How To Divide And Control Yarrow (Plus Other Tips For Managing The Spread)

Yarrow (Achillea millefolium) is a hardworking plant that brings bees and butterflies to the yard. Growing and caring for yarrow is, frankly, pretty easy, which is why these umbrella-shaped flowers are so popular amoung gardeners. It grows vigorously without much help; so vigorously, in fact, that it could become weedy or even invasive in some areas. So, it's no surprise if you're thinking your yarrow has overgrown its space and needs some thinning out. The good news is that this resilient, rhizomatous plant is easy to divide. You can do so early in the season or later in the fall — all you need is a spade.

Start by digging at the edge of the plant with your spade. Typically, the plants come apart fairly easily as you lift. Be sure to break up individual plants but take care not to damage the roots more than necessary. You can also dig through the foliage to look for empty spots, as sometimes the plants are deceiving. What looks like one big plant is often many little ones, and by sorting through the foliage, you can often locate small plants that are easy to dig out of the ground. However, if you want to keep your yarrow from spreading so it never gets a chance to take over your flower bed, there are other ways to control this plant, including deadheading and growing it in containers. 

Yes, yarrow spreads via rhizomes, but that doesn't mean it doesn't also produce seeds. Birds, like mourning doves, actually love yarrow seeds, but if you want to help control the plant's spread, deadheading is going to be key. It's known to be aggressive when self-sowing, so if you don't want it popping up in unexpected places, cut those flowers are soon as they are spent. The good news is that deadheading yarrow, just like many other plants, will encourage it to rebloom and keep on flowering through the summer.

For the best results, cut the stems with spent blooms just above the lateral bud. Doing so will encourage the plant to grow new shoots from the bud, and these will eventually flower again. Once the yarrow is done blooming for the season, you'll want to remove the entire stem by cutting it off at the base of the plant. As with any other plants growing in your garden, avoid these mistakes when deadheading your flowers.

Another way to keep yarrow from spreading is to refrain from putting it in the ground in the first place. While there are some mistakes you should avoid when growing yarrow in a container, this hardy plant can thrive under almost any conditions. So, it's definitely a candidate for life in a pot, where its rhizomes have no chance of spreading. Yarrow tends to like dry soil, and it does not need much fertilizing, so it's well-suited to the challenges of container life. The key to growing potted yarrow successfully is to plant it early enough in the spring and to water it when the soil dries out about 2 inches beneath the surface. 

There are many benefits of growing a container garden, although the practice isn't always simple and mistakes are easy to make. So, if you're undertaking this challenge for the first time, be sure to do your homework, but rest assured that yarrow could be a great addition to a potted garden. In fact, it's a forgiving plant for beginners to get started with.