The bad thing about succulents is that they’re very brittle. It’s also the good thing about succulents, in that any time you knock off a fat, brittle leaf you’ve got the beginning of a brand-new plant. I’m talking about succulents with smooth, fat, fleshy leaves, not the kind with spines, like cactus.
While most typical house plants’s leaves need to be yanked or cut off, most succulents’ leaves will fall off if you look at them sideways. Accidentally brushing against them, moving pots about and jostling them slightly almost guarantees some leaf drop. It’s a little heartbreaking to spoil the symmetry of an established plant or to accidentally lop leaves off one that’s just beginning to take off, but the opportunity propagation helps to take the sting out. Got dismembered leaves? Make new plants.
Leaves are the start of new succulent plants. Simply let them sit where they fall onto the soil surface. At the leaf base, you’ll find new roots beginning to grow out into the air. These roots will find their way down into the soil, with no help from you. A new rosette will form at the base of the old leaf, eventually growing into a copy of the original plant. Of course you can help them along by re-positioning the leaf to a roomier spot, or in another pot altogether.
Leaves root best in a bright sunny location. While succulents are drought tolerant plants, root formation seems to progress better if the air is a bit more humid than the usual North American winter house. I find my own succulent plants that grow on a drafty (and therefore moister) western window sill are quicker to make roots than those on a dryer south-facing window. The higher humidity seems to coax out the aerial roots.
In my unheated south-facing porch where humidity is high (around 50-60% precisely because it’s not heated) my jade plant (Crassula) stems are sending out aerial roots while they’re still attached to the plant. Succulents seem to have a bit of wanderlust that way.