Thinking without the box

In 1997, when my garden took on the bone structure it has today, I chose common box (Buxus sempervirens) as an evergreen presence in several spots. 

Common box in the garden

This popular shrub is not a North American native; it comes from Southern Europe, western Asia and northern Africa. We planted a line of boxwood shrubs parallel to the side of the house to hide the bulkhead that leads to the basement. We placed one in the front yard where the driveway meets the sidewalk. We dotted three others around the property. I’ve enjoyed the boxwoods over the years, but now I’m seeing their downside.

    It’s nice to have evergreens to look at in the winter. With their small shiny leaves, the boxwoods stand out against the conifers around the periphery of the yard. If I were designing the garden today, though, I’d skip common box and use inkberry (Ilex glabra), instead. Inkberry is a native evergreen holly. Like box, it has small leaves and a dense growth habit that makes a good visual barrier. 

This inkberry is thriving in a back corner

A couple of years ago I planted two inkberry shrubs at the back corner of the yard after we took down an adelgid-infested hemlock. I’m impressed with how well they’re doing with benign neglect.

    This spring I’m reminded again that box without pesticide spraying is not pest-free. This year’s new leaves are shiny and unmarked. The older foliage, though, is stippled with tiny dots from insect activity. The bugs don’t kill the shrubs, and maybe no one notices the leaf damage but me.

Boxwood psyllids at work

 
    I’m willing to wash off chewing insects occasionally with a blast from the hose, but I’m not willing to resume spraying dormant oil to smother these leaf-eaters. I gave that up when I realized it was sure to kill insect bystanders as well as the target pests. The collateral damage became too high a price to pay.

I'm not willing to sacrifice bumblebees to keep boxwood foliage perfect

    So shall I accept the less-than-clean-looking box foliage as a cost of avoiding pesticides? My perspective on boxwood and other key nonnative players in the yard has begun to shift. I value native plants and insects more now, and I’ve come to accept the possibility that these large boxwoods, more than 20 years old, may not stay forever. It would take a long time for inkberry bushes to reach the same height and bulk, but the sooner they start, the sooner they’ll get there.

    It’s been interesting to observe how giving priority to native plants for native insects has gradually shifted my gardening choices and goals. I inched into this new commitment in 2011 thinking that I’d keep all my nonnative plants, especially trees and shrubs, and just add natives when they seemed right to replace something that dwindled or died. 

Native tickseed shoehorned in under day lilies

As the seasons pass, I find I’m increasingly populating the garden with native plants.