Getting Rid of Black Spots on Hydrangea Stems for Good

As a hydrangea lover, I was heartbroken when black spots started appearing on my hydrangea’s gorgeous green stems. Those lacecap blooms were stunning, but the black stems ruined the look. After researching and trying different methods, I finally found a way to banish those pesky spots for good.

What Causes Black Spots on Hydrangea Stems?

Hydrangeas are prone to fungal diseases that cause black spots on the leaves and stems There are two main culprits

• Cercospora leaf spot – Caused by excessive moisture on the leaves from overhead watering or rain. Small angular black spots appear first on the leaves then spread to the stems.

• Anthracnose – Another fungal disease thrives in hot, humid weather. It starts with big black spots that run together on the leaves and stems.

I thought cercospora leaf spot was the cause because the spots on my hydrangeas were small and spread out. Both diseases grow best when it rains a lot, which keeps the plant from drying out.

How to Prevent Black Spots on Hydrangeas

Here are some tips to avoid black spots in the first place:

• Water at the base of the plant to keep moisture off the leaves.

• Prune out old stems to improve air circulation.

• Avoid overcrowding plants.

• Use drip irrigation instead of overhead sprinklers.

• Apply preventative fungicide sprays like copper soap early in the season.

• Clean up fallen leaves and debris around plants.

Fungal spores can still get into your hydrangeas even if you take good care of them. It’s important to know how to handle any spots that do show up.

Getting Rid of Existing Black Spots on Hydrangea Stems

If those dreaded black spots appear, take action ASAP with these steps:

• Remove and throw out badly infected leaves and stems. This instantly decreases the spore load.

• Apply copper fungicide spray thoroughly on leaves, stems and even the ground around plants. Repeat applications are likely needed.

• Improve air circulation with judicious pruning. But don’t cut off more than a third of the stems, or the flowers might not bloom as much.

I tried these measures for a couple seasons with moderate results. The spots would disappear for a while only to return later in the summer. I realized the crowded, consistently damp location of my hydrangeas promoted fungus.

When to Remove Hydrangeas with Severe Black Spots

After battling black spots on my hydrangea stems for years, I finally had to admit defeat. The constant pruning, spraying, and stress just wasn’t worth it for a few flowers.

Here are signs it’s time to remove infected hydrangeas:

• Black spots persist despite diligent treatment.

• Leaves and flowers are also affected, reducing blooms.

• Too much moisture causes frequent recurrence.

• The frustration outweighs the joy of growing them.

Digging up my diseased hydrangeas left room for other plants better suited for that wet area. I still admire beautiful hydrangeas, but now choose disease-resistant varieties like panicle hydrangeas planted in drier spots.

With some trial and error, you may discover cultural or chemical controls that eliminate spots on your hydrangeas. But if the battle becomes too difficult, replacement could be the best solution. Don’t let black spots ruin your love for gardening!