Despite our cool spring, we are approaching the end of spring tree planting season. Planting a tree is a shock to its system, so it’s best to ease it in to its new home. Planting early in the spring before its leaves are out works well. This refers to deciduous trees, but planting time for evergreens is similar. Tree roots start to grow before the leaves appear, while the soil is still moist. When the leaves expand and the tree needs water, there is plenty available. If you were to plant a tree into dry soil, with its leaves expanded, it would have a lower chance of survival. In either case, watering is essential to newly planted trees. The SDOT Urban Forestry division has planted hundreds of street trees throughout Seattle this spring and is currently planning for summer watering.
As the weather warms up (soon, we hope), it’s easy to forget about watering your new trees until it’s too late. A tree watering bag is a great reminder and watering tool. It’s a bag that holds 20 gallons of water and zips around the tree trunk. It has small holes that let the water drip out slowly over about four hours. This encourages deep root development, instead of shallow surface roots. Irrigation systems often provide frequent, shallow water, which is great for turf, but not sufficient for young trees.
Here are some more resources for tree planting and watering information: