Problems, pests and diseases

Hydrangea leaf problems

Last updated on April 7th, 2022

Our site is reader supported, this means we may earn a small commission from Amazon and other affiliates when you buy through links on our site.

Hydrangeas come in many varieties and are very easy to grow. You can choose from a big leaf variety or a panicle style depending on what type of display you want. But of course, regardless of the variety, the last thing you want is for your display to be hindered by leaf problems.

Common leaf problems can be caused by diseases, environmental problems, and even pests.

Environmental Problems

Environmental problems typically relate to issues of bad air circulation or problems when watering. If you don’t prune enough or you haven’t spaced your Hydrangea plants far enough apart they can grow too large for their space and cut off the air circulation, which leads to unnecessarily moist conditions. This often results in issues with an appearance that manifests on the leaves. 

Powdery mildew is a very common problem, it doesn’t harm the plant but does impact its appearance. If your Hydrangea isn’t producing flowers or you notice white powder on the leaves, it is likely powdery mildew that is causing the problem. You might see this when you have bad air circulation or very damp conditions and you need to get rid of any unnecessary humidity and increase the air circulation to help treat the problem. You can also spray plants with a fungicide that treats mildew at the first signs to help prevent it from spreading.

Bayer Garden Fungus Fighter Plus, 800 ml
  • Controls all major leaf diseases of roses and ornamental plants
  • Controls blackspot, mildew, rust, leaf spot, including box blight and white rust
  • Two effective active ingredients give contact and systemic action - fast acting and long lasting
  • Protects for up to 3 weeks
  • Use on houseplants, ornamental garden plants and selected edibles

Leaf Diseases

Leaf spot disease

The most common leaf disease that you will experience with your Hydrangea is called leaf spot disease. This is sometimes known as a foliar disease and is often caused by a fungal infection brought about by moist conditions. When you have particularly warm weather it can result in leaf spots. These spots are just that, spots that appear on the leaves.

Hydrangea leaf spot

The best way to treat this problem is to prevent it in the first place by making sure you only water your Hydrangea in the morning or in the evening, and that when you water, you do so at the base of the plant rather than from above. The reason for this is that any water remaining on your leaves after you have watered the plant (or after heavy rain) can remain in place, build up, and result in fungus. If you have watered or it has rained and there is water on the leaves you can gently shake your plant to get them off.

But if the problem is already there a fungicide will help you get rid of it.

Bacterial leaf spot

Similarly, your Hydrangea might be suffering from bacterial leaf spot. This doesn’t form the soft leaf spots but rather a discolouration on your leaves. This one is more problematic than a fungal infection because it can actually kill your plant. The symptoms can manifest in a multitude of ways and they start with black-edged lesions on the leaves or dark brown lesions with a yellow tinge. Most of the time the spots are irregular and quite small. You might notice them on the bottom parts of the leaves or the very top. Eventually, they will dry, turn brown, and fall off.

Hydrangea pests and diseases

Wet and cool conditions encourage bacterial growth and the bacteria can get splashed on the leaves of your Hydrangea from other debris or nearby plants. If you have already noticed the symptoms you can use a bactericide to treat the condition and prevent it from spreading, not only to more parts of your Hydrangea but to other plants in the nearby vicinity.


Pests that affect the leaves of your Hydrangea

Look out for pests in the garden such as aphids, slugs and snails

There are problems with pests now and again that can affect the leaves. Some pests aren’t as intrusive as other pests such as spiders. If you see spiders on your Hydrangea, if you can, leave them alone because they will feed on other insects. However, spider mites actually feed off of the leaves and harm the plant. The problem with spider mites is that most people don’t see them until the problem is quite significant because they are so small. You have to get up close to the leaves to notice the little small, red bugs. You can spray them off with water when you see them, mixtures of water and citrus oils as deterrents, or you can use pesticides.

Miracle-Gro Bug Clear Ultra Gun 1Ltr
  • Kills all major insect pests, including whitefly, greenfly, black fly, red spider mite, caterpillars and lily beetle, scale insects and mealy bugs For use on flowers, fruit and vegetables 1 ltr
  • For use on flowers, fruit and vegetables
  • 1 Litre
  • The Bug Clear Ultra Gun is suitable for both indoors and outdoors use including conservatories.

The same issue comes from aphids and whiteflies. These are equally small and difficult to see, they remove the sap from the tissues in the leaves until the leaves turn yellow and fall off prematurely. You can remove these with a mixture of water and dish soap but don’t do it when the sun is out and overhead or it can burn your leaves. You can also just use water with high pressure to wash them off the leaves, or a pesticide.


Whatever the leaf problem is with your Hydrangea, the key is to fix it as soon as you can. This prevents any harmful issues from getting worse.

Image credits – Shutterstock.com

Last update on 2022-03-17 / Affiliate links / Images from Amazon Product Advertising API

Welcome to my site, my name is John and I have been lucky enough to work in horticultural nurseries for over 15 years in the UK. As the founder and editor as well as researcher, I have a City & Guilds Horticultural Qualifications which I proudly display on our About us page. I now work full time on this website where I review the very best gardening products and tools and write reliable gardening guides. Behind this site is an actual real person who has worked and has experience with the types of products we review as well as years of knowledge on the topics we cover from actual experience. You can reach out to me at john@pyracantha.co.uk

Write A Comment