I remember stumbling across http://www.plantwithbloom.com/ in the past and thinking it was amazing. Consider this at least a small thank-you for your efforts!
I'm just not sure how to market it. I was going down a path of appealing to data-nerds with yards, focusing on the data techniques used to make decisions.
I've also experimented with using a physics ending to design beds, but haven't got it tweaked right: http://www.plantwithbloom.com/physics.html
(pretty fun if you want to see some plants get wrecked)
The value seems too low as it to get people purchase it. I'm considering partnering with nurseries, but the build out to use their inventories would be ambitious.