The lone voice of horticultural reason
“Arborvitae grow in shade”
A vexing myth because, taken at word value, it’s true. But this particular truth is not what you want to hear.
That arborvitae grow in shade is just the nursery industry stating, correctly, that arborvitae don’t die in shade. But that’s about it. When grown in anything less than five hours of direct sunlight, arborvitae (Thuja occidentalis) don’t grow quickly, they don’t stay tight, and they sure as heck don’t make any type of formal, clipped hedge.
Too often, that’s what homeowners expect. Want a nice, evergreen hedge in a shady spot? Landscape designers will tell you to grow arborvitae. Helpful staff at the nursery will say the same thing. They’re not wrong, but you’ll be disappointed. Any of most popular arborvitae varieties, ‘Techny,’ ‘Rushmore,’ ‘Pyramidalis,’ or ‘Holmstrup’ will start out tight and full (they’ve been field-grown in full sun), but over the next three to five years they’ll get loose and lanky.
Is there any recourse? You could try growing yews (Taxus spp.), an evergreen that will perform much better in part sun to shade, but you have that vexing winter burn problem. The trick is to water yews well in their youth, then erect a burlap shade wall six inches away from the shrub blocking it completely from winter sun. After four or five years of developing a good, hardy root system, well-maintained and fertilized yews will not burn in the winter, and one can dispense with the burlap. As is the case with all evergreens, watering yews in the fall straight up until ground freeze is also an essential task.
The Renegade Gardener