A mirror is a clever design element for small spaces. It reflects light and creates depth, making a compact area look so much bigger. I don't have a small garden anymore but love the idea of using a mirror anyway.
I don't have a fence, but like this idea. Find old windows, replace the glass with mirrors and put these on your fence (if you can). The mirrored image of your garden on the fence will make your yard look bigger. It's an easy trick!