Well, there is a row of small, north facing windows, but they don't provide enough light to be worthwhile to plant growth. I also bring some cactus in there over winter. As long as the plants are kept cool, they are fine. The problem is if they are warm and actively growing in dim light, then they will quickly grow spindly and exhaust themselves. However, during dormancy you can keep them in total darkness, if you wish. Some people even put their plants in a refrigerator for dormancy. In any case, the plants grow, increase and flower every year. Look in on them occasionally to make sure they dont' dry out too much, and occasionally trim off leaves that have completely turned brown. I usually trim all the leaves back before they go outside again in Spring.
Note, your father's plants outside may not be doing well, by his pond, due to too much nutrients in the soil and/or provided by the pond water (esp. it there is fish in the pond)