Have rhododendrons suffering from winter burn? Here's how to revive them and to know when to quit.
The PJM rhododendron, a small-leaved one, is in full flower and the leaves look great.
Dave Epstein
But some of the larger-leaf rhododendrons, hollies and even some of the cedars are not as healthy because such broader leaf evergreens lose moisture throughout the winter. This is one of the reasons why the rhododendrons curl when the temperature gets to 32 degrees. They are trying to protect that moisture loss. If you notice curling in the growing season, there's likely a problem, perhaps a disease or an insect attacking your plant.
You'll also likely notice crispy brown leaves (or needles), especially at the top of the plants where the damage seems most prevalent. Rhododendrons have a reserved bud on the branches and with adequate water, some of these branches should releaf this spring and into the early summer. If, however, the branches themselves are very brittle and if you scratch them with your thumbnail and you see no green at all, it is likely there will be dieback, and it could be significant.
Advertisement
Some broader leaf rhododendrons aren't looking as well this spring as the smaller-leaf ones.
Dave Epstein
A smaller-leaved rhododendron, which is blooming much smaller this spring due to various factors.
Dave Epstein
broadleaf
There are a few factors that likely have contributed to the widespread winter damage of broadleafthem evergreens. First and foremost, would be the fact that we had a drought going into the winter and lasting throughout the cold season. Rhododendrons are shallow-rooted plants, so their roots don't go deep enough to tap into moisture deep in the ground. This very dry topsoil likely put a lot of stress on these plants as we went into winter.
We also had typical cold weather in December, January, and February. And there wasn't much snow cover at the beginning when the cold arrived, so the ground froze deeply, preventing these shallow-rooted plants from accessing the limited available moisture. The winter sun, especially on plants that have a southern exposure, could have also contributed to the plant burn. The reflecting light off snow can be another factor, drawing moisture out of the plant's leaves.
A holly bush showing signs of winter burn on Friday.
Dave Epstein
So now you might be wondering what you can do to help the plants. First of all, be patient. It will take a while for new buds to form and open up. You can help them along by being sure that the soil has adequate moisture. This doesn't mean soaking the ground, however, because you could create root rot if the ground is too wet.
You could try a quarter cup of an organic liquid fertilizer along with some organic granular fertilizer, and incorporate that into the soil with several gallons of water. Adding some compost or leaf mulch to the area can also help improve the soil health.
Advertisement
If we have average precipitation through May, the drought won't worsen, but if things dry out significantly, you might have to augment with your own watering again into the summer.
I would wait until the first week of June before cutting any branches unless you're 100 percent sure they're dead. If at that point your tolerance for what you're looking at and how your plant has responded is low, then remove the plant and replace it with something else. Look around your yard or others for plants that have fared well this winter, and that might give you an idea of what you can replace it with. Think of it this way: A dead plant presents a new opportunity to bring renewed beauty to your landscape. Happy gardening!
Have more gardening questions for Dave? Send them to weather@globe.com, and we will include them in an upcoming column from Dave.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Boston Globe
14-05-2025
- Boston Globe
After a spectacular 2024, are hydrangeas set for another strong comeback this year?
To understand why there's such a difference from year to year in just how prolific the hydrangea blooms will be, you need to understand a little bit about the habit of these quintessential New England plants. There are three main varieties of hydrangea that most people have in their yards. Macrophylla, which are the large leaf mop heads, mostly blue or pink plants. Then there's the Annabelle and the paniculata. These last two bloom on what is called 'new wood' or this year's growth. This is why for those particular categories of plants, you can prune them hard in late winter and early spring and still get plenty of flowers. The density of your blooms on those types of plants is going to be more related to the spring and summer weather, as well as whether you have adequate soil nutrients to produce flowers. Advertisement But it's different for the mop head variety. Although there have been new varieties developed over the years that bloom on new wood, the best blooms in this group occur on last year's growth. This means that the flower buds form in the late summer and early fall of the previous year and sit out all winter long exposed to the elements. Macrophylla hydrangea, or the mophead variety like nikko blue, are showing early budding this time of year. Dave Epstein In a cold, particularly dry and windy winter, those bloom buds can get desiccated and will not flower. The plant itself is not dead, and you'll often see new growth sprouting from the ground, which will form flower buds for the next year, but you'll miss the existing year. This is what happened in 2023. Because the winter of 2023-24 was so mild, nearly all of the bloom buds survived, and thus we had an Because of the drought last fall and the first part of the winter, there's likely some damage to the flower buds. Additionally, those plants that are marginally hardy probably will not bloom this year because of the average cold we saw in January and February. Advertisement Blue hydrangeas in Lexington last summer. Joanne Rathe Strohmeyer/Globe Staff I have one plant that bloomed last summer that had not bloomed for over a decade, and it looks like it's not going to bloom this year. The bottom line is that I think it's going to be a very good year for hydrangeas, likely not as good as last year, but for some plants, it's going to be pretty close, so get ready to enjoy another round of a local favorite in the garden. A Hydrangea blossom in a Quincy front yard. Matthew J. Lee/Globe Staff You can see the leftover flowers from 2024 just as early buds have popped up in mid-May. You can cut the spent flowers, but be careful not to cut viable buds. Dave Epstein Paniculata hydrangea that were pruned in late winter are now showing new growth, which will flower in late summer. Dave Epstein Have a gardening question for Dave? Send them to weather@ and we will include them in an upcoming column from Dave.
Boston Globe
26-04-2025
- Boston Globe
Have rhododendrons suffering from winter burn? Here's how to revive them and to know when to quit.
