From Henry Hardin of California, by Fredna Tweedt Irvine (Belmont, MA: 1976), page 78:

Jeff was in charge of the distillery on the home plantation, but he was given land when he married.

Appears to have come to California before the group which is believed to have come out with the Hagans-Cockrill 1853 immigration. From a biography of his son, Laban Andrew Hardin, An illustrated history of Sonoma County, California (The Lewis Publishing Company, Chicago: 1889), page 669:

In 1852, Mr. Hardin, with his wife and three children, emigrated to California. Leaving Missouri on the first day of May, they made the trip overland, and after a journey of six months, landed in Sonoma County. The first year he lived on the Laguna Creek, near Sebastopol, and from there moved into Vallejo Township and, in the fall of 1855, to Ketcheside ranch in the hills.... In the fall of 1856 he bought the Hardin property direct from General Vallejo. It then consisted of 400 acres, and the following rear he purchased from the same party 200 acres more. Mr. Hardin made this his home until 1877....

After this time he lived in Santa Rosa, Petaluma and Cloverdale.

From the San Jose Pioneer, Aug 1900 (copy from Kit Fuller):

WILLIAM J. HARDIN, the well known pioneer, died at his home in Petaluma, where the family has lived since moving down from Cloverdale last month. He passed away after a lingering illness extending over a period of five years. After his removal to Petaluma he seemed to rally somewhat but this seeming improvement did not last long and he grew gradually weaker.

The deceased was born in Kentucky seventy-nine years ago. He came to this state in 1852. He owned considerable property in Mendocino county, and when he moved to Petaluma many years ago he lived on what is known as the Ormsby place. He was very highly respected.