The invention relates to a horticultural and/or agricultural greenhouse for cultivating crops therein, comprising: multiple rows of support legs connected by transverse frames for forming a roof support construction； 5 a substantially horizontal fabric screen for at least partially darkening and/or thermally shielding the greenhouse, wherein the fabric screen is suspended between adjacent transverse frames and divides the greenhouse in a cultivating space and a roof space； and a ventilation 10 system with a ventilation device for displacing air within the cultivation space and/or between the roof space and the cultivation space, and a ventilation device adapter configured. for receiving the ventilation device and for being secured to one of the transverse frames, the 15 respective transverse frame having a frame length and the ventilation device adapter extending over substantially the frame length, wherein the ventilation device adapter is provided. between. the respective transverse frame and. the fabric screen.
