|Is the American Arborvitae different from the Giant Western Arborvitae? I'm more interested in the Giant because of its very fast growth rate and pyramidal shape. Is another name for the Giant Western Arborvitae the Green Giant Cypress? Also, will the Giant Western Arborvitae perform well in San Jose, CA? Thank you.|
|The plants in question are very similar; both are members of the same genus, just different species. Thuja occidentalis is the American arborvitae; Thuja plicata is the western red cedar. The Giant Western Arborvitae is classified as Thuja plicata; the Green Giant Cypress is a hybrid between Thuja plicata and Thuja standishii (a Japanese species). It is less cold-tolerant than Thuja occidentalis, but that shouldn't be a problem in your mild winter gardening region. Hope this information clarifies rather than confuses things!
Green Giant can grow 3-5' a year, ultimately reaching 30-50' tall and 10-20' wide. If you're looking for the fastest growing plant, Green Giant is the right choice.
Best wishes with your landscape!