Evidence from genealogical and newspaper records proves that the Green family traveled to Utah in 1851. His father Henry, and stepmother, Loiza Spooner, were married in Kanesville, Iowa in April, 1851 and the obituary of Jonathan states that he came to Utah in 1851. Further research is needed to determine the name of the company they traveled with.
There is a "Wilber Green" mentioned in the reminiscence of Jonathan Page, who traveled in the 1852 Outhouse Company. It is possible the date in Wilbur's obituary is wrong and these two Wilburs are the same person. Further research is needed.