Are you noticing some evergreens that have come out of the winter looking worse for the wear? The boxwoods, hollies and southern magnolias are showing a good bit of burn.
You can normally expect some dieback on roses, but it’s extreme this year on some varieties. Marginally hardy plants, like crape myrtles, have taken a hit. We haven’t seen a winter like the one we just had in, well, ever. Not exactly.
The cold came on hard and sudden in December, without the benefit of an insulating snow cover. Temperatures stayed seasonally cold, except when they didn’t, and then repeated late frosts turned magnolia blossoms into mush. Certain varieties of tree fruit won’t bear this year because those late frosts did the flowers in. Or temperatures were too low for the pollinators to work at the time of bloom. You know the story.
Folks are often eager to help plants to recover, and it’s important to understand the source of the winter injury before acting. Winter injury can come from:
Moisture loss, which is a risk especially to evergreens
Windborne ice-melting products — kicked up by traffic and wind — contacting evergreen foliage and drying it out
Runoff from ice-melting products, which — through osmosis — cause water to move in the wrong direction across root membranes, drying out the plant
Freezing temperatures before a plant is hardened-off for the winter, or after it has broken dormancy
On evergreens that dried out or “burned,” leaves may drop and/or stay ugly for a time. I’ve watched certain pine trees — year after year — start spring with brown needles on their windward side from traffic spray and ice-melter. Not ideal, but they seem to recover. If you suspect that runoff from ice-melter is a factor, flushing that salt out of the root zone is worth a try. Yes, extra water.
Whatever you do, please don’t give winter-damaged plants extra fertilizer. This will push growth that the plant may not be prepared to support, causing unnecessary stress and damage to the plant. Consider slow-release fertilizer for any application on landscape plants, and keep it on the light side. Tender succulent growth promoted by heavy fertilization is attractive to fungus diseases and insect pests. Go easy.
Prune out dead or damaged stems, always to the branch union or the ground — no stubs, please. If you are working with fruit trees, or suspect an infectious disease like fire blight, disinfect your pruners with rubbing alcohol between cuts and between trees. We are at the stage of spring where the extent of winter damage is probably clear, and spring fungal diseases are active.
For more on winter injury, check out this online article: ag.purdue.edu/hla/Extension/nle/Articles/TheRevealingEffectsofWinteronTresandShurbs.pdf.
If you’ll be planting new landscape plants this spring, think about prevention. Choose plants that are fully hardy in our United States Department of Agriculture 6a Hardiness Zone. Avoid planting evergreens downwind from traffic spray. Pay attention to where runoff from ice-melter will go, and — if you must plant there — choose plants that are salt-tolerant. We can help with selection ideas for plants that can thrive under your growing conditions, including squirrely winters.
Kris Medic is Purdue Extension Bartholomew County’s educator for agriculture, natural resources and community development. She can be reached at 812-379-1665 or [email protected].
