Acid tolerant plants
What flowering plants will grow well in full shade under English walnut trees. I now have lilies of the valley and an azalea shrub. The lilies are propagating slowly and the azalea does not bloom as well as those in the sun. The flower bed they are in is about six feet deep and sixty feet wide so there is a lot of room for additional plants.
Yamhill County Oregon
Thank you for your question. Walnut trees (Juglans ssp.) have a chemical (juglone) that keeps many plants from growing and/or thriving if located near them. In addition, their shade is too deep for many flowering plants. Here is a list of plants that can grow near walnut trees: https://extension.psu.edu/landscaping-and-gardening-around-walnuts-and-other-juglone-producing-plants Azalea is an understory plant (shade) not listed as being tolerant, so it may be doing poorly due to the juglone. I hope this is helpful.