Walking iris not growing
I was given a dozen or so walking iris plants a few years back, and they are not really doing much. They have not bloomed since I planted them. They are mostly still green, but a few are starting to show yellowing in the leaves. They are planted in a raised bed that surrounds two oak trees. I can't seem to locate a lot of information related to what might be wrong with the growing conditions or how I can help them flourish. Any help appreciated. Thanks!