Answer: Although azaleas do well in dappled shade or gentle morning sun, they do not usually thrive in deep shade. They also tend not to do well in raised containers because their wide spreading and shallow root system just can't handle the abrupt temperature changes and rapidly drying soil very well.
For an evergreen for a totally shaded box you might consider a variegated aucuba shrub clipped to stay in scale or possibly, for a more elegant look, an English ivy trained as a topiary. Both of these would still require careful attention to maintaining an evenly moist soil but they would have better chances of staying healthy than an azalea would. You could also add impatiens or caladiums for some extra sparkle during the summer.
I hope this gives you some ideas.
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