Assuming you just mean 'vegetatively' i.e. by cuttings...
Some are no doubt easier than others, but I have no trouble dividing
P. moranensis types around March here in the UK, when they form a
tighter 'Winter rosette' for a short time. I have also grown them
from leaf cutting of these Winter leaves. The large floppy leaves are
no use at all.
P. esseriana sometimes seems to eject excess leaves from the
centre of the rosette and these root and grow with no problems.
The 'resting bud' forming species like P. grandiflora and vulgaris
form lots of gemmae around the main bud which can be planted
separately.
-- Clarke Brunt (clarke@brunt.demon.co.uk)