Construction of a $11.5 million retail shopping complex has been started on an undeveloped 10-acre Rockville Pike site that formerly was part of the Dawson farm.

Called Wintergreen Plaza, the two-story complex will have 145,000 square feet of commercial space for 60 stores at Edmonston Drive and the Pike. The site is a quarter mile north of Woodmont Country Club and near the older Congressional Mall. The three-year-old White Flint Mall remains the largest commercial development on the Pike.

Lowell E. Baiser and Robert E. Sokolsky are principls in the Rockville Pike Joint Venture Limited Partnership tht is developing the new shopping plaza, which Baiser said will be anchored by a Grand Union food store.

Walker & Dunlop and DRG Financial of Washington arranged construction and permanent financing for Wintergreen. The permanent loan was placed with First National Bank of Maryland.

Architect Morton W. Noble designed the plaza to have domed circualr entrances and elevator service. Fordham Development Co. is the leasing agent and the general contractor is Glen Construction Co. DMW Consultants is the landscape architect.

Baier said that Wintergreen Plaza, which s expected to be ready for occupancy next spring, will be built on the last large tract to be developed on Rockville Pike, which now is heavily populated by business and shops north of Strathmore Lane in upper Bethesda all the way to Rockville.