When does Bonanza return?

Bonanza is an American Western television series that ran on NBC from September 13, 1959, to January 16, 1973. The show is set in the 1860s and centers on the wealthy Cartwright family, who live in the vicinity of Virginia City, Nevada, bordering Lake Tahoe. The title "Bonanza" is a term used by miners in regard to a large vein or deposit of silver ore, from Spanish bonanza (prosperity) In 2002, Bonanza was ranked No. 43 on TV Guide's 50 Greatest TV Shows of All Time.
The show chronicles the weekly adventures of the Cartwright family, headed by the thrice-widowed patriarch Ben Cartwright (Lorne Greene) The family lived on a thousand square-mile (2,600 km2) ranch called the Ponderosa on the eastern shore of Lake Tahoe in Nevada opposite California on the edge of the Sierra Nevada range. Each wife was accorded a different ancestry: English (S02:E65 – "Elizabeth My Love"), Swedish (S03:E95 – "Inger My Love), French Creole (S04:E120 – "Marie My Love") respectively.