Optimize your garden plan, and learn about permaculture in the process! powerplant provides intelligent planting suggestions which maximize positive crop interaction for the mutual benefit of all your crops. It also helps you track the progress of your garden with planting schedules and customizable tasks.
Currently in development. You may try a demo of a recent development snapshot online here.
Basically you need to have Node.js installed, then follow the instructions in the development documentation.
Join github and do a PR or create an issue. Developers can be reached from #powerplant @ freenode. For other communication options see the wiki.