If they get to grow to out of control, then you will need to divide the plants. You will need to cut back the plants first, and then pull plants out of the ground from the roots up.
Pick another spot you would like to grow them, and dig into the soil and plant the flowers. Space each plant about a foot apart.
With them growing so wildly throughout your garden, you can pick how you would like to grow them. Do you want a garden with just cranesbill covering the ground? Or do you want to use them as a border to your finest garden?
Whatever you choose, they are a great addition to have to your springtime garden. They are so low maintenance, and yet so pretty to look at, anyone can grow them!