Answer: Unfortunately, rocks placed on top of a barrier fabric or plastic sheeting do tend to collect silt and debris where weeds can then germinate and grow. You could hand weed periodically to try to keep it tidy. I am not sure what size the Delaware Rocks are, but if they are of a size that can be raked then that might help to disturb and thus reduce seedling weeds. I'm sorry there is no easy answer to give you.
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