Maintaining and cleaning a garden window is a little more involved than, say, a more conventional double-hung window. First, you'll have to clear away any obstructions (plants or other items) and remove the shelf from its brackets. Vacuum or wipe away debris around the window base, then wipe down the interior panes. Clean shelf separately. The trickier part will be cleaning from the outside, which may require a ladder if the window is located on an upper story. Spraying down with a hose and/or scrubbing with a sponge is recommended, as there will likely be more buildup on the exterior. Maintain operation of the venting windows by oiling the hinges with a spray lubricant after cleaning.