Honestly, in the yard, put 4 gnomes in the center and then constantly farmed baby verde, the amount of money you get per second is more than any other plant, being $75 ever 30 seconds. I've looked through all the other plants and none of them, save some of the level 13 plants, seem to put out a quicker cash flow than this method, even Verde.
You will be constantly harvesting but you will never loose significant time between the quickly budding buds, and the only time you switch out your crops for the slower verde is when you earn the field and can't keep up with the planting and harvesting on two plots.