I'm a little bit surprised that this hasn't been mentioned yet, as the lazy-gamer's key to chocolate riches: weeds. For me, there were two that worked, depending on the level of my laziness.
1. Poison Ivy. Being a weed, it plants itself, needs no watering, and drops more seeds when the flower is done blooming. The flower head itself is worth 100 coins, and on average the plant drops three seeds, which will then replant themselves. I let my posion ivy garden grow by itself while I watched TV, checking in during commercials to sell the flower heads and extra seeds. Very lazy, very easy.
2. Venus Pinata Traps. The flower head sells for 360 coins. The difference is, as far as my experiences have shown me, the venus pinata trap won't pop itself. You have to hit it with your shovel after the flower has bloomed. Doing this nets you the flower head as well as three seeds (which can be sold for 72 coins each). If you sell two seeds and replant one, you're making five hundred coins per plant.
The second is the method I used to get to 100k coins, because I really hate planting chili's. I used a brand new garden so that I didn't have to worry about sick pinatas, and I had eight plants blooming at once. It took me less than an hour to get all the way to 100k.
So hopefully this is a saner alternative to anyone else annoyed at fertilizing chilis.