Diffused-Lighting is a method of scattering light in many directions by passing it through some medium; example,frosted glass; or reflecting off of an irregular surface.
We know what happens when we reflect a beam of light off of a flat regular surface such as a mirror.
Shadows are crisp and generally speaking, beam departs the target at the same angle it departed the light source.
but what if we reflect that same light beam off of an irregular surface? The beam will be scattered in all directions.
This gives the light a glare-free quality with softer shadows. Diffused-Lighting is useful for outdoor areas, quiet areas of decks, patios and all areas used for relaxation and recreation. This technique works well with area lighting.
... garden lighting feels more like art than science...
For Diffused-Lighting in you garden position a light source behind some translucent material such as frosted glass, a canvas panel , or simply the globe or plastic panel supplied with your outdoor light fixture.
By the way, in certain situations, you may be able to use reflection to create that diffused glow that you are looking for.
Try reflecting light off of nearby objects such as walls, stones, even the grass itself.
This certainly wont be appropriate in all situations, but keep it in mind. Anyway, garden lighting feels more like art than science. Explore!