Size Potential

• In its natural setting, a Douglas fir can reach heights of 300 feet or more. Many specimens are between 100 and 200 feet tall. The State of Washington Department of Natural Resources noted that living trees have been documented at about 16 feet in diameter and at heights of around 326 feet. As a landscape tree in backyards and residential areas, a Douglas fir typically achieves 40 to 60 feet in height with a spread of between 12 and 20 feet.
  
  

Tree Longevity

• It is not uncommon for a Douglas fir to live for 600 to 800 years. Some trees are documented at over 1000 years of age, with some of those living between 1300 and 1400 years. Tree height and dimensions, however, are not good indicators of age. Some young trees grow tall in just 20 years or so, while old trees may live for centuries but not attain more than 100 feet in height.
  
  

Fire and Decay Resistance

• One reason for the longevity of a Douglas fir is its thick bark, which helps protect the tree from fire as well as from attack by insects and fungus that may cause the tree to rot. Douglas fir bark grows on the outside of the cambium layer, pushing older bark out. The tree keeps growing bark for years, much longer than other trees, and ends up with a thick layer. Douglas fir bark can be as thick as 14 inches. Charcoal stains on the outside of many Douglas firs indicate brushes with fire.
  
  

Soil Conditions

• Douglas firs tolerate a wide variety of soil conditions as long as they do not harbor standing water. Trees can grow in clay soils, sandy loams, silt, acidic conditions and loam. These trees root well in moist conditions as well as in well-drained soils.