Using black walnut leaves for mulch

Should I use black walnut leaves as mulch?

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**FULL QUESTION** I’ve been reading about the benefits of using leaves as mulch. We have a lot of black walnuts on our property—is it okay to use their leaves as mulch? *—Eileen Fraser, Niagara-on-the-Lake, ON*

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**FULL ANSWER** Do not use the leaves of black walnuts (*Juglans nigra*) for mulch. Like the tree’s roots, bark and nut hulls, they contain a toxin called juglone that can adversely affect other plants. Though the leaves have a lower toxicity level than the ground under the canopy near the roots and where the nuts fall, using them as mulch would still jeopardize other plants. Just take the leaves right out of the garden and find other types to mulch with (midnight raids on your neighbours’ recycling bags are always useful). *—Marjorie Harris, Editor at Large* Other questions recently answered by the GL team: Finding barren strawberry Lilacs that just won't flower Controlling weeds without chemicals Getting rid of pesky iris borers Finding crabgrass seeds Planting under maple trees Discouraging cats from your garden Hints for growing sweet bell peppers Buying exotic plants in Toronto Preventing brown leaf spot Information on peony-flowered poppies Tips for growing tulips and lilies When to move irises Maintaining blue spruces The best way to grow gunneras Getting rid of sawfly larvae on roses Eliminating earwigs from clematis flowers Beetle damage to spruce trees Removing whiteflies from hibiscus leaves Building a cactus garden Maintaining redbud trees Maintaining Boston ivy growth

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