Lessons from a winter that was tough on trees, shrubs

We lost a beautiful 25-year-old Japanese maple near our pond last winter, and other Port area gardeners did as well. A survey of members by the Wisconsin Hardy Plant Society confirms winter tree and shrub loss in many parts of our state and provides ideas for better future selections.

We’ve already replaced the cut-leaf Japanese maple we lost with the same kind of tree. This may be foolish, but I think it will remain so small while I’m the chief gardener here that we can easily protect it. The loss of ash trees and seedlings in the utility right of way on the north side of our house allowed the winter wind to swirl into the yard for the first time. The cut-leaf Japanese maple was the most vulnerable tree on the WI Hardy Plant Society’s survey, and even wrapped specimens died, including trees at arboretums.

Our old ‘Bloodgood’ red-leafed Japanese maple, which is in a very sheltered spot, made it through the winter, although others around the state didn’t fare as well. A more recent introduction, ‘Emperor 1,’ did much better. It has richer leaf color than ‘Bloodgood,’ and with better cold hardiness and more compact size, it is probably a superior plant for Wisconsin.

Other Japanese maples fared much better, possibly because they need more shade and were better protected from the wind. Our full moon maple (Acer shirasawanum) had no damage, and that was true around the state. Vine leaf Japanese maples (Acer cissifolium) also did well, although hedge maples (Acer campestre) like ‘Carnival’ and ‘Pacific Sunset,’ which are grown for their colorful leaves, died from severe bark damage.

There were also statewide reports of damage on holly and wind burn on evergreens, especially boxwood. I think everyone has seen the sad state of most of our local boxwood, which were killed back to the snow line in many yards.

If we hadn’t wanted a specific look at our pond, I might have tried an ornamental elderberry (Sambucus) as a replacement for our cut-leaf Japanese maple. These plants are hardy to zone 4 and usually trimmed to grow as a rounded shrub. ‘Black Lace’ (Sambucus nigra), with almost black cut-leaf foliage, is the best known ornamental elderberry. It grows 6 to 8 feet tall and almost as wide and has 8 to 10-inch-wide pink flowers that produce berries for wildlife in the autumn. It needs a mostly sunny location, and in our area would appreciate acidifying soil amendments.

‘Golden Towers’ (Sambucus racemosa) is a narrow, upright plant that grows to about 10 feet tall but only 3 to 4 feet wide. It has chartreuse leaves and produces lemon scented flowers. Red berries for wildlife appear in the autumn. The seeds within the red berries, however, are poisonous.

Protective boxes for small trees and shrubs got excellent reviews in the WI Hardy Plant Society survey. They are made with 3/8-inch Thermax aluminum-covered sheet insulation. The are put together with aluminum tape rated for cold weather use. We’re going to try this on our new maple this coming winter. Plants covered with Thermax boxes survived, where frost blanket wrapped shrubs did not.