Posted: 21/03/2013 at 15:57
As suggested the celandine will not need any encouraging to spread. It can be invasive but if you are happy to have it grow in a wild area then you should be ok. It tends to die away after flowering and rweturns the following Spring.
All the rest will eventually spread either by seed or by splitting but that will take at least a couple of years for the clumps to build up enough for you to split them up. If you want more any quicker then buy in bunches in the green in Spring after they have flowered. Fritts are in the nurseries in flower now. you can also grow your own from seed. Mine are in their third year and I will probably plant them out this year into the garden.