I managed to sell a plant for $2000, but only once. After that, customers refused to buy even at $2000 though I left it to sell overnight. Since then the highest I've sold is $1950. I bred a bunch of these, made a pile of money so that I afford instant growth to experiment cross-breeding.

I've only explored 62 breeds, with about 17 types flowers so there might be other higher selling plants that I have not come across.

Do certain flowers bring in more money than others? I noticed one particular flower type seem to fetch more money. Also, plant food seems to work on only a couple of plant types (i.e. can encourage the flowers to bloom more vigorously.) The price of the plant increase as I add plant food.