Black walnut is one of the most common large shade trees on older Richmond, KY lots, and one of the most common calls we get is a homeowner asking why their tomatoes, peonies, or azaleas keep dying under one.
Do Black Walnut Trees Poison Nearby Plants?
Yes, for sensitive species — black walnut roots release a compound called juglone that stunts or kills tomatoes, peppers, and several ornamentals growing within the tree’s root zone.
Juglone occurs in the buds, hulls, and roots of every part of the tree, and the effect is strongest within the dripline, though Purdue Extension notes the toxic zone can extend well beyond it as roots spread wider than the canopy. Tomatoes, peppers, eggplant, and plants like lilac, peony, and azalea are among the most sensitive. Other species — corn, most grasses, cherry, redbud — tolerate it fine, which is why a lawn under a walnut is usually unaffected while a vegetable bed a few feet away struggles.
Should You Remove a Black Walnut Because of Juglone?
Usually not for juglone alone — moving or raising sensitive plants outside the root zone is cheaper than removing a healthy shade tree, unless the tree has its own structural or health problems.
For a vegetable garden, the practical fix is planting sensitive crops in raised beds or containers, or simply moving them beyond where the walnut’s roots reach — not cutting the tree down. Where removal does make sense is when the walnut itself is declining, storm-damaged, or growing too close to a foundation, not because of juglone by itself. A mature black walnut removal in Richmond typically runs the same $1,000–$3,000+ typical range as other large trees, depending on size and access. If you’re not sure whether a walnut’s decline is juglone-related soil stress or something else, our tree disease and pest diagnosis visit sorts that out before you spend on either a removal or a garden overhaul.
Common Questions
How far from a black walnut is safe to garden?
Sensitive plants are usually safest well outside the dripline, though exact distance varies with soil and drainage — raised beds are a more reliable fix than trying to measure a safe radius.
Is grass safe to grow under a black walnut?
Yes, most turf grasses tolerate juglone well. Lawns are typically one of the least affected things you can grow under a walnut.
Does composting walnut leaves spread juglone to other beds?
Juglone breaks down over time in a properly maintained compost pile, but many gardeners keep walnut leaves and hulls separate from beds meant for sensitive vegetables to be safe.
Related: tree disease & pest diagnosis · tree removal cost by size · arborist assessment. Back to Richmond Tree Pros.
Richmond Tree Pros · Serving Richmond, Berea, Winchester, Mount Sterling & Madison County, KY · Call or text (859) 310-1209
Last updated: September 3, 2026