Lemmon's Needlegrass

Bristly Yarrow (Achillea setacea) should be watered every other day for the first few weeks until the plant has become established in its new environment. After this period, it should be watered once a week. It should be watered deeply, enough so that the soil is moistened throughout each of its layers. In the summer, Bristly Yarrow can be watered more frequently if the soil begins to dry out, especially if the temperatures are warmer than usual. When watering, make sure not to over-water though as this can cause mold or root rot.

Bristly Yarrow (Achillea setacea) prefers full sun to partial shade for optimum growth. It is a resilient perennial species that can handle some periods of partial or full shade, however it will do best in an area with at least 6 hours of direct sunlight each day, during the peak of summer. That means that for ideal conditions, it should receive morning sun until late afternoon, although the exact length of time will depend on your local climate. To ensure good flowering potential, Bristly Yarrow should be given some afternoon shade during the hottest hours of the day.

Bristly Yarrow (Achillea setacea) should be pruned in late spring or early fall. Be sure to remove any dead or damaged branches and leaves, as well as any flowering stems that have gone to seed. To encourage bushier growth and more blooms, prune the plant back to within an inch or 2 of the ground. This will also help to prevent unnecessary seed dispersal, since the plant can be quite spreading. If you choose to selectively prune the plant, cut back to within a few buds of the desired shape. Pruning to shape should be done in early spring, before new growth appears.