Facts About How Long an Evergreen Grows

Seed to Adult

• One measure of when an evergreen has reached adult maturity is whether its cones produce living seeds that will grow and reproduce. For some varieties, this takes six years while others may take 20 to 50 years or more. The oldest-known evergreens are bristlecone pines growing in eastern California, with some trees more than 4,000 years old.

Needle Life

• The distinguishing characteristic of evergreens is the fact that they keep most of their leaves or needles, even in the winter and do not change color in the fall, remaining green year-round. However, this does not mean that all the green foliage continues to grow indefinitely. According to Colorado State University Extension, all evergreens drop their older leaves from the inner part of the branch in winter or new growth time in the spring, while leaving the younger ones in the mid-range and tip. Needle life ranges from two to 17 years in the different species of evergreen

How Old?

• The age of an evergreen tree tells you exactly how long it has been growing but calculating the age is difficult without injuring the tree and making it susceptible to insects and disease. Forestry specialists can determine an evergreen's age by taking a core sample and counting the growth rings. Environmental conditions such as temperature, water supply, natural disasters, insect infestations and disease affect the width of each ring.

Space

• When planting evergreens, plan enough space to allow for the roots and branches to spread out as they mature. Some varieties will grow extremely slowly. Planting in too small an area or places where buildings, walkways, driveways and roads will block root spread will stunt root growth. If the roots cannot expand sufficiently to support the top growth of the tree, it will stop growing, wither and die.