Most variegated plants require more light because they lack chlorophyll. I'm not saying direct sunlight just lots of light.

As for the decapitation project: Not sure which part of the plant you placed in the shade? The beheaded portion or the remaining body? Usually, one allows the top portion to callous for several days depending on the thickness of the stem and re-plant it, watering only very little and no direct sun until you see new growth. The base can be put out anytime and should grow new pups from the old leaf scars. Of course, if these plants have been indoors, a period of acclamation is necessary.

Actually, I put both in the shade. The head has already begun rooting and I've placed it in partial sun, where it's already growing a new inflorescence. I've also put the body in partial sun.