This Stunning Blue-Purple Flower Will Keep Weeds From Taking Over The Garden

Aggressive weeds can turn a garden from an idyllic dream into a constant struggle. While mulch, regular maintenance, and other strategies can help, in some cases the best way to fight against weeds is with another aggressive plant that can outcompete them. Of course, if you're going to use plants to help prevent weeds in the garden, it's important to choose ones that are native to your zone and will also add beauty and other benefits to your yard. Luckily, blue mistflower checks all of those boxes.

Blue mistflower (Conoclinium coelestinum), also sometimes called hardy ageratum, is a beautiful wildflower native to the eastern United States. Unlike true ageratum (Ageratum houstonianum), it is a perennial and is hardy in zones 5 through 10. The reason blue mistflower makes such a good plant for keeping weeds from taking over, is because it is so aggressive, itself. Spreading by both seeds and rhizomes, it can easily outcompete many other plants, including invasive weeds. Even better, it's a hit with pollinators and is seldom bothered by deer. 

Blue mistflower seeds and plants aren't always available in large garden centers, but they can often be found in shops that specialize in North American native species. They also divide well, so you may be able to get some from friends or through plant swaps. If you opt to buy blue mistflower seeds, be sure to sow them in the autumn so they can experience natural winter seed stratification. They'll grow best in a space with plenty of moist and fertile soil and at least part sun, though full sun is best.

Blue mistflower is an extremely tough plant, and you can even mow it if you want. If left alone, it will grow up to 3 feet tall and naturally form clumps thanks to its underground stems, called rhizomes. Because of its preference for moist soil, you may need to water your blue mistflower regularly if it isn't planted in an area that stays damp naturally.

While blue mistflower is a beautiful plant, you should think carefully about where to put it. Because it is so aggressive, it may not only outcompete weeds, but also your favorite slower growing flowers. Blue mistflower's ability to attract pollinators like butterflies and moths makes it a great addition to pollinator gardens, and its preference for moist soil can allow it to feel right at home in a rain garden.

North American native species like cardinal flowers, bee balm, and Joe Pye weed can make excellent companions for mistflowers. All these plants are fast growing and spreading and enjoy moist soil and plenty of sun. This means that not only do they enjoy similar conditions to blue mistflower, but they also are unlikely to be outcompeted by it. They are also all popular with pollinators and can easily turn your weedy garden into a gorgeous wildflower meadow and a pollinator paradise filled with a variety of butterflies.