Best and Worst Yarrow Companion Plants

Yarrow (Achillea millefolium or A. filipendulina) is a plant equally at home in an overgrown ditch as it is a charming cottage landscape, to the extent that many people categorize this herb as a nuisance weed and nothing more. But, with the right approach, yarrow can be one of the most beneficial companions for the home garden.

Adding yarrow to your garden can deter unwanted pests while simultaneously rolling out a welcome mat to native pollinators. Yarrow may also improve soil quality over time by replenishing valuable nutrients.

In the rest of this article, I’ll dive a bit deeper into the benefits of this perennial herb and share some of my favorite yarrow companion plants to help get you started.

What Is Companion Planting?

Companion planting involves growing different plants together in the same space. The goal is for one plant to benefit the other(s) in some way, such as by providing necessary shade or deterring pests.

Any two plant species can be grown next to each and called ‘companions’. But that doesn’t mean they have a beneficial relationship. 

Some examples of companion planting are very subtle while others are glaringly obvious. One of those more obvious examples is the relationship between corn and pole beans (commonly planted together, along with squash, in something called a Three Sisters garden).

When grown in the same space, the pole beans will instinctively climb the corn stalks. The corn directly benefits the beans by offering structural support.

At the same time, the beans help anchor the corn to the soil. Beans, like all legumes, are also capable of transferring nitrogen from the air into the soil. So the beans return the favour by protecting the corn from wind damage and improving the soil quality.

Benefits of Planting Yarrow in Your Garden

Yarrow is famous for its medicinal properties. All parts of the plant are edible, and yarrow tea is historically very popular as a digestive aid.

While there are many people today who still grow yarrow for medicinal purposes, that only scratches the surface of the plant’s potential benefits. For the average gardener, yarrow is much more helpful in the ground than out of it! 

Pest Control

Yarrow is frequently touted as one of the best companion plants for natural pest control. It manages unwanted insects using a couple of different mechanisms:

  1. The yarrow plant produces odorous chemical compounds that some pests dislike. Though crushing the leaves tends to be the most effective — it releases the most chemicals into the air — you might also see decreased pest activity just by growing the plant in your garden.
  2. Yarrow flowers are beloved by beneficial predatory insects like parasitic wasps, ladybugs, lacewings, tachinid flies, damsel bugs, and hoverflies. These insects then feed on aphids and other common garden pests, naturally keeping their populations under control.

Better Soil Quality

Another awesome reason to grow yarrow in your garden beds is its innate ability to improve the soil around it. Here’s how:

Yarrow is able to grow in even the poorest soils because it uses a deep root system to access nutrients like magnesium, potassium, and calcium far below the soil’s surface. This also means that yarrow won’t compete for nutrients with more shallow-rooted plants close by.

Since the yarrow is a herbaceous perennial, it dies back to the ground each fall. All of those nutrients pulled up from deep in the soil are then released into the topsoil as the yarrow decomposes. So planting yarrow in your garden is basically like applying a layer of green compost each year (assuming you don’t remove the plant matter before it decomposes).

Aesthetic Value

There’s no denying that yarrow is an aesthetically pleasing addition to many garden beds. Most varieties flower for several months and attract a range of local pollinators during that time. And the plant’s fern-like leaves contrast nicely against other types of foliage.

Yarrow blossoms traditionally come in shades of yellow or white. If you like a bit more colour in your garden, however, I also highly recommend cultivated varieties like ‘Strawberry Seduction’ or ‘Summer Pastels’!

Summer Pastels

Choosing Companion Plants for Yarrow

Yarrow is a versatile herbaceous perennial. It’s fairly easy to identify in the landscape thanks to its clusters of small, brightly coloured flowers and feathery foliage. 

Yarrow can grow 2 to 3 feet tall on average and will survive in all types of climates and soil conditions. It’s native to most of the Northern Hemisphere but some regions classify it as invasive (largely because it can and will thrive almost anywhere!). 

This herb prefers full sun when available and will happily grow alongside other vigorous plants that enjoy the same conditions. Here are some such plants I recommend growing with your yarrow:

Fruits and Vegetables

Fruit Trees: Yarrow is a really nice perennial to plant around established fruit trees. It will help keep weeds in check while drawing valuable pollinators to the area (which will help produce a large fruit harvest!). 

Strawberries: Strawberries are attractive to a number of pest species, and planting yarrow can help control those populations by bringing in various predatory insects. Just be sure to leave a wide margin between the two, as yarrow is liable to choke out your strawberries.

Tomatoes: Yarrow and tomatoes are very popular companions. The predatory insects that yarrow attracts will happily feed on any aphids or spider mites attacking your tomato plants. 

Eggplants: Eggplants and tomatoes are closely related, so you can expect to see nearly identical benefits when growing yarrow as a companion. 

Brassicas: Brassicas like cabbage, broccoli, kale, and cauliflower are frequently hosts to pests like the cabbageworm. Grow yarrow nearby to attract this caterpillar’s natural predators, which include lacewings and parasitic wasps.

Cucumbers: Planting yarrow will increase the odds of tachinid flies and parasitic wasps visiting your garden. In turn, these beneficial predators will help control the populations of cucumber beetles and whiteflies.

Squash: Tachinid flies, which are drawn to yarrow, are a primary predator of squash bugs and their larvae.

Herbs

Rosemary: Yarrow and rosemary both enjoy sunny locations and well-drained soil, making them natural companions. The yarrow will help deter aphids and other pests targeting your rosemary.

Sage: Sage is another aromatic herb adapted to the same sun and soil conditions as yarrow. Plant them together in your garden to attract pollinators and predatory insects.

Thyme: This herb offers similar benefits as yarrow — it can control pests, attract pollinators, and maintain good soil quality. Thyme is tough and relatively low-growing, so I recommend planting it in front of your yarrow. 

Basil: Yarrow may protect basil from common pests like aphids. Some gardeners like to use yarrow to shade out their basil during the hottest part of the day. This is very clever but be sure not to let the yarrow choke out the basil!

Lavender: Lavender and yarrow may look quite different but they share similar growing preferences. This pairing is sure to boost pollinator activity with minimal maintenance.

Oregano: If you’re looking for another fragrant herb that will thrive in poor soil, try companion planting some oregano with your yarrow. 

Ornamentals

Roses: Roses are highly susceptible to pests like aphids and spider mites. Yarrow can increase the number of predatory insects in your garden — controlling the populations of said pests — and won’t compete with your rose bushes for valuable resources like water.

Daylilies: Yarrow and daylilies are surprisingly suitable bedfellows. Both enjoy full sunlight and these beautiful flowering perennials offer some cheery colour in the summertime.

Blazing Star: Blazing Star, or Liatris spp., is an eye-catching wildflower native to parts of North America. It loves lots of sun and is unbothered by low-quality soil. I highly recommend this perennial as a pollinator-friendly companion to ornamental yarrow.

yarrow and blazing star

Ornamental Grasses: Clump-forming grasses contrast nicely against yarrow and other cottage-style perennials. Opt for native species when possible to support local pollinators in and around your garden.

Columbine: Columbine is a nice option if you’re looking for visual interest that precedes yarrow in the spring. This somewhat early bloomer enjoys full sun but won’t suffer greatly if outgrown by the yarrow.

Bad Yarrow Companion Plants

In my experience, yarrow pairings that struggle to thrive are usually the result of mismatched sun requirements. Remember that yarrow is a full sun plant and needs at least 6 hours of bright light to really flourish.

Avoid growing yarrow with foliar shade lovers like hostas and ferns. I actually like to use yarrow as an alternative for the latter in sunny locations since the foliage is so reminiscent of an actual fern.

Another frequent problem gardeners encounter is yarrow’s rapid growth rate and competitive nature. Yarrow will spread quickly if given the chance and can easily choke out less vigorous companions. 

Even if yarrow doesn’t completely smother nearby plantings, it can grow dense enough to block crucial sunlight. 

For the best results, leave a bit of space between yarrow and other full-sun perennials like garden phlox, bee balm, coneflower, and milkweed. While some gardeners advise against growing these flowers with yarrow, I find they make good companions given adequate elbow room.

Finally, the yarrow is susceptible to powdery mildew, a common fungal disease. The powdery mildew strains that affect yarrow (Erysiphe spp. and Podosphaera spp.) may also infect crops like beans, peas, cucumbers, squash, carrots, celery, and brassicas.

I don’t think you need to avoid growing these plants together entirely — after all, many make good yarrow companions for other reasons. But I do recommend taking steps to prevent powdery mildew, such as prioritizing air circulation and planting disease-resistant varieties. 

You can find a great list of powdery mildew-resistant vegetables published by Utah State University.

If you enjoyed this article, here’s a link to Kohlrabi Companion Plants that you may find useful.

Citations

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.