One of my endless summer hydrangeas that was planted last spring came back with very thick and distorted new growth. New growth appears pale green and stunted. Leaves are small, thick, narrow and cupped. Was wondering if this condition may be caused by herbicide poisoning or something else and what, if anything I could do to ensure its survival.

It sounds like it could be herbicide injury. I assume you know that a herbicide was used in its vicinity since you mentioned it?

I came across herbicide damage while searching the internet for a cause. I did put a pre-emergent on my yard in late Feb. I used a spreader and some of the fertilizer/herbicide could have gotten over in my bed. The plant that was affected is the closest one to the yard. Is there anything I can do to save it or should I just purchase another one?

If it was pre-emergent I wouldn't have thought it would do that to an established plant. Do you recall the product? I would just leave it alone, it may recover. Also check it for any insects where the leaves are cupped. If you can get a picture to post here it may help.

Ok, I've sprayed some other stuff on the grass as well. I'll find out what it is when I get home and post. Also, I'll take a picture this afternoon and post it. Thanks for your help. I've been watering almost daily because it's already 90 degrees here (Kentucky), and I thought it might flush out what is affecting it.

Give it a good deep watering, to wash any chemicals and salts from any fertilizers, or salts from water down.
It will re-coop, with new growth. Just give it some time. 👍👍

Deep watering, a couple times a year, is a thing to practice for heathy plants. 👍👍

Ta ta 😀
😎😎😎

Watering may actually cause the herbicide to spread further in the soil and affect other plants, plus herbicides can be less effective in dry conditions. So flushing isn't necessarily the way to go but if course if you need to water you need to water.

This is a picture I took this afternoon of the stunted/distorted hydrangea.

Just a thought but I would remove the rock mulch, you are creating a heat sink.

If there are no insects for sure (e.g. thrips or aphids) I would suspect the herbicide. Did you figure out what was used?

This is what I used in early Aprilto try and defeat the yellow nutsedge that was gaining a foothold in my lawn. Also, I sprayed some Bauer Advanced Insect, Disease & Mite Control on the leaves about two weeks ago because snails were eating the new growth, but it rained the day that I sprayed it, so I thought it probably washed off. I also used some Espoma Organc Soil Acidifier to lower the pH. I've been known to love my plants to death. lol. Only the Image product was sprayed on the lawn. The other products were put in the hydrangea.

I was afraid the black lava rock may be too hot, but they only receive about 3-4 hrs direct sun. Should I pull the lava rock back and put down a lighter colored mulch?

I would get rid of the lava rock and use some sort of shredded bark, pine needles etc

So the herbicide was post-rather than pre-emergent. Here's a picture of a plant treated with Quinclorac, one of the ingredients in your product:

https://www.uaex.edu/farm-ranc...

Unless I'm looking at the wrong Bayer product (contains imidacloprid, tau-fluvalinate and tebuconazole) it does not contain anything that would control slugs or snails (which are not insects but molluscs).

Sooby, thank you so much for the valuable info. I did put a pre-emergent on my lawn in late Feb. as well as the post emergent which was put on in. April ; however, the pre was a granual put on with a spreader. I have since thrown the bag away, so I'm not certain what the active ingredients were. I will try to figure it out and post if I can.

Thanks for the info regarding the snails. I sort of sprayed the Bayer on the fly hoping it would at least repel the snails. What would you suggest using to keep them away? I have a lot of them, and I've noticed them eating away at the new growth on my hydrangeas as well as my violas and mums. My wife thinks the snail are cute, so maybe something that might deter them from eating specific plants would be best. lol

I'm going to take your advice and leave the hydrangea alone and hope for the best (so difficult for me to do).

I am posting a pic of the 4 hydrangeas together so you can see how the one isn't doing as well as the others. I thought the pic might be beneficial. Please let me know if it sheds any light on the subject. Again, thank you so much for your time and for your advice.

I would not worry about the leaves. At the end of the growing season, the leaves will dry out and be replaced with new ones in Spring 2019.

I would vote for removing the rocks. They can cook the roots underneath and make the plants be quite unpleasant. If there was a way to tell how safe dyed mulches are, I would say to use black dyed mulch but no, do not go that way. I do like the way things look with the dark/black motif of the mulch and the small tree-like shrub's dark leaves.

Just use 2-4" of organic mulch at all times year around.

Water the soil early in the mornings (6am ish?) from the root ball outwards. Try not to get the leaves wet if you can in order to prevent fungal infections. To make sure you do not go overboard watering, insert a finger into the ground to a depth of 4" or so... and water if the soil feels dry or almost dry.

It seems a long way from the lawn for spray drift (for the post emergent). It seems unlikely the pre-emergent would have got that far especiallty as granules. It's also less likely to have done the damage than spray drift from the post-emergent (assuming it was a spray?). If it was not a spray then we'd need to look up whether those ingredients are soil-active or not.

As for the snails, there are molluscicides you can buy, I don't know what would be available in your area or what your concerns might be with pets/wildlife/kids getting into them. One thing to avoid is watering the plants in the evenings because that keeps conditions more moist at night, although that perhaps applies more to slugs than snails because snails have more protection from the sun and dehydration. Avoid watering too often, infrequent but heavier watering is best for plants as well.