When the Aztec people finally found a place to settle down, they did so on rather marshy land around a lake. Some of the land was not very good for gardening. As the population grew, the Aztecs needed to find a way to grow more food. They could have built further away from the cities, but then they would need to guard the fields from robbers.
Instead, the clever Aztec engineers created “floating” gardens. The floating gardens were actually rafts. The rafts were anchored to the bottom of the lake, or to a strong tree in the marsh. They piled vegetation and reeds on top of the raft to help provide good soil and drainage. On top of this, they piled dirt. They planted seeds in the dirt. The gardens were used to grow chili peppers, corn, tomatoes, beans, and squash.
It was somewhat difficult to harvest the food since the gardens were floating in marsh water. To solve this, Aztec engineers built mud and stone walls around each floating garden. The walls acted as walkways between the gardens.
The floating gardens solved some of their problem, but as their population grew, they needed more land. Their engineers solved this by designing dikes to hold back water. They filled in the marshlands and swamps just as they had the rafts, the floating gardens.