Can I save a leaf that has yellow patches?

No, once a leaf is infected with downy mildew, it will not turn green again. It is best to prune it off to protect the rest of the plant.

Does yellowing mean I need fertilizer?

Usually not. Yellowing is rarely a sign of nutrient deficiency in this species, so check for moisture or disease first.

Western wallflower: yellow leaves, causes and fixes

Check these first

Inspect the underside of yellow leaves for fuzzy growth.
Stick your finger 3 inches into the soil to check for dampness.
Clear away debris from around the base of the plant.

Likely causes

Downy mildew
Most likely
How to tell: You will see yellow patches on the leaves, often accompanied by a fuzzy growth on the underside during humid weather.
What to do: Remove the affected leaves immediately to stop the spread. Improve air circulation around the plant by thinning out nearby vegetation and avoid overhead watering.
Overwatering
Possible
How to tell: The leaves turn yellow and feel soft or mushy to the touch. The soil stays wet for more than 14 days.
What to do: Let the top 3 inches of soil dry out completely before watering again. Ensure your planting site has excellent drainage and is not sitting in a low spot.

Yellow leaves on other plants

Find out what's wrong with your western wallflower

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

When to worry

Worry if the yellowing spreads rapidly across the whole plant. It is normal for the very oldest bottom leaves to yellow and drop as the plant matures.

Stopping it coming back

Plant in full sun with plenty of space between plants to ensure good airflow.

Western wallflower: yellow leaves? Check yours with a photo

Every plant is a little different. Take a photo of your western wallflower and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

Get the app · Or check it from a photo now, free

Questions people ask

Can I save a leaf that has yellow patches?: No, once a leaf is infected with downy mildew, it will not turn green again. It is best to prune it off to protect the rest of the plant.
Does yellowing mean I need fertilizer?: Usually not. Yellowing is rarely a sign of nutrient deficiency in this species, so check for moisture or disease first.

Guides to these causes

Downy Mildew

Why are my Western wallflower leaves turning yellow?

Check these first

Not sure what's wrong with your western wallflower?