The Tenochcas who settled late in the Mexica Valley soon found land was at a premium there, and devised an ingenious system of creating "floating islands" in order to overcome the problem of land shortage. These chinampas, or “floating gardens”, increased the land area available for cultivation and served as settlement extensions for lakeside cities. Tenochtitlan would never have attained its estimated population of 250,000 on its original small island, and numerous other cities expanded in the same fashion.

Chinampas were remarkably productive tracts of land build up in the shallow beds of freshwater lakes, were constructed from alternate layers of mud and vegetation which were secured by posts and the roots of willow trees. Plots were systematically planned and arranged in the lake, and each was typically bordered on one side by a canal and on the other by a footpath adjacent to another field. Fertility was enhanced by intensive cultivation techniques: fresh mud was always added before planting to maintain fertility of the earth, and water for irrigation was supplied by dipping into adjacent canals, a process which also dredged the canals and kept them clear for canoe transport. Cultivation was accomplished by the effective use of seedbeds, thus allowing for continuous planting and harvesting of crops.

The chinampas ranged in size from 100-850 sq.metres and were cultivated by an average of 10-15 people each. They probably weren’t capable of producing a substantial surplus for sale to the urban population, so maybe their value lay in their ability to produce high yields of garden vegetables and aromatic flowers.

The best place to see what remains of the former canal and chinampa system of Aztec Tenochtitlan today is Xochimilco ("Place where Flowers Grow"), a suburb in the south of Mexico City, where even today flowers and fruit are cultivated along a series of winding canals.

The image below shows a chinampa district, probably located on outskirts of north-western Tenochititlan (detail of a copy of Plano en papel de maguey c. 1523-5)