One of the most characteristic of the differences is in the cones. Fir cones are some of the most attractive of all the conifers. They begin as small, blue to purple, berrylike structures on stems and mature into somewhat papery cones that have the unusual trait of sticking straight up on the branches, unlike the cones of other conifers, which hang down. Another attractive feature of firs is that there are several colors to choose from, ranging from dark green to gray to blue. One way you can be certain you have a fir is to look at the leaf scars on the branches.
Firs always leave a distinctive round scar or depression on the stem.
While all wild species of firs are tall trees reaching 50 to 200 feet at maturity, many dwarf forms are available, allowing the homeowner to choose plants that will remain as small trees or even shrubs that stay under 2 feet. As long as a particular fir species does well in your area, its dwarf form should perform well too. Firs flourish in well-drained, acid soils in cool, moist climates and as such, can be challenged when planted in the Midwest. Intolerant of air pollution and extremely hot, dry summers, firs will not do well as city trees. They require good moisture as young trees, but as they mature, they will require little if any additional water.