The PJM rhododendron, a small-leaved one, is in full flower and the leaves look great. Dave Epstein But some of the larger-leaf rhododendrons, hollies and even some of the cedars are not as healthy because such broader leaf evergreens lose moisture throughout the winter. This is one of the reasons why the rhododendrons curl when the temperature gets to 32 degrees. They are trying to protect that moisture loss. If you notice curling in the growing season, there's likely a problem, perhaps a disease or an insect attacking your plant. You'll also likely notice crispy brown leaves (or needles), especially at the top of the plants where the damage seems most prevalent. Rhododendrons have a reserved bud on the branches and with adequate water, some of these branches should releaf this spring and into the early summer. If, however, the branches themselves are very brittle and if you scratch them with your thumbnail and you see no green at all, it is likely there will be dieback, and it could be significant. Advertisement Some broader leaf rhododendrons aren't looking as well this spring as the smaller-leaf ones. Dave Epstein A smaller-leaved rhododendron, which is blooming much smaller this spring due to various factors. Dave Epstein broadleaf There are a few factors that likely have contributed to the widespread winter damage of broadleafthem evergreens. First and foremost, would be the fact that we had a drought going into the winter and lasting throughout the cold season. Rhododendrons are shallow-rooted plants, so their roots don't go deep enough to tap into moisture deep in the ground. This very dry topsoil likely put a lot of stress on these plants as we went into winter. We also had typical cold weather in December, January, and February. And there wasn't much snow cover at the beginning when the cold arrived, so the ground froze deeply, preventing these shallow-rooted plants from accessing the limited available moisture. The winter sun, especially on plants that have a southern exposure, could have also contributed to the plant burn. The reflecting light off snow can be another factor, drawing moisture out of the plant's leaves. A holly bush showing signs of winter burn on Friday. Dave Epstein So now you might be wondering what you can do to help the plants. First of all, be patient. It will take a while for new buds to form and open up. You can help them along by being sure that the soil has adequate moisture. This doesn't mean soaking the ground, however, because you could create root rot if the ground is too wet. You could try a quarter cup of an organic liquid fertilizer along with some organic granular fertilizer, and incorporate that into the soil with several gallons of water. Adding some compost or leaf mulch to the area can also help improve the soil health. Advertisement If we have average precipitation through May, the drought won't worsen, but if things dry out significantly, you might have to augment with your own watering again into the summer. I would wait until the first week of June before cutting any branches unless you're 100 percent sure they're dead. If at that point your tolerance for what you're looking at and how your plant has responded is low, then remove the plant and replace it with something else. Look around your yard or others for plants that have fared well this winter, and that might give you an idea of what you can replace it with. Think of it this way: A dead plant presents a new opportunity to bring renewed beauty to your landscape. Happy gardening! Have more gardening questions for Dave? Send them to weather@ and we will include them in an upcoming column from Dave.
Boston Globe
09-04-2025
- Boston Globe
It's not too early to work the spring soil. Here are some tips for a flourishing April garden.
It's not too late to start your warm-weather crops inside. For example, tomatoes, peppers, and eggplants can still be started, although the plants may be a bit small when they're ready to go out later in May. Use a grow light and a good starter mix to ensure even and non-leggy plants. If you want to put things straight in the ground from seed, peas, carrots, radishes, Asian greens, turnips, beets, and fava beans can all be planted right now. If temperatures look like they're going to go under 28 degrees, you can always throw a sheet over the seed area for a night or two. You'll also find lettuce and other cold, hardy crops already out in the garden centers. Those can go directly in the ground. Advertisement Annuals It's too early for your warm-weather annuals, such as geraniums or impatiens, but pansies, primula, and some violets will take a freeze. Dianthus calendula and snapdragon can be put out as long as the temperature looks like it's not going to go under 30. Advertisement Primula are good flowers to plant during April. Dave Epstein Perennials This is a great month to divide perennials. Anything that flowers from mid-June onward can be divided now. This also includes hosta and fern, which will benefit from some dividing. I've even moved plants this time of the year that flower in May, and as long as there's adequate water, they don't seem to miss a beat. Trees and shrubs Inevitably, I need to move some of my trees and shrubs around, especially newer ones that may not have been placed correctly. April is a perfect time to pick things up and put them in a new place. There's adequate moisture in the ground and plenty of time for the roots to form. Once things leaf out, it gets a lot harder to move them without some shock, and the risk of dying goes way up. Lawns Over the past couple of decades, I've taken out over 50 percent of my lawn and replaced it with perennials or other ground covers. Nevertheless, I do have some grass, and this is a good time to put down spring fertilizers. Try to be organic with whatever you do. Many of the harsher chemicals are terrible for the environment. A thick, adequately watered lawn will not succumb to the crabgrass later in the summer. If you have to use pre-emergents, follow the directions and use them sparingly. Starting a lawn in the spring is not advisable; wait until the fall to do that. You could overseed later this month on an existing lawn to thicken it up. Advertisement Soil health It's always a good idea to get your soil tested if you're not sure what you need. I also know that many of you are going to put down fertilizer without testing. A general all-purpose organic fertilizer with slow-release nitrogen is best. Try to work it into the top 4 inches of the soil and put it down before the mulch. If you have containers where you're growing flowers or vegetables, you can recharge that soil with some organic compost or simply add organic fertilizer at the recommended rate. If your soil's been in a container for several years, I recommend starting over and evenly spreading the soil in the garden or over the lawn. It'll work itself in overtime. Garlic shoots sprout up out of the soil. Suzanne Kreiter/Globe Staff Every gardening season is different, and the challenges ahead can be anything from a late cold snap to too much rain to too little, but gardening season is here, and it's time to get out there.
