Limelight Hydrangeas

Question: I’m at a complete loss so I was hoping a garden expert could help identify the issue with my limelight hydrangeas. I have over 30 panicle hydrangeas around the house and every other ones are doing so well except for the five limelights that are in the same area. They all look sick. The tip of each branch has these skinny, sickly green looking leaves and it doesn’t look like it’s going to form buds. Last year, only one of them had this issue but this year all five of them are looking like the pictures I have attached here. 

Additional information: we do not use any types of herbicides around our plants.

responder: An Ask Extension Expert Replied July 11, 2024, 12:14 PM EDT
response: Hi Liam, I'm sorry to hear about your hydrangeas! The narrow "shoestring" effect on the leaves is characteristic of hormonal disruption, the most common cause of which are herbicides.  You mention that you don't use herbicides near the plants (which is great)--do you know if anything has ever been applied to the rocks further away from the shrubs?  Certain products (often labeled "Ground Clear" or similar) can contain active ingredients that are both highly mobile and temporally persistent in the soil, so even a remote treatment, under the right circumstances, could be problematic. Can you also let me know how long these plants have been in the ground, and how you typically care for them? Cordially, John

responder: The Question Asker Replied July 11, 2024, 2:39 PM EDT
response: Hi John, Thank you for getting back to me so quickly. I don’t know if anything has ever been applied to the rocks further away from the plants. My neighbors sometimes spray their weeds but I don’t know what kind of weed killer they use, and it didn’t even dawn on me that the weed killer spray they use could potentially have caused the issue because it’s at least 5-7 feet away.   To answer your second question, these plants have been in the ground for about 3 years. We planted them Fall 2021, and everything was beautiful Summer 2022. Then starting last year, Summer 2023, I started to notice this issue with one of the plants. In terms of care, I fertilize them with the Rose Tone by Espoma in early Spring and late Fall. I also prune them in early Spring when I start seeing new growth on them.  Thank you,  Liam   On Jul 11, 2024, at 10:14 AM, Ask Extension <<personal data hidden>> wrote:   ﻿

responder: An Ask Extension Expert Replied July 11, 2024, 4:32 PM EDT
response: Thank you. Three years in the ground would be long enough for the roots to be distributed fairly widely, including up to that far from the main plant.  Additionally, herbicides containing the active ingredients imazapic and imazapyr (among others) are very mobile in the soil and could make their way to sensitive plants over time.   If the rocks that I can see in the background of the photo were treated with a groundclear type product, that could definitely be causing the issue your seeing.  Luckily, for damage severity as in the photo, woody plants are usually able to grow out of it without issue.  Long-term, if continued herbicide use is anticipated, you may want to install a root barrier to prevent roots (and other things) crossing the property line. I hope this is helpful. Cordially, John

responder: The Question Asker Replied July 13, 2024, 6:29 PM EDT
response: Hi John, I do appreciate you taking the time to look into my question and responding so quickly. I’m glad to hear it wasn’t a disease that would spread and affect some of the other hydrangeas near by like chlorosis or yellow asters. Again, your help is very much appreciated.   Take good care,  Liam On Jul 11, 2024, at 2:32 PM, Ask Extension <<personal data hidden>> wrote:   ﻿