Ask a Consulting Arborist Q&A: Tree Care Tips (Pruning, Water, and More)

Q: What are the watering requirements of a Douglas fir tree?

Wednesday, January 20, 2016  

Q:  What are the water requirements of a Douglas fir tree of about 10 feet? Or better yet, what are the requirements by height and month?  There surely must be data to answer such a question. Thank you for your trouble.

A: There are several keys to watering trees:

  1. Do not allow the lower trunk to get wet.
    1. This allows pathogens to enter the bark and attack the tree.
  2. Slow water added over time is best.
    1. Soaker hoses work well.
  3. Water to a depth of 18 inches.
    1. Have the water begin 18 inches away from the trunk and extend 18 inches past the tip of the longest branch.
    2. You can buy soil staples to get the hose to go where you want it.
  4. Water from April through the end of October.
    1. Only water once a month.
    2. When the temperature rises above 80 degrees, water every two weeks.

Responder: Brian Gilles, RCA #418, Kirkland, WA