Planting under walnut trees - Knowledgebase Question

Farmington, Mi
Question by carlautter
April 24, 2010
Have 4 large black walnut trees with flower garden very nearby. Last several years I,ve planted impatiens along with the ferns and hosta but last year the impatiens did poorly. What do you recommend I plant and also how should I amend the soil. Thank You!

Answer from NGA
April 24, 2010


Juglone is the chemical exuded by the roots, bark, and leaves of walnut trees. Some plants are more susceptible to the growth inhibiting toxin and will not grow directly beneath the canopy of walnut trees. Interestingly, impatiens are on the list of juglone tolerant plants so there may have been something else going on with your impatiens last year. Annuals with the most tolerance to juglone include Begonia; fibrous cultivars and the tuberous cultivar 'Nonstop', Calendula, Impatiens, Ipomoea 'Heavenly Blue' Morning glory, Viola cornuta, Viola tricolor,
Viola wittrockiana, and Zinnia. Before planting this spring, amend the planting area with compost and dig it in to a depth of about 8 inches. Best wishes with your annuals!

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