Houseplant hacks: should plants rest in the dark over winter ?

The problem
Winter plant advice is full of contradictions. Rest your plants; don’t rest your plants. Move them to a cooler spot; keep them warm. One common tip is to put certain houseplants in a dark, cool spot, to mimic natural dormancy and give them the rest they need.

The hack
Some plants need a period of reduced light, cooler temperatures and minimal watering to complete their growth cycle. Forcing this dormancy by moving them somewhere darker and cooler in winter is said to result in stronger growth, better flowering and a healthier plant come spring.

The method
Move cacti and succulents to a cool, dark place from around October to March. Reduce watering dramatically, stop feeding entirely and keep them between 5C and 10C if possible.

The test
I moved some cacti to an unheated room for winter and put some in total darkness. In spring, the ones with low light were compact, firm and pushed out new growth quickly. The ones in total darkness etiolated (became unnaturally long, pale and weak).

The verdict
Dormancy works for the right plants. Cacti will benefit from a cooler, lower-light rest in winter, though they don’t like total darkness. Tropical plants will simply get stressed.