In reality, predominant wind directions are of little meaning in such situations. All it takes is one good day of S.E. wind, not weeks and weeks of it, to propel such material hither and yon. But very basically, one in the N. hemisphere can expect SE winds to occur ahead of cold fronts and low pressure systems, on the "front side", so to speak. Air tries to rush into a low pressure center but because of the earth's spin, it ends up circling around in a vortex. One can literally follow a storm system's progress and location simply by noting wind direction and changes in same. +oM

You can find several lists on Google of plants that are tolerant or susceptible to juglone. Is the area dry since it's on a berm? Redbud might do well there. Here is a link that might be useful: Google - Juglone tolerant plants

Thanks all for your thoughts! Yes, this is the only place I can plant. It is a typically smallish downtown Toronto yard, with several trees shading the (Eastern) 2/3 of it. That leaves the back (Western) 1/3 open for planting. I've actually decided to do fewer beds because I have become less optimistic about my sunlight situation (and my budget for buying soil). The research I've done suggests that the highest concentration of Juglone is in the roots of the tree, and if I can keep the roots from coming in contact with the soil around my sensitive plants (as well as keeping the beds away from the dripline and clearing them of any Walnut tree debris), I am hoping that even the sensitive plants should be ok. The whole yard is pretty dense with tree roots (maple, cedar...) which could also creep into my beds and, while not poisoning my plants, they could crowd their roots and feed on their nutrients. I've been told that as I water my garden, the tree roots are likely to rise towards the surface of the yard where the moisture is, rather that growing down. I hope I don't sound too paranoid, but I figure I should try to do this right the first time.

sound like you might have 'black runner', a taro which spreads by fairly thin rhizomes that you might not notice. Good luck and good news if it's hardy in zone 6. I have some black runner plants to trade if anyone is interested.