Becky, sorry I didn't get to this sooner. I've been pulled away from the computer a good bit over the last few weeks.
I've never grown in a soil with nematodes, but I know all too well about the need to grow in raised beds. Do the nematodes stay lower in the ground, or do they completely fill your raised beds as well? (I'm completely unfamiliar with their habits.) I have many pots that contain both a rose and a clematis, and in a few cases, they have three plants all together. However, with these, they are huge pots and have the bottoms cut out of them so that the roots can continue into the ground once they run out of room in the pot. Would the nematodes come up into the pot if you used this strategy? I think you would find that eventually your plants would start finding their own way out of the pot (via the drainage holes, and possibly crack your pots, if you didn't pre-cut the bottom for them.
