Can I use a growing tent as a dark room?

Well, if it is indeed light tight, then you are golden. But may be unecessary unless you plan to 'print' in there as well, and part of the printing process would REALLYbe helped by running water, and a sink.

There are two times you need low light, the first one mentioned involves a process in which it is crucial that you are in complete darkness.China wholesale grow tent
a) Removing the film from your camera, taking in from the cannister and loading it into the film developing cannister. (I simply use to use a closet, packed with hanging clothes, and do the deed. I'd put a towel down on the floor on the inside. No issues.; after the film tank is loaded, than no worries regarding light, and I would do my film development in a well lit kitchen.
b) The Print making process. Your negatives have been developed, hung and dried.
Now you need an enlarger, three trays a little larger than your largest print, but one of them as large as space can accomodate. Uber light tight in this situation? Mehh. Not really. Just don't let light get on your print paper when you pull it from it's envelope, place it on the enlarger easel, and put it face down subsquently when developing.
If you have a small room (bathroom) that can easily made light tight, then you can feed one of your trays with running water (the last and largest tray) to 'wash' your prints before drying. (Oh, and don't forget a red light, and a timer.)