Abstract: A smart city is a city capable of adjusting its sizes, structures and shapes. Nature gives us the information how this could be achieved. The 'Software' of the city (green, water, food, sustainability, social constructs) is obstructed by the 'Hardware' (infrastructure, roads, sewage, buildings, economics). This makes it hard to create space for Climate Impacts and Urban Agriculture as their requirements are uncertain, temporary, change seasonally, occur suddenly and change over longer periods and street patterns, main structures and buildings are usually immovable. This hardware dominance often leads to a downturn also (Detroit, Chicago, Eastern Germany, Liverpool, e.a.). Thus, becoming smart by nature, eg let the rules of nature guide us in city planning, could improve the adjustability of the city and allow spaces to shrink and grow, depending the needs at times. Nature's principles function as ultimate smart design principles. For the city, as a complex adaptive system lessons can be learnt from Swarm behaviour. The reason to develop the Swarm Planning concept, able to develop smart city designs adjustable to uncertain future claims, helping to create flexible spaces with more room when required for the software of the city: Smart Green Urbanism. The paper will describe, compare and discuss six case studies in which the Swarm Planning concept is applied to provide more space and flexibility for climate impacts and urban agriculture. The way nodes and networks, determine the way unplanned (often unused) spaces are occupied), structures and systems are formed, hubs, exchange and intense connections lead to emergent occupation patterns, provide the space to accommodate climate impacts and the growth of food and impact on the city designs. The findings of these six studies are subsequently used to develop an autarkic design for a climate proof, fish-based food system in the Netherlands