A. Growing anything under a walnut is a problem as the tree emits a growth inhibitor called juglone. Another problem would be the dry condition due to root competition and the shade. None of these are conducive to growing a rose. My best suggestion would be to try a large pot with a rose planted to give max sun. Any rose from miniature to any of the teas, etc. would be suitable. In the Fall, remove the rose or roses and bury in the vegetable garden so they are protected from winter frost.

Master Gardeners of Ontario