Mass. Gen. Laws ch. 40A § 4
No zoning ordinance or by-law shall regulate or restrict the use of materials, or methods of construction of structures regulated by the state building code, nor shall any such ordinance or by-law prohibit, unreasonably regulate, or require a special permit for the use of land for the primary purpose of commercial agriculture, aquaculture, silviculture, horticulture, floriculture or viticulture, nor prohibit, unreasonably regulate or require a special permit for the use, expansion, reconstruction or construction of structures thereon for the primary purpose of commercial agriculture, aquaculture, silviculture, horticulture, floriculture or viticulture, including those facilities for the sale of produce, wine and dairy products, provided that either during the months of June, July, August and September of every year or during the harvest season of the primary crop raised on land of the owner or lessee, 25 per cent of such products for sale, based on either gross sales dollars or volume, have been produced by the owner or lessee of the land on which the facility is located, or at least 25 per cent of such products for sale, based on either gross annual sales or annual volume, have been produced by the owner or lessee of the land on which the facility is located, and at least an additional 50 per cent of such products for sale, based upon either gross annual sales or annual volume, have been produced in Massachusetts on land, other than that on which the facility is located, used for the primary purpose of commercial agriculture, aquaculture, silviculture, horticulture, floriculture or viticulture, whether by the owner or lessee of the land on which the facility is located or by another, except that all such activities may be limited to parcels of 5 acres or more in area not zoned for agriculture, aquaculture, silviculture, horticulture, floriculture or viticulture. For such purposes, land divided by a public or private way or a waterway shall be construed as 1 parcel. No zoning ordinance or bylaw shall exempt land or structures from flood plain or wetlands regulations established pursuant to general law. For the purposes of this section, the term agriculture shall be as defined in section 1A of chapter 128, and the term horticulture shall include the growing and keeping of nursery stock and the sale thereof. Said nursery stock shall be considered to be produced by the owner or lessee of the land if it is nourished, maintained and managed while on the premises.
Districts shall be shown on a zoning map in a manner sufficient for identification. Such maps shall be part of zoning ordinances or by-laws. Assessors' or property plans may be used as the basis for zoning maps. If more than four sheets or plates are used for a zoning map, an index map showing districts in outline shall be part of the zoning map and of the zoning ordinance or by-law.
Mass. Gen. Laws ch. 40A, § 4