Hothouse (Torchwood Hub)
The Hothouse was a greenhouse room in the Torchwood Three Hub. It was used for storing alien plants, and plants from different geological eras, which had travelled to early-21st century Cardiff through the Rift. This project was largely overseen by Owen Harper.
In 2008, Ianto Jones fell victim to a telepathic, parasitic alien plant, which he was tended to diligently. He spent two whole days in the Hothouse, barely eating, sleeping or shaving. He also moved all other plant specimens out onto the spiral staircase leading up to the hothouse to give the parasitic plant more space. When Jack Harkness found Ianto feeding the plant his own blood he destroyed it. (PROSE: Plant Life)
During a zombie outbreak in 2009, after finding Trystan Thomas savagely attacked, Ianto made up a bed for him in the Hothouse, reasoning that it would be "nice and quiet in there". (PROSE: Bay of the Dead)
Also in 2009, but presumably after Trystan Thomas had stayed there, the hothouse housed a man-eating plant. (PROSE: Consequences)