Rocky Mountain Douglas-fir

## Identification and landscape use Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca), also called interior or blue Douglas-fir, is an evergreen conifer native to the Rocky Mountains and interior western North America. It is distinct from the coastal variety and generally has bluer foliage and slower growth. Allow substantial space for its mature canopy. [UF/IFAS Extension](https://ask.ifas.ufl.edu/publication/ST528) describes the variety and notes that cold hardiness varies with seed source. ## Growing conditions Use a sunny location with suitable drainage and adequate soil moisture. Choose stock adapted to the site's climate and consult local guidance on irrigation and pests. UF/IFAS describes landscape trees approximately 40–60 feet tall; forest trees can grow much larger. ## Firewise source guidance The [Idaho BLM fire-resistance database](https://www.blm.gov/sites/default/files/documents/files/Fire%20Resistance%20of%20Plants%20Master%20Database.pdf) lists var. glauca at score 1, with a 100-by-20-foot example, full sun and medium water. The conifer table calls for pruning lower branches and clearing dead needles. This score applies to the named variety in the source; follow local defensible-space guidance and allow for tree age, site and maintenance.