki (Alectryon excelsus) or rewarewa (Knightia excelsa) can be an attractive replacement. For non-native alternatives, try weeping silver pear (Pyrus salicifolia ‘Pendula’) or ornamental crab apples (Malus floribunda). Your local garden centre will be able to advise on suitable non-weedy species for your local growing conditions.