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Black Walnut · Juglans nigra

Why are my black walnut leaves turning yellow?

It is less common for a healthy black walnut to have yellow leaves, so this usually points to a nutrient deficiency or poor drainage. Check the soil moisture and the color of the veins first.

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yellow leaves on a plant
Photo: Trio3D, CC BY-SA 4.0

Check these first

  1. Check the soil moisture level with your finger.
  2. Inspect the leaf veins to see if they are still green.
  3. Test the soil pH level.

Likely causes

  1. Iron Chlorosis

    Possible

    How to tell: The leaves turn yellow while the veins remain green. This happens when the soil pH is too high for the tree to absorb iron.

    What to do: Test your soil pH and aim for a range of 6.0 to 7.0. Apply a chelated iron supplement to the soil if the pH is above 7.0.

  2. Overwatering

    Possible

    How to tell: Leaves turn yellow and may feel soft or limp. The soil stays wet for more than 14 days after watering.

    What to do: Check the soil depth for saturation. Allow the top 3 to 4 inches of soil to dry out completely before watering again.

Yellow leaves on other plants

Find out what's wrong with your black walnut

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.

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When to worry

Worry if the yellowing spreads rapidly across the entire canopy. It is normal for a few inner leaves to yellow and drop in late summer as the tree prepares for autumn.

Stopping it coming back

Maintain consistent watering every 7 to 14 days and ensure the planting site has excellent drainage.

Black Walnut: yellow leaves? Check yours with a photo

Every plant is a little different. Take a photo of your black walnut 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.

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Questions people ask

Will yellow leaves turn green again?
Usually no. Once a leaf has turned yellow due to chlorosis or damage, it will not recover its green color.
Does my tree need fertilizer?
Only if a soil test confirms a nutrient deficiency. Over fertilizing can actually stress a black walnut.

Guides to these causes

More problems with Black Walnut

Back to the Black Walnut guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.