Arborvitaes are a slow growing plant variety (generally less than 12 inches per year of new growth) .The Arborvitaes are hybrids so they are propagated by cuttings as they will not come back true from seed. One of the Arborvitae, the Green Giant, the Western Redcedar Tree, or botanically, the Thuja Plicata, is the favorite. Here is why:
The hardiness zone the Green Giant Arborvita tolerates is from zone 5 to zone 8. That’s where extreme cold temperatures get down to a temperate level of about 15 or 20 degrees in the winter (Zone 8), but also as low as a frigid level of 15 or 20 degrees below zero (zone 5).
Green Giants are evergreens, being cedars. Their rapid growth rates can in ideal conditions reach 3 feet per year. Site requirements for the Green Giant Arborvita are sun to partial shade, moist well drained soil preferred (but still does well in clay), and protection from wind, at lest when young.
The Green Giant is a beautiful tree. It has an aesthetically fine form. It’s conical, being narrow to broadly pyramidal, reaching from 50 feet to 80 feet in height in southeastern Pennsylvania. The width at the base of the cone is usually about 15 feet to 20 feet. The leaves are rich green making graceful foliage.
Green Giants make a superb privacy screen. They keep their foliage color year ’round, great for brightening bleak gray winter days with snow on the ground. The cinnamon bright red bark when young turn rich russet brown with time crating a strong contrast with the needle leaves.
Green Giants’ flowers, their fruit are pretty little light brown half-inch female cones. (Green Giants are females, so its okay to call the cones pretty.)
The Green Giant is also a wonderful shade tree, casting a dark, dense shade. The wood is strong too, once the tree is beyond its youth.
This is an Arborvita that should outlive even your grandchildren. There are Green Giants out west documented to be over 300 years old. Just don’t plant these too close to the ocean, or roads in areas where there’s a lot of salt used for snow removal. If you get over 100 inches of snowfall and more per year, no roadside Arborvita planting where salt is used. The greatest soldier of ancient Greece in the Trojan war had his one little weak spot, what proved to be a fatal flaw, and the ‘Achilles Heel’ for Green Giant Arborvitae is hypersensitivity to salt.