Hello;

Thanks for your Hydrangea question. From your photos the cause of the yellowing leaves may be due to the increased aphid population. Try washing them off with a gentle spay
of water to see if that helps.

 Additional causes may be due to watering conditions, nutrient deficiency, or soil conditions.

  I have listed several links below that go into more details concerning Hydrangea leaf yellowing and Aphid treatments. If you should use the pesticide treatments make sure it is listed for use on Hydrangeas and Always Read and Follow the Label Directions! In addition listed is your County OSU Extension Service should you wish to contact them for
additional information and help.

   Thank you again for allowing us to
help you with your gardening questions. Here are some other helpful websites that may be of interest to you:

BYGL Newsletter: http://bygl.osu.edu/
OSUE Fact Sheets: http://ohioline.osu.edu State
Master Gardener Volunteer website - http://mastergardener.osu.edu

Ask-An-Expert website - https://extension.osu.edu/ask-an-expert

Ask-A-Master Gardener website -
https://extension.osu.edu/https%3A/extension.osu.edu/ask-an-expert/ask-master-gardener-volunteer

Butler County OSU Extension Office

1802 Princeton Road 

Suite 400
Hamilton, OH 45011

Phone: <personal data hidden>

Fax:

<personal data hidden>

Directions to Butler County Extension Office

https://gardenforindoor.com/why-hydrangea-leaves-turning-yellow/


https://www.thespruce.com/hydrangea-leaves-turning-yellow-7564733


https://worldofgardenplants.com/hydrangea-yellow-leaves/


https://florgeous.com/hydrangea-leaves-turning-yellow/


https://www.plantindex.com/hydrangea-yellow-leaves/


https://thegardeningdad.com/proven-ways-to-get-rid-of-aphids-on-hydrangea/