Cultivated varieties of achillea are attractive, ornamental herbaceous perennials, which will brighten up borders for many months. However, wild yarrow can become a problematical weed – colonising large areas – especially when it gets into the lawn.
Yarrow grows in any soil, but is particularly problematic in light, chalky or gravelly soils. It is very drought resistant, and often starts to take over in hot weather and during droughts. In such conditions, which don’t favour other plant or grass growth, yarrow quickly establishes and grows prolifically – especially in lawns, which are weakened by dry conditions – producing large patches.
The mats of foliage can smother and kill smaller plants. The roots and rhizomes (underground stems) can grow in between the roots of cultivated plants, making them awkward to remove and control. It produces low mats of foliage in lawns, which can be difficult to control.