Plants alone arn't really worth streaming, maybe just have a system that takes a picture and updates it every 5 minutes or something. Now add some critters in there and it might possibly get some views.
I've thought of doing a north sky stream, basically have a tethered DSLR that takes long exposure (or just set to auto) pictures of the north sky and then streams it. It would basically be a streaming slide show. Occasionally you'd get northern lights and stuff show up. If ever I decide to put up a ham radio tower I might experiment with that. Need a mirrorless DSLR for that though otherwise you'll kill the shutter/mirror. Mirrorless DSLRs arn't cheap.
A web cam for an aquarium could be fun too. They have aquarium TV channels, but it just keeps repeating the same thing, an actual web cam showing an actual aquarium could be fun. The trick with anything like this is to make it reliable though. So many people setup streams like this and half the time they're down. Heck even NASA can't keep the ISS stream going 24/7, they need to install more Earth repeater stations.

I imagine this is not something they wanted to spend much money on, it's just a fun thing to have.