Question
I have been "letting live" anything that will grow under my black walnut tree (day lilies, phlox, iris, blackberry, a woodchuck etc.)  Any chance zebra grass could survive?  I'd like something a little showy, but the surviving plants seem too shaded to give much flower.

Answer
Hi Nancy,
Thanx for your question.  I did not find any references that indicated whether zebra grass would or would not survive underneath a black walnut tree.  There are some plants that do grow okay underneath the black walnut.  The problem is with a chemical called juglone that the tree puts into the soil through its roots, leaves and nuts.  To many plants, this chemical is toxic and intolerable.  To others it is not.  Here is a link to a list of plants that are tolerant of juglone.  I hope this helps.
Tom

http://wihort.uwex.edu/landscape/Juglone.htm