Long, Cold Winter Leading To Gardening Woes – WBUR


I’m Robin Young. It’s HERE AND NOW. So, gardeners in parts of the country are storming landscape supply stores to replace drought-starved plants with pebbles and lawn ornaments. But other parts of the country, it’s Mother Nature that’s still storming, and the effect has been pretty devastating.

From Evergreens in the Northeast to creeping fig plants in South Carolina, winter has taken its toll. So what should gardeners look for? What should they be doing? For help we turn to gardening guru Mike McGrath, host of WHYY’s YOU BET YOUR GARDEN. Mike, welcome back.

MIKE MCGRATH, BYLINE: Robin, it’s always a pleasure to speak with you.

YOUNG: Except wow, what a winter. Nearly every state east of the Rockies has had colder-than-average winter, a higher-than-average number of days where the temperature was below freezing. So just tick through some of the things you’re hearing from your listeners across the country.

MCGRATH: Well, I’m hearing that, and they’re wondering what effects these cold winters have had on their perennial plants, and then they’re hoping for a silver lining, that the cold winter has knocked off some of the invasive insects and really nasty blights and mildews that have only appeared in the past three or four years to really devastate certain plants and gardens.

YOUNG: Well, start there. Do you think the cold has knocked off some of those woolly adelgids, or whatever they are, the things that have been affecting plants across the country?

MCGRATH: Excellent choice, Robin.

YOUNG: Thank you.

MCGRATH: Because I think the woolly adelgid is the only insect that has been affected negatively or positively. The woolly adelgid is a great example of the effects of climate change. Hemlocks are trees that typically grow in cold climates, but people have extended their range into kind of iffy areas, because they’re such wonderful trees. Woolly adelgids are creatures of warm environments that can’t stand the cold.

So we had a combination of trees that were maybe in a place a little bit too warm and insects who liked it warm. So this winter dealt a double blow to the adelgid. First, the cold was bad for that insect. It must have knocked their numbers back significantly, because it just doesn’t appear naturally in areas that get that cold. But the trees, for a hemlock, a cold winter is like a Flintstone’s vitamin. They are stronger than ever now. So that’s a really good example of a tree that needed more chilling and an insect that just needed to chill out.

YOUNG: Well, but Mike, can trees get too much chilling? For instance, I have a hemlock that has started to get that yellowing on the edges, and it was explained to me that hemlocks can only – and evergreens, these beautiful green trees, can only go so long with the ground frozen, and they can’t get any moisture. So can’t…

MCGRATH: Eh, mez-a-mez(ph). It’s – that’s the kind of yellowing that’s going to disappear as soon as it warms up. Evergreens are some of the hardiest trees.


MCGRATH: I mean, that’s where all your Alpine plants are, up in Zone 3, where you and I wouldn’t make it 20 minutes.

YOUNG: But then which plants are getting the winter burn? Which plants just had too much this winter?

MCGRATH: It’s not the plant, Robin. It’s your snow cover. The worst thing that can happen to a garden is a freezing cold winter without snow cover. But once you get that snow cover, and especially, we’ve always told people if it starts snowing in November, and you can always see white on your ground until April, you are going to have one of your best gardens and landscapes ever, because the snow is a perfect insulator.

YOUNG: It’s a mulch.

MCGRATH: It may be minus five in the air up top, but down underneath that snow cover, not only is it right at 32, but the temperature isn’t wavering. It’s not that roller coaster that can be so bad, the freezing and thawing can pop plants out of the ground. They’ve got a blankie, God’s blankie. They love being under snow.


YOUNG: But stay with snow for just a second. What about snow higher up on plants? I’ve been told that, you know, don’t remove it. Let’s say you’ve got a beautiful, tall, thin, hemlock, but it’s completely bent to the ground, or lilac branches that are bent to the ground by snow. You shouldn’t try to pull them out and shake them, just let it melt?

MCGRATH: It’s really hard to do. I had the same situation with a gold dust plant. I had actually forgotten I had a blue holly in front of my house, because it is totally – it is now a prostrate blue holly, hugging the ground. And I know it’s going to come back, and I still want to go out and, quote, “help” it. But you’re absolutely right. Plants have this wonderful flexibility. Once they’re warm again, once the sap is flowing, what is now kind of a steel rail is going to turn into more like a rubber band.

And when that happens, when that sap starts flowing, then the tree, the shrub can do what comes naturally, which is to reach towards the sun. If we try to change their angle when the sap is frozen solid inside, you know, it’s like breaking an ice pop in half.

YOUNG: Well, Mike, we had a premise here, so we have to make sure the premise is true. I mean, you’ve say that the snow can actually act as insulation and sort of mulch, but we are hearing that it was a devastating winter. So where and to what plants – you know, what plants have been affected?

MCGRATH: You, me. It was a – the winter tried to kill us. Weren’t you paying attention?


YOUNG: But in the garden, where – I mean, you mentioned the fig plants. Where should people be looking at plants and thinking that maybe it may have been too tough a winter? And when do you know when to pull a plant out, when to give it a chance?

MCGRATH: Well, I think people are much too reluctant to take out dead plants. A lot of times, people who have this premise that maybe it’s going to come back. After they wait four or five years, they sudden realize they do have an Adams Family garden. But these kind of winters, the damage is done during the ice storms, when the trees are uprooted, or when branches are knocked off.

Really, once the storm is over, the long-term damage can then only occur to plants that were iffy to begin with, people planting warm-season plants in colder zones, crepe myrtle being a great example, a plant you only used to see down South. And it kept creeping up, creeping up, creeping up. I wouldn’t be surprised to see a crepe myrtle in Boston, although…

YOUNG: It would scare the heck out of me.

MCGRATH: Well, they’re kind of creepy plants.

YOUNG: Creeping up on me.

MCGRATH: But they’re not supposed to be planted north of Washington, D.C. But they have been, and every once in a while, people are going to have that 10th-year winter. I tell people who live in the city of Philadelphia, in a community garden, in the heat sink of the city, they can leave rosemary plants outside the ground over winter. Nine years out of 10, those plants are going to survive. Well, guess what this year was? This was the 10th year.

So you have to eat that if you’re growing tender plants. But for the majority of plants that are in their right USDA growing zone, that are in the right climate, it seems counterintuitive, but they are going to respond brilliantly once spring arrives. There is nothing more protective than a mulch of snow, and there’s nothing more spring-like than to have snow melt, the ground be saturated as the sun begins to warm that soil.


MCGRATH: Those are all the cues for a fabulous spring.

YOUNG: Hope springs eternal, then. And we understand, be patient, wait until May to see whether something is alive or dead. Scrape a little bit off the bark, and if it’s green, you’re good to go?

MCGRATH: Just wait and see. Leave it out there, and plants are stronger than we give them credit for.

YOUNG: Mike McGrath, host of WHYY’s nationally syndicated YOU BET YOUR GARDEN show. Mike, thanks, as always.

MCGRATH: Always a pleasure, Robin. Thank you.

YOUNG: I feel better already. You’re listening to HERE AND NOW. Transcript provided by NPR, Copyright NPR.


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