Mo Siegel, who founded Celestial Seasonings Inc....

Mo Siegel, who founded Celestial Seasonings Inc. in 1970, will rejoin the Boulder, Colo., company as chairman and chief executive when the herbal tea company buys Siegel’s Earth Wise Inc., the companies announced.

Kraft General Foods acquired Celestial Seasonings in 1984, and Siegel left the company the next year. In 1990, he founded Earth Wise, which makes and distributes biodegradable household detergents and cleaners and recycled trash bags.

Under the merger announced Monday, Siegel will return to Celestial Seasonings, which became independent again in 1988 when it was purchased from Kraft by Celestial’s management and an investment firm, Vestar Capital Partners.