Can I just use regular fertilizer to fix the yellowing?

No, regular fertilizer might make it worse if the pH is wrong. You must fix the acidity first so the plant can actually use the nutrients.

Will these leaves turn green again?

Usually not. Once a leaf has turned yellow from chlorosis, it will likely stay that way, but new growth should come in healthy once the pH is corrected.

Rhododendron: yellow leaves, causes and fixes

Check these first

Check the soil pH with a home testing kit.
Inspect the undersides of the leaves for tiny insects.
Look for green veins against yellow leaf tissue.

Likely causes

Chlorosis
Most likely
How to tell: The leaf veins stay green while the rest of the leaf turns a pale yellow color. This happens when the soil pH is too high for the plant to absorb iron.
What to do: Test your soil pH and aim for a range of 4.5 to 5.5. Apply sulfur to lower the pH levels around the root zone, and use an iron chelate supplement to correct the iron shortage in the meantime.
Lace bugs
Possible
How to tell: You will see tiny yellow or white stippled spots on the top of the leaves. Check the undersides for small black spots of excrement and the insects themselves.
What to do: Spray the undersides of the leaves with insecticidal soap or neem oil. Repeat the application every 7 to 10 days until the bugs are gone.

Yellow leaves on other plants

Find out what's wrong with your rhododendron

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

If the yellowing spreads rapidly across the whole shrub, it is time to act. A few yellow leaves deep inside the plant are normal as they age and drop off.

Stopping it coming back

Keep your soil acidic by adding pine needles or peat moss to the mulch around the base of the plant.

Rhododendron: yellow leaves? Check yours with a photo

Every plant is a little different. Take a photo of your rhododendron 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 just use regular fertilizer to fix the yellowing?: No, regular fertilizer might make it worse if the pH is wrong. You must fix the acidity first so the plant can actually use the nutrients.
Will these leaves turn green again?: Usually not. Once a leaf has turned yellow from chlorosis, it will likely stay that way, but new growth should come in healthy once the pH is corrected.

Guides to these causes

Chlorosis

Why are my rhododendron leaves turning yellow?