This article is an expanded version of a social media post from Monday May 1st that had more comments and shares than normal, so we decided to include it in our weekly email and turned it into a blog. This topic hit a nerve with many on the South Shore and we wanted to get the word out to more people.
You are not alone if your roses and hydrangeas look like this. By all reports stem die back appears to be worse than normal on many rose bushes & hydrangeas across the South Shore.
Roses
These are some Drift Roses and a Hydrangea at my home garden. I suspect the minus 7 degree night this past February caused most of the damage.
In recent years, I’ve hardly had to prune out dead branches in my roses. This year I had to take some down very close to the ground. By now you can see which stems are brown and which ones are green. Basically cut back the obvious brown ones and keep the green ones. If you are like me and have a few in a row, some are not as bad as others but it makes sense aesthetically to prune them all to about the same height. In same cases, if the damage is severe enough, some roses might need to be replaced.
Back in the day, maybe 2-3 decades ago we would regularly advise all sorts of winter protection for roses. People would build structures around rose bushes and insulate them. Few people have time for that and the combo of roses being bred for stronger winter hardiness and global warming have lead to less need for protecting roses and it generally considered not worth it vs the cost of buying a new rose bush. Hard to predict this type of winter, but I think it came down to that one really cold 24-36 hours and no snow on the ground. Guessing we will also see damage to butterflies bushes, Hollies, cherry laurel and certain perennials not coming back. Surprisingly my Southern Magnolia looks to be doing fine.
Hydrangeas
For blue large leaf hydrangeas (botanically known as Hydrangea macrophylla), they look like dead sticks for a while. The spring of 2023 many hydrangeas only appear to be leafing out at the bottom. I usually leave them alone and resist pruning until early June or so. Hydrangeas “bloom on old wood”, meaning the flower stems emerge off of the dead looking sticks leftover from last year. I do not advise cutting blue hydrangeas back in the early spring since it could cause you to have less flowers. Living stems and dead ones look a lot alike in winter and spring. If you don’t want to wait until June and want to know if your hydrangeas stems are alive – try cutting some back or just scrape the outside bark back with a finger nail or knife, if you see green tissue then hold off cutting it back, since those sticks may produce flower stems. Cutting them back and/or them being killed back by a cold winter will mean an almost certain reduction in flower production in the current year. Each spring you can hold out hope they are just leafing out late. However, by June Hydrangeas will have leafed out as far up those stems are they likely will for the season and it is then safe to cut off the remaining woody stems for aesthetic reasons. Fingers crossed this year!
The good news – most white flowering panicle & smooth hydrangeas (Hydrangea paniculata and Hydrangea arborescens) can be cut back and they bloom no matter what.
Other plants to look out for?
Certain perennials may have suffered from the cold winter. Especially ones with woody stems. Plants like Lavender and possibly Russian Sage (usually very hardy) have woody stems and those stems may have died back a little further. I have only seen a limited sample size, but I did see damage to lavender in two gardens in Cohasset, including mine. Phenomenal Lavender was the variety in both cases and is supposed to be the most reliable and hardy of the newer lavenders by most accounts. I’m curious if other are experiencing the same thing?
Butterfly Bushes – we often see these not making it through cold winters with no snow. Rose-of-Sharon may have more dieback than normal. These leaf out late so don’t panic yet. Same for Hardy Hibiscus, they are not as cold hardy, but the also won’t start growing until it gets much warmer typically. I have been growing a Crape Myrtle in my home garden and I am nervous that may have suffered damage or severe dieback. My Cherry Laurel has more brown leaves than normal and I saw similar photos from a customer over the weekend. Surprisingly my Camelia and Southern Magnolia appear to be doing okay, but I am suspicious of the Camelia may still drop some of its evergreen leaves. Both of the those plants are supposed hardier than most of their southern counterparts, but I was thinking only global warming was allowing me to grow them this far north.
What To Do?
Besides waiting and doing a little pruning there is not a lot that can be done. We need to let Mother Nature take it’s course. You can fertilize your plants that have suffered in an effort to stimulate some new growth. Rose Tone is great for Roses. Any of the Espoma tones are good for outdoor plants, the exact type doesn’t matter too much to be honest. I typically do not feed my hydrangeas unless the leaves look yellow when they emerge.
If plants by early June are not up to your liking, they may need to be replaced. When in doubt stop in or email us photos and we are help to help you as time allows.
Chris Kennedy, is Massachusetts Certified Horticulturist and third generation owner of Kennedy’s Country Gardens in Scituate
Thank you. My knockout rose was knocked out. I also lost Blue Baron small-leaf rhododendron, part of Purple Gem rhododendron, two Dwarf Albert Spruce (in pots), and a Japanese Maple (3 years old) was severely damaged on one side. The lack of snow was the worse culprit. Looking forward to my visit to Kennedys soon!