Answer: Depending upon the type of shrubs you're removing, an application of the herbicide Round-Up shouldn't be necessary. (There are some plants with especially problematic roots, but these are exceptions). Physically digging up and removing most of the roots should be enough to discourage any growth from the remaining roots. I'd dig the shrubs out, rototill (and handpick any sizable remnants of roots), then add topsoil and some organic matter to the bed. The bed should be ready to plant immediately.
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