Watering Newly Planted Trees
A watering bag holding 20 gallons of water slowly applies water to the root zone of a tree.
Watering newly planted trees for the first two summers helps trees re-grow the roots they lost during transplanting. It is the single most important thing you can do to ensure their survival. A good starting point for determining how much water to use is 5 gallons-per-inch of tree trunk diameter per week. However, depending on the weather and the soil-type, more or less frequent watering may be necessary.
The only sure way to know if your tree needs water is to feel the soil. Avoid short, frequent watering as it promotes shallow rooting. Instead, water slow and deep. Soaker hoses or watering bags are effective tools for watering, Or you can use a slowly trickling hose which will apply approximately 5 gallons of water over a period of an hour. Another alternative is to drill several small holes through the bottom of a five gallon bucket and set it over the root ball of a tree. Filled with water, it will slowly drain, providing water right where it is needed.
Try to water in the evening or early morning to minimize evaporation. The extensive root systems in older trees enable them to better tolerate dry conditions, but they may benefit from occasional watering in a drought situation.
Over-watering is as bad for newly planted trees as under-watering, because a tree is unable to access the oxygen it needs to survive, so use your judgment.
Weeding and mulching under your trees with wood chips, compost, or beauty bark is an excellent way to conserve soil moisture and promote healthy trees. Apply mulch to a depth of 2 - 3 inches. Deep mulch covering the bark invites insect and disease attack, so make sure to lay the mulch at least 4” away from the trunk. Fertilizing newly planted trees is not recommended.
Both watering and mulching are two easy and inexpensive things you can do to protect the trees in your neighborhood. Ten gallons of water per week costs only 3 cents at peak summer rates.
As part of the Bridging the Gap program, SDOT will help provide citizens 100s of trees city-wide. You can do your part to help continue Seattle’s forest legacy by caring for your trees.
More information about tree care can be found in A City Among the Trees, an Urban Forestry Resource Guide, available at your local library or the City Arborist Office for $15. Contact SDOT Urban Forestry at 684-8733 for details.
Watering to Establish Your New Plants