I found HORTUS to be a fascinating project. I liked that the interactivity of the project was quite crucial to the success of the project. I would enjoy visiting that installation; it seemed well-designed throughout. It sparked thoughts of what the effects of the immense volume of CO2 exhaled in England actually does to the bacteria living in the city, on a large scale. It was also quite poignant and timely for them to incite thoughts of biologically generated usable energy, but perhaps too little too late.
I didn't quite get the virtual garden part. I looked through it, and it seemed to be just a list of the microorganisms in the project, rather than a matrix of real-time images or representations of the organisms, which I expected.