SketchUp

SketchUp, Google's free design software needs to be installed on your computer. Not purely for garden design, it nevertheless includes landscape templates.

Rather more fully-featured than some online tools, SketchUp lets you upload a photo, as well as create objects from scratch. How useful you find that could depend on your creativity and willingness to learn this generic design programme for beginners.

PROS: Can upload your own photo; plenty of features.

CONS: Possibly harder work, and more complex, than some garden design tools.

Installation

Get PlayOnLinux installed. A simple apt-get thingie wossname. After that, launch the program and search for SketchUp using Actions > Install a program. The software is listed under Accessories, if you are wondering. After that, the program will install and configure a few dependencies, and then configure SketchUp. You can use the wizard to download the setup file, if you don't fancy doing a manual download yourself.