Well I still haven't told her and don't plan on doing it soon, but I almost got caught last night.
She was not suppose to be coming over for another hour or so but showed up early. I was rushing around like crazy trying to get things watered last night so I didn't lose my crop. Most of my plants can be watered in the room and drain into a res. But I have 6 plants in my vert setup that are not on shelves so they have to go into the bath tub to get watered. I had 3 of the six in the bath tub and was watering them. Then I hear the door bell.
I freaked out and started sprinting around trying to get the plants back in the cab, the door closed, etc. I was all sweaty when she showed up and I was almost shaking I was so nervous. Luckily I was hungry and she offered to go get me food while I took a shower. When she left I was able to finish my watering and close my cab correctly. I thought I was going to have to tell her long before I planned on it. Luckily she was nice and went and got me food.
I am just glad I didn't have all 6 plants in the tub. I had to put my plants back in the cab still leaking water everywhere, but it was well worth the mess to not have my plants out when she showed up.