What’s Wrong with the Boxwoods?

Have your boxwoods been struggling this year? Ours too. Here’s what our Horticulturist, Caroline, has to say about the situation—and what we’re planning to do about it.

In the past decade, we've seen an increase in a fungal disease called boxwood blight. Initial symptoms include light or dark brown leaf spots, often with dark borders. Infected plant leaves turn brown or yellow and quickly drop from the plant. The fungus also forms black diamond-shaped lesions on the stem tissue. Again, this disease has no cure, but cutting back the infected tissue, heavy mulching to keep the soil spores down and adding fungicides regularly throughout the grow season can keep the symptoms at bay.

The second pressure this year is the Box tree moth, an invasive pest from Asia whose larvae feed first on the leaves of the boxwood and then, when that’s gone, on the bark, ultimately girdling the plant. You can recognize this moth by the webbing that the caterpillars create as they mature, which you’ll see if you spread the branches and look into the interior of the shrub.

The third pressure is the cold snapping of our winters. This past fall, we went from extremely hot and dry to really cold and wet almost overnight. This left the plants little to no time to harden off, which is the process by which their leaves adjust their levels of photosynthesis to protect them from the cold. This cold snap affected most of our conifer species and has exacerbated symptoms from the other two pressures.

While these pressures individually are not enough necessitate removing your boxwoods, all of these pressures together can make your favorite low-maintenance plant not-so-low maintenance anymore. If you're set on keeping your boxwoods, you can always cut 30 percent of the plant's foliage back to help it regrow while mitigating the pressures it’s facing.

If we’re being totally honest, boxwoods don’t provide much (if anything) ecologically, so here at the CGC, we’ll be phasing ours out. Watch this space! And if you’re looking for a native alternative for your own struggling boxwoods, native bayberry, junipers, chokeberry and American holly would all be good options.