No experience.
2006 Yarrow spread by shallow underground runners and form clumps of plants. In late Spring when the yarrow plants were just starting to grow, I dug some small plants . I left the connected plants intact and planted some in my big rock garden and my side rock garden. All lived so yarrow must transplant well.
2008 The above image is a transplanted yarrow in my big rock garden. These plants are larger than the ones I transplanted in 2006.2008 I would like to encourage more yarrow plants to grow in my big rock garden, both from seed and by transplanting.