The city of vienna is working on a general concept for urban development goals, to be reached by 2020. Within this context an open competition was launched, aimed at finding and developing ‘urban oases’. The winning projects are the ‘bimbaum’ and the ‘flowerflash’ by xarchitekten + henning grahn. The projects offer new strategies for temporary and flexible plantation in addition to conventional greening. they activate urban sites which are not adequate for permanent vegetation.