I watch a lot of BBC Gardeners World, which gives me a lot of inspiration for making changes to my own garden. I tried looking for a free and open source program for designing gardens in the openSUSE package search. The only application that I found was Rosegarden, a MIDI and Audio Sequencer and Notation Editor. Using google, I found Edraw Max, an all-in-one diagram software. This included a Floor planner, including templates for garden design. And there are download options for various Linux distributions, including openSUSE.