Read Thread: Night boxes at an event
Hidden in an open field in pouches with reflective tape, everyone uses flashlights. Stagger them out in groups of 4 onto the field with a very a visual map of clues. This is if you're looking for inexpensive and easy way of doing it.
Using reflective tape or paint, then hide them in trees as well as on the ground.
We've used glow sticks in peanut butter jars with the stamps.
Luminaries with electric tealights.