Maryland Code, Local Government § 4-509

(a) Unless the zoning classification is amended under the procedures required by the county, for 5 years after the effective date of the unified charter, the land of a merging municipality that does not have planning and zoning powers may not be placed in a zoning classification that allows a land use substantially different from the use allowed by the master plan or plan of the county or agency that has planning and zoning jurisdiction over the land before the merger.

(b) This subtitle does not grant planning and zoning powers to a unified municipality if none of the merging municipalities has planning and zoning powers.