We have an area with mixed groundcover of vinca and ivy which used to have dwarf rudbekia in it. My husband pulled out all the rudbekia thinking they were weeds. Now we have volunteer rudbekia growing from seed in another area where it needs to be removed. I want to pull up some of the vinca/ivy and transplant it to another area to make room to move the rudbekia back there. When is the best time to do that and any suggestions on how to do it?