MONROE — The Monroe-based Sisters, Servants of the Immaculate Heart of Mary have sold 120 acres of land to locally based furniture maker La-Z-Boy Inc. for the company’s new global headquarters.

The sale, the price of which was not disclosed, was finalized Jan. 25. The company plans to build a new $50 million headquarters complex on the Downriver site that will house 500 employees by late 2014 or early 2015.

The 120 acres, partly in Monroe and partly in Frenchtown Township near Telegraph and M-50, is remarkable for its environmental beauty, featuring many tall oaks and a meadow, and has been maintained by the IHM sisters for decades as a nature preserve. Part of the sisters’ mission includes environmental conservation, so La-Z-Boy’s pledge to keep the land as undisturbed as possible was a “very significant” factor in the order’s decision to sell, said Sr. Sue Sattler, IHM, who also has been a lawyer since 1976.

“La-Z-Boy agreed to preserve a remnant oak savannah, an endangered ecosystem on our campus,” Sr. Sattler said. “This is consistent with IHM’s commitment to preserving green space within Monroe,” adding that the company said it had no plans to develop the land beyond the spaces needed for the headquarters building, parking areas and similar needs.

She said La-Z-Boy also is committed to achieving LEED certification for its headquarters and has proven in its manufacturing processes that it aims to achieve sustainability, energy and resource efficiency.

Sr. Sattler also said the IHMs’ mission for the site included transforming the campus into a “learning laboratory for sustainable living,” something in which La-Z-Boy has shown willingness to cooperate. The order still maintains about 120 acres at the site for its own use.

“Over the past 12 years we have made concrete decisions to turn this vision into a reality,” Sr. Sattler said. “Among many other activities, we have hosted over 10,000 visitors of all ages to tour the Green House,” including students from nearby major universities.

“This partnership with La-Z-Boy offers IHM a unique opportunity to work with a for-profit company in which sustainability is part of their core culture,” she added.

The IHMs have received many offers over the years for the site. In contrast, La-Z-Boy had entertained many offers to relocate elsewhere — including to other states — before settling on the deal with the IHMs to remain in Monroe. Since civic involvement is part of the sisters’ mission, saving 500 local jobs was also a significant factor, Sr. Sattler said. And the proceeds for the sale will help the sisters care for its membership as well as reduce maintenance costs for the site, she said.