If you plan to grow a fast growing tree in your yard, the Thuja Green Giant is a good choice. The fact is, the Thuja Giant Tree is the fastest growing evergreen tree, making it a favorite of many homeowners. This evergreen can even grow 3 to 5 feet per year – pretty darn fast! Another good reason why this type of Evergreen Trees is very popular is because of its easy maintenance. The tree is very tolerant to drought, resistant to plant diseases and pests, and can easily adapt to any soil condition. Also, the tree could be planted anytime of the year. This evergreen tree grows best in zones 5 to 9. If planted in row, it can reach a mature height of 20 feet and a mature width of 5 feet (or more). If planted alone, the tree can grow up to 40 feet (or more) and can reach a mature width of 10 to 15 feet (or more).