I wouldn't like to have to cut you're garden grass
It is all sand where I live with no ocean.

I'm going for the Maplin IR_Display. Do you think it will put enough light out to take a picture at a reasonable shutter speed without using the flash?
I would guess yes if you can place it close enough to the target like you had the PIR in the cereal box. It will be directional like a flash light (hand torch?).