Spontaneous plants are a new kind of wilderness that thrives in cities. They are able to grow in the harshest conditions without being planted or cared for. Plants in cities require more water, have less access to nutrients, and are more vulnerable to diseases. Choosing the most resilient plants, regardless of origin, is essential for cities' capacity to adapt. Spontaneous plants give us an opportunity to create landscapes that are ecologically beneficial at a low cost and with minimal maintenance. This thesis creates a framework to allow nature to establish its own communities and build resiliency in the face of climate change and increasing urban degradation.