Yarrow

Description: Fern-like leaves on stem. White flower heads in flat clusters.
Peak Season: Summer (June - August)
Treatment: Herbicide

Yarrow is identified by its narrow, fern-like leaves which grow alternately on the stems. The leaves themselves are strongly scented. White flower heads form in flat clusters similar to an umbrella. The root system consists of rhizomes (horizontal stems from which roots protrude) and fibrous roots. In the lawn, it is typically through these rhizomes that yarrow spreads and thickens.

When will I see Yarrow? Clover is a summer perennial weed, meaning it can live for years. Therefore, you may see it in your lawn throughout the year as long as there is no snow, peaking during the summer months.

How do I get rid of Yarrow and how long will it take?

Yarrow is one of the harder weeds to kill with a selective herbicide, but it can be done. Apply this every 5 to 6 weeks. You should start to see damage and withering to the leaves after the first or second application, with the plant completely killed after 6 consecutive applications.

If you don't want to wait for the whole summer, you may consider weeding them by hand. When doing this however, be sure to pull out the whole root system as they will continue to grow if not completely removed.

How do I prevent Yarrow from infiltrating my lawn?

While there is no way to perfectly keep out all yarrow, there are a few things you can do to help prevent new growth in your lawn. These include:

  • A Pre-emergence herbicide in April or May to help prevent germination from new growth.
  • Mowing your lawn on the second highest setting to help crowd out any potential growth and block out the sunlight.
  • Fertilization and deep, consistent watering will help your lawn grow and crowd out the yarrow.