Indoor Gardening!
Everybody else probably already knows this, but I just realized that our sims can garden indoors! It's winter in my game, so I was getting frustrated by a sim who wants to improve her gardening skills...
Forum Discussion
From what I know, plants will progress something like 5x as slow when they're sheltered. So essentially, it's best to put them outdoors when they're in season and shelter them when they're out of season.
