Around the suburbs of Kansas City, there's no shortage of housing developments where you can buy an empty lot and are expected to use the land to build a house.
Would there be any zoning law preventing me from buying such an empty lot and turning it into a giant garden or a private park? Not a commercial farm, but a private thing.
Zoning is controlled by the municipality (and possibly state, given where KC is) so you would have to check the rules for the municipality of interest and look at the specific zoning designation (e.g. RP-OE, R-2, MXD). Here for example is a page of code from Overland Park, which tells you that RP-4 land can be used for a private park, but agriculture is not a listed permitted use. You might argue with city hall over whether a giant garden is agriculture, and you might even win the argument (if it is a garden where you don't harvest product). Private / non-commercial is not likely to be the controlling factor over agricultural use.
It's not just an expectation to build a house, the plots may have deed restrictions which mandate it. Especially in a housing development, deed restrictions are common to make sure owners are building homes to match the neighborhood. Likely restrictions would include breaking ground on a house (of an approved design) within 12 to 24 months of purchase of the lot.
