If you have purple leaves on your hydrangea plant it could be indicative of a problem. Suddenly seeing purple on your leaves is enough to make you go into a panic, especially when that’s not a normal color. First, though, there are some varieties that produce a purple tinge and some start to turn purple into the fall. However it can also be a sign of when something is not right, especially if the leaves are usually a lush green.

Why are my hydrangea leaves turning purple?

Purple colors on your hydrangea leaves could be indicative of a very simple environmental issue or a fungal disease.

Fungal diseases

Fungal diseases will produce purple spots on your hydrangea leaves. If you have purple spots it might be indicative of Cercospora leaf spot, a common leaf fungus. Rest assured that this particular disease won’t kill your plant in almost all cases but it might cause the leaves that are affected to shred. If this happens it will weaken your overall hydrangea and reduce the number of buds that grow the following season.

With this, you might notice small purple or brown spots that start around the base of your plant and spread not only upward but outward especially as water splashes on the leaves and moves the spores to other locations. The spotting patterns on your leaves are going to vary based on the type of hydrangea. You can slow down the spread of this disease by simply cleaning up any leaves that fall down and making sure that when you water your hydrangea you water it at the base and not on the leaves. If you water on the leaves you will only help further spread the disease.

In some cases, it might help you to remove up to one-third of the branches if you have a very tightly packed hydrangea because this will help increase the air circulation which will prevent the spores from germinating as quickly.

If most of your leaves are purple and the disease is very severe, you can add an application every two weeks of a chemical fungicide. Many garden centres sell fungicide sprays which are well worth trying.

Phosphorus deficiency

Another reason that your hydrangea leaves might be turning purple is simply because of a phosphorus deficiency. This is their way of telling you that they don’t have enough phosphorus components in the soil. This is something that happens when Gardner’s rush to alter the pH of the soil very quickly so as to change the flower color of the hydrangea. In some cases you might accidentally let your pH drop so low, so fast, that other chemical compounds in the soil bind up all that phosphorus which means the plant can’t use it. You can start by checking your soil pH levels. If you have acidic soil below 6.0 the aluminium might be tying up the phosphorus. If you have alkaline soil above 7.0 the calcium or magnesium might be binding with the phosphorus.

To fix this simply alter the pH of the soil little by little to free up more phosphorus. If, after a few weeks, you don’t see a noticeable difference in your plant it might be best to add a phosphorus fertilizer around the roots.

Weather

Weather can influence the color of your hydrangea leaves as well leaving a lot of purple hues. If it’s cool weather at the end of the growing season your plant might start going into dormancy prematurely and that will cause the purple color to show through as the green colors stop producing chlorophyll.

Frost damage so leave purple discolouration on your hydrangea leaves. If you see it simply remove the bad leaves once they have dried out. If there are partially injured purple leaves, let them be until the new leaves have formed.

Image by Jan Haerer from Pixabay