I have an inquiry with regards to my winter gem boxwoods located in the front of my house (front of my house is East facing, located in Etobicoke, and we get a good mix of direct sun and shade throughout the day). All the boxwoods have turned a nice healthy green in recent weeks, and I’ve given them a very light pruning. Unfortunately one of the boxwoods appears to have dried out and I tried trimming it back to eliminate as much of the dry/yellow leaves and stiff branches. Beyond that, I haven’t done much more, so I wanted to confirm what would be my best option at this stage? Is there anything I can do to attempt to revive it? Should I remove and replace it? Or should I remove it and reposition/space out the shrubs next to this one (without disturbing them and risk them dying) to fill the space out? Attached are some photos. I look forward to hearing back.
Thank-you for contacting Toronto Master Gardeners with your question.
Sadly, boxwoods have fallen prey to a number of pests and diseases in Ontario in recent years. Susceptible varieties continue to be sold in nurseries despite these well-known problems. As in your case, people often invest in numerous plants to form hedges and borders.
Having said that by way of warning, your situation looks more like winter damage than a disease/pest issue. The other plants appear to be healthy and in good condition. Most likely, the severe winter we just experienced is the culprit and that one plant was unable to survive the long, frosty winter. Because your hedge is right beside the walkway, salt damage is also a possibility. Your plants look to be fairly young and a young or newly planted shrub can quite easily succumb to either of these conditions. Since your plants are fairly small, you can remove the dead one and replace it with another of the same variety. Even a small plant should bulk up to fit into the space quite readily. Before purchasing and planting another specimen, however, double check on your spacing. The recommended spacing is 12 to 24 inches between plants (measured from trunk to trunk). You may be able to allow the existing boxwood neighbours to fill in the gap with a bit of judicious pruning.
In the event that your plant has died from one of the current scourges, either boxwood blight or boxwood leaf miner, it is very likely that the adjacent plants in your hedge will also fall victim. There are some treatments, but unfortunately many gardeners are finding that they need to pull up the boxwood and replace it with another type of shrub.
Here are a couple of comprehensive guides to boxwood diseases and treatments (keep in mind that some of the pesticides referred to in these American sources are not sold in Ontario).
The following link is to a general article on growing Winter Gem Boxwood: