Yarrow, or Achillea millefolium, is a hardy perennial that belongs to the Asteraceae family. It’s drought tolerant and will weather long, cold winters with ease. It is equally happy in the ground or in containers. And the many varieties produce flowers in a range of colours including yellow, orange, red, white and pink. So, no matter where you live and what your flower preferences are, there’s likely to be a variety that will suit your garden.
Yarrow is commonly used as a medicinal herb. It’s often used to treat bleeding, muscle cramps and fevers and it’s sometimes used to prevent and clear blood clots and lower high blood pressure.
Yarrow is also used as a cleanser and in shampoo.
Be aware that yarrow can cause allergic reactions in some people (especially if you’re allergic to plants like ragweed, marigolds and daisies) and it is toxic to a variety of animals including dogs and cats. It should not be used by pregnant or breastfeeding women. Yarrow is known to interact with quite a few drugs so always seek medical advice before taking yarrow and before starting any new medication.
How to grow yarrow
Yarrow is usually propagated by division. That’s not to say it can’t be grown from seed, but chances are you’ll be buying a seedling if you’re shopping for yarrow at your favourite nursery. If that is the case, when you transplant a purchased seedling, give it plenty of space. Yarrow can spread a lot so you might need to plant it up to 24 inches or 60 cm from other nearby plants.
If you want to grow yarrow from seed, sow the seeds indoors a couple of months before your last frost date if you live in a frosty area or in winter if you live in a frost-free area. Cover the seeds with a thin layer of potting medium and keep them moist for at least 2-4 weeks.
Seedlings should be planted in a full sun position. Yarrow prefers a well-drained position but will tolerate pretty much any soil. Under the right conditions it can be a bit invasive in certain areas so just make sure you can control it if needed.
Once plants are established, you should only need to water them during severe droughts. They shouldn’t need to be fertilised and will generally resist most pests and diseases. Occasionally yarrow may be attacked by certain fungi (like powdery mildew) so if that’s a problem in your area just make sure your yarrow plants get plenty of air circulation.
Companion planting with yarrow
Yarrow is an excellent companion plant. It’s known to increase the amount of available copper in the soil so it’s a useful companion for any plants that need lots of copper. You can also plant it next to plants that are suffering from a copper deficiency.
There’s also some indication that yarrow may increase the essential oils of nearby plants, especially the aromatic oils of flowers. When this occurs, it strengthens the perfume of scented plants the flavour of herbs. It’s difficult to verify these effects because of how subjective perfume and flavour are but I reckon it’s worth experimenting with it in your own garden if you like yarrow.
I think the most valuable benefit of using yarrow as a companion plant is that it attracts beneficial insects such as predatory wasps, hoverflies, damsel bugs and ladybirds. Yarrow also inhibits the germination of a variety of weed seeds. It’s even competing well with couch grass in my garden.
If you’re planning to sow pepper seeds in your garden, don’t sow them near yarrow plants; yarrow inhibits the germination of pepper seeds.
Yarrow in permaculture
Because it inhibits the germination of weed seeds, attracts beneficial insects and can be used as a medicinal herb, yarrow can be a powerful plant in a permaculture garden. If you