Watering trees in Arlington County

When trees get transplanted, they lose significant portions of their roots, and need time to get used to their new planting location. Below are some guidelines on what to do to establish new trees in Arlington County’s climate, and when you should think of watering older trees:

Watering new trees

During the growing season, newly planted landscape-size trees (usually 1-2 inches in diameter at the trunk, or about 8 ft high), prefer to get watered about 25 gallons every week. Of course when we have heavy rains, this is less necessary, but Arlington often has periods of relative drought, in the later summer, when watering becomes crucial for trees.

Unlike grass or other smaller plants, trees prefer slower watering, over a longer period of time. Here are some options for watering:

1. Use a watering bag (see image on the right), and follow the directions on the bag to make sure it drains properly. Remove the bags over the winter.
2. Lay a hose at the base of the tree, and let it flow at a low volume for about 30 minutes, before turning it off.
3. Use surface irrigation, around the base of the tree. Be careful to remove irrigation after the tree is established.

For a video on watering, check out Casey Trees’ watering video:

Watering older trees

Older trees may have established roots, and good access to water, but in cases of extreme drought, they can really benefit from extra water. Here are some options that work:

1. Lay a hose at the base of the tree, and water at low pressure for up to 1 hour.
2. Combine watering bags around the trunk of the tree, and fill these with water. Be sure to remove these after the dry season, as they can introduce decay in the trunk, if left on.

When do I water?

It is generally recommended that if less than 1 inch of rain has been recorded locally in a whole week, to water your trees. You can use the National Weather Service website to track precipitation:

http://w1.weather.gov/data/obhistory/KDCA.html

Another great resource are the Casey Trees watering alerts, which are posted on their website every week: http://caseytrees.org/

More information

Arlington County standards on watering

Casey Trees watering page

Watering Drought-stressed Trees