PLANT is: Fourpetal Maple: causes an exotic fragrance that brings more people to your store. Once it shows in the gold pot, you get another you can sell. Selling price is 30 isola-bucks. Cross pollenize a Fourpetal Maronta with a Citrus Maple.
Get yourself a turtle! A stone turtle bought in supplies for 50 iosla-bucks can be clicked to spray water. This spraying can bring in extra customers.
I've found that selling one plant just does not work. You need at least two, and at best three plants for sale at one time. Remember just because a plant is depleted of seeds and ready to be sold, it still holds POLLEN. If this is the only plant you have to sell, use it's pollen to cross-pollenize another plant and wait for seeds to grow then sell both plants.
After restarting the game several times I've found the same thing - the first customers seem to be lookng for a Bluestar Reptons. Having more of these to sell brings better profits and more customers!