Well first your garden looks lovely and the lady's mantle offers lots of color. I have been able to control this self seeding perennial in my own garden by clipping off all the flowers as soon as they are done blooming. This stops the spreading to other beds. If you do decide it is just too much of a bed hopping tramp for your garden then dig out the plants as soon as the flowers show is over as if you wait until fall the soil is more dry and harder to dig. The roots are not easy to remove so be prepared for a deep dig. Then cover the area with a fresh mulch to help control the many seeds that will have fallen onto the soil. Good luck and Keep growing, Marianne Binetti