Yarrow flowers will become faded and brown over the course of their growing season. You will want to deadhead these unattractive spent flowers not only for aesthetic reasons, but also to encourage further blooming. This deadheading, or yarrow trimming, is advocated because yarrow is an aggressive self-sower.

How do you keep yarrow blooming all summer?

Deadheading Yarrow Plants

Deadheading allows the plant to redirect its energy back toward growth and making new flowers, which will prolong the blooming season, according to PennState Extension. It takes little effort to deadhead yarrow, but you need to do it continuously throughout the blooming season.

Should yarrow be cut back after blooming?

Cut back yarrow to within 6 inches of the ground after it has finished flowering. In colder climates, cut it back as one of the last chores in your garden before the snow flies. In warmer climates, cut it back in the spring before it begins to bud.