The wiki says that it will take a seedling 13 hours to get to young. It also says that it takes 29 hours for a young couch potato to get to mature.
There could be a couple of options. I don't know for sure what could be wrong, but here are some possibilities.
You might have not realized that it has only been one day and not two? I don't know lol
Maybe your plant already got to the young stage (which takes 13 hours) and you didn't realize that it still has to go through the young stage to get to mature
This seems like a more logical possibility. Did you place your couch potatoes next to stinkweed? If so, this is most likely the slowness in growth. Stinkweed slows their aging process by 25%.
Maybe you're not checking them on a regular basis? If you wait two days to check, they won't mature as fast. I check my plants once a day (some check theirs every few hours). My plants won't mature as fast, because I'm not using the baby-mature-elder timing cycle.
Do you have some or all the likes for the Couch Potatoes? Be sure to look up in the Wiki for likes and dislikes.
Plants only advance to the next level when you log into the game on that character who has the garden.
