Bob,

It would probably work better if a vertical were on a mast, but you would
definitely need radials for a decent job.  If you mount it close to the
ground, depending on your soil conditions, you may be able to have decent
performance without radials.  But, any vertical I'm familiar with performs
much better with a few hundred feet of radials.  They can be bent, they can be
different lengths, but generally, the more the merrier.
Steve, K8SP