Black Walnut Toxicity: Why Camellias Fail Under Juglone

The Culprit: Juglone

Black walnut (Juglans nigra) roots release juglone, a chemical toxic to many plants. It inhibits respiration, causing wilting, yellowing, and death.

Camellia Sensitivity

While not on every published list, camellias are highly likely sensitive. Azaleas (related ericaceous plants) are confirmed sensitive. Your observation—camellias die, azaleas partially survive with extra water—matches juglone toxicity exacerbated by drought (juglone concentrates in dry soil).

What Works Near Black Walnut

Very few ornamentals tolerate juglone. Resistant options include:

• Japanese maple, redbud, dogwood, hosta, ferns, astilbe, Virginia bluebells.
• Grasses and many native woodland perennials.

Management Strategies

• Remove the walnut if possible (juglone persists in roots for years after removal).
• Plant in raised beds with imported soil and a root barrier (heavy plastic) at the base.
• Keep soil consistently moist—juglone mobility increases in dry conditions.
• Compost walnut leaves separately—do not use in garden beds.

Bottom Line

Your camellia failures are almost certainly due to juglone. Relocate them well beyond the walnut's dripline (roots extend 1.5× canopy width) or use raised beds with barriers.