This winter was hard on rhododendrons, but don’t be too quick to cut them back

  • A portion of a rhododendron bush is withered out in front of Brochu Nursery in Concord on Thursday.

  • Brochu Garden Center manager Rob Farquhar looks over a sickly Rhododendron bush out in front of their nursery on Thursday, May 2, 2019. Fraquhar feels like this particular plant can come back this spring. GEOFF FORESTER—Monitor staff

  • Brochu Garden Center Manager Rob Farquhar looks over a sickly rhododendron bush in front of the nursery Thursday. GEOFF FORESTER photos / Monitor staff

  • Brochu Garden Center Manager Rob Farquhar scrapes off the bark of a rhododendron bush to check its health. GEOFF FORESTER / Monitor staff

  • Brochu Garden Center Manager Rob Farquhar looks over a rhododendron bush at the nursery Thursday. GEOFF FORESTER / Monitor staff

  • Brochu Garden Center manager Rob Farquhar looks over a basically healthy Rhododendron bush at the nursery on Thursday, May 2, 2019. GEOFF FORESTER—Monitor staff

  • Richard Baker of Bristol says the rhododendron bush on his property has never looked this bad. Richard Baker / Courtesy

Monitor staff
Published: 5/2/2019 2:57:54 PM

A windy winter has left many of the region’s rhododendrons looking half-dead or even completely dead, but gardening experts have a piece of advice: Don’t panic!

“Don’t cut anything back yet. There’s a good chance that plants will resprout. Wait at least until the end of May or into June,” said Emma Erler, Education Center Program Coordinator with the UNH Cooperative Extension. “Buds are more cold-hardy than leaves. Even if leaves are dead and dried out, there’s a chance that buds are still alive, or there are dormant buds along the stem that may sprout.”

Len Brochu at Brochu Nursery in Concord agreed that plant owners shouldn’t be too quick in cutting off branches that look dead.

“Wait. I know it looks bad, but wait,” he said.

If you’re impatient, Brochu said you can tell whether individual branches are alive by scratching off a bit of the bark. If it looks green or bright underneath, it’s healthy; if it looks brown, the branch is probably dead.

This winter and early spring were hard on rhododendrons, Brochu said, not so much because of the cold but because of wind, which dried out leaves until they were left brown and crumpled.

“It’s been a bad year for a lot of things – farmers have lost hay fields, alfalfa fields. We didn’t have a lot of snow cover, just little storms that turned to ice, which doesn’t protect things,” Brochu said. “When it’s windy, it will desiccate plants.”

Such desiccation, or drying out, is more of a problem in winter because when the ground is frozen, roots can’t bring up more water to replace moisture lost from leaves.

Other types of plants have also been affected this year, especially junipers and arbovitae, Brochu said, but the problem is most noticeable with rhododendrons, judging by how widespread alarm seems to be.

“We’ve been getting at least half a dozen calls about it every day over the last four weeks. I got a couple more this morning,” Erler said.

Things are similar at the Monitor, which asked online readers whether they had seen this problem. We received no shortage of replies.

“My wife and I were just talking about this yesterday. It seems like most of the rhododendron bushes in our development are half-brown and we were wondering why that is,” said Dan Williams, who lives on Cranmore Ridge in Concord.

From Bristol, Richard Baker sent in a photo of one of his bushes looking as if the top four-fifths had been doused in herbicide.

“It’s been 20-plus years and I’ve never seen it like this. On occasion, we’ve had some brown on it, but that’s all,” he said.

On Tara Drive in Concord, Michael Mercier had a similar story: “They’re all dying in this neighborhood,” he said. “I’ve been here 12 years. Nothing like this. I was worried.”

Winter damage of rhododendrons does provide a lesson in plant evolution, helping to explain why deciduous trees go through the complexity and cost of shedding their leaves in the fall, and also explaining why most evergreens have long, skinny needles instead of leaves.

Broad, flat leaves have a high surface-to-volume ratio, which means they have a lot of surface area that can lose moisture when it’s cold and windy. Most broad-leafed trees have evolved to get rid of leaves in fall and grow new ones in spring, rather than keep them exposed to winter winds.

As for the presence of needles, they have much less surface area for the same volume than do leaves. Therefore, they lose less moisture. That is why pines, firs and other such trees don’t need to shed and re-grow their vegetation annually.

Coping with desiccation also explains why most broad-leafed evergreens like rhododendrons, plants that keep their leaves over winter, have evolved waxy surfaces on the leaves to reduce the amount of moisture that is lost.

(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com or on Twitter @GraniteGeek.)


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