Should I cut the whole plant back if it has mildew?

If the foliage looks terrible, you can cut it back to the ground. The plant will often send up fresh, healthy leaves in the fall.

Is powdery mildew contagious to other plants?

Yes, it spreads easily through the air. Keep an eye on neighboring plants and improve airflow in the whole garden bed.

Why are there white powdery spots on my Columbine?

Check these first

Rub a spot to see if it wipes off like powder.
Check if the plant is crowded by other flowers.
Ensure the plant is not sitting in stagnant air.

Likely causes

Powdery Mildew
Most likely
How to tell: White, flour like spots appear on the leaves and stems. In severe cases, the entire leaf may turn white and eventually wither.
What to do: Prune away the most heavily infected leaves to improve air circulation. Spray the remaining foliage with a mixture of one tablespoon of baking soda in a gallon of water.
Water Splash
Possible
How to tell: Small brown or white spots appear after heavy rain or overhead watering. This is often just soil splashing up onto the leaves.
What to do: Apply a layer of mulch around the base of the plant to prevent soil from splashing. Water at the base of the plant rather than over the leaves.

When to worry

Powdery mildew is common in late summer as the plant nears the end of its cycle. It is only a major concern if it appears early in the spring.

Stopping it coming back

Give your Columbines plenty of space to breathe when planting. Water early in the morning so the leaves have time to dry out completely.

Not sure which one it is? Photograph your columbine.

This page lists the usual causes. Pocket Botanist looks at your actual leaf and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

Get the app

Questions people ask

Should I cut the whole plant back if it has mildew?: If the foliage looks terrible, you can cut it back to the ground. The plant will often send up fresh, healthy leaves in the fall.
Is powdery mildew contagious to other plants?: Yes, it spreads easily through the air. Keep an eye on neighboring plants and improve airflow in the whole garden bed.