The water needs of trees and shrubs are quite often overlooked. Young, newly-planted trees are particularly vulnerable. For the first two summers after planting, any tree or shrub can suffer, especially conifers. During dry spells of more than one week, a close watch should be kept for signs of drought.
Plants showing signs of shortage should get a good watering – about 20 litres per plant, every ten days or so. Apart from obvious wilting, the danger signs are a listless appearance and dullness of leaf colour, especially with conifers. Even big established trees can come under moisture stress and might need to be watered, especially if they have had any root disturbance in recent years.
Root disturbance such as excavation, or a change in ground water level caused by building or roadworks, may result in small-sized leaves, sparsely held and even dead twigs. New growth sometimes appears on the main branches as the tree adapts by dying back from the top. A large shrub or small tree can be watered effectively by allowing a slight trickle of water from a hose to percolate down into the root zone over a period of a day or more. Move its position to deliver a very large quantity of water without waste. For a tree with a wide root area, a sprinkler could be used.