Sansevieria
Sansevieria trifasciata (German: Bogenhanf) is a nice green
plant that grows easily and doesn't need much water or light. It comes
in several variants, a tall, slender one (see picture on the right), and one of short
stature (called the variety "Hahnii", see below). Different leaf color schemes exist, though the ones with a
yellow border around the leaves cannot be propagated: the children will
always have plain green leaves.
Sansevieria can be a bit delicate when
she's young, then she will not make any new sprouts and grow only from
one rosetta. But Once she has decided she likes her environment, she
can develop a rank root system! You can
influence this by choosing where you pour the water: if you pour from
the top, inside the rosettas, more leaves are formed, and if you pour
from below, into the saucer, more roots grow. But somehow or other,
you will need to re-pot your darling...
Now for the propagation. With the tall variant, you can cut a
leaf into pieces, each about 8 cm (3 inches) long. Leave these to dry,
a week or 10 weeks, it doesn't matter. But remember which end of the
piece was at the top and which pointed towards the bottom. Then,
simply put the pieces into some soil so they stick out with the top
half (be sure to get the direction right). Water regularly, but make
sure the soil is not too wet. Several months later, a new shoot will
emerge from the soil – and there is your new plant!
With variety Hahnii, the shorter one, the same technique can be
applied, only with the limitation that one leaf doesn't give so many
pieces.

Another possibility is to separate one rosetta from the main
plant. This is easily done while re-potting - it may also help to
increase the average lifetime of your pots if you remove the outer
rosettas - when Sansevieria decides she
needs more space for further expansion, she may not feel inclined to
respect such things as the pot she's growing in and she may just grow
right through it (sorry, no picture available, but I have seen it, you
can believe me, and I try to prevent a repetition).
Just break
away some of the outer rosettas, together with some smaller roots to
guarantee the nutrient supply for the child. You probably need to
break one of the bigger roots where the shoot is attached to the main
plant. Then put the child into its own pot - finished!