Posted: 04/08/2014 at 09:04
Hypericum or Rose of Sharon is a thug that's difficult to dig out. The yellow form of lysimachia can get very happy and spread by root invasions. It's cousin, lysimachia clethroides alba, is much more attractive and much easier to dig or fork out or pull up after rain.
Alchemilla mollis is only a problem if you let the flowers go to seed. I cut them off anyway as I have never liked acid yellows and greens.
My echinops ritro is very happily seeding itself about but the seedlings are easy to hoe or pull up or dig up witha trowel and ot up for friends.
Phytolacca americana self seeds all over the place too but again is easy to deal with at seedling stage.