Hechinger Co., the rapidly expanding retail home center chain, revealed yesterday that it plans to construct a large new store in a retail complex adjacent to Montgomery Mall.

Included in the project will be a 60,000-square-foot Hechinger's branch, a 20,000-square-foot garden center, another larger retailer and more than 30,000 square feet of smaller stores. The new retail center will add to the already powerful magnet of Montgomery Mall for the relatively affluent shoppers in the area.

In addition, the new location meets a chief goal of Hechinger management in recent years: To tap the large market-place between its big, modern Rockville store and a smaller, old unit on Wisconsin Avenue in Northwest Washington that carries a limited amount of merchandise.

The plans for a new Montgomery County store were revealed by the company's officers at the annual meeting of Hechinger stockholders yesterday.

In addition, Chairman Richard England and President John Hechinger noted that workers will begin installing the roof in a few days on the company's store under construction in Northeast D.C. at the intersection of Maryland Avenue and Bladensburg Road. The store will open later this year.

Located on the site of a former Hechinger store and the firm's old headquarters, the new home center (also 60,000 square feet plus a garden center as large as planned for Montgomery county) will be part of an inner-city mall that the Landover-based firm is developing to include the largest Safeway food store in the United States and some 40 smaller retail or service outlets in one of the most underserviced concentrations of population in the metropolitan area.

Both the new Montgomery County and D.C. stores will serve markets of about 300,000 potential customers, the Hechinger officials said.

In addition to new Washington area units, Hechinger Co. also has staked out a broader Maryland-Virginia marketplace for future growth.

In other developments, stockholders approved an increase in authorized common shares to 10 million from 5 million and the re-elections of seven directors.