How can weeds help us understand Istanbul’s urban transformation in a different way? Over the past two decades, Istanbul’s population has grown from roughly 8.7 million in 2000 to 15 million in 2020. Alongside that demographic growth, new infrastructure projects have also made possible a staggering expansion of the city’s urban footprint. While the causes of this social and spatial expansion are complex, a core mechanism for Istanbul’s transformation has been property. Measuring, mapping, buying, selling, and developing property has become key not only to the politics of the Justice and Development Party but a broader social imaginary. From one point of view, property’s ascendance signals a city made legible and transparent to the needs of an urban market. Yet there are places in Istanbul where that regime of property breaks down. This paper introduces the analytic of ‘weedy property’ to make visible some of those sites. Following the growth of the ‘tree of heaven’ (kokar ağaç, ailanthus altissima), this paper asks where, how, and why this quintessential urban tree - often described as an invasive weed - grows where it does. I highlight three kinds of places where the tree of heaven is especially prevalent: the margins of registered vakıf (waqf) property, old gecekondu neighborhoods, and properties embroiled in inheritance struggles. Thinking in terms of weedy property thus helps us to understand property not merely as an object to be bought and sold but as a relation that links people, places, and temporalities together in unexpected and uneven ways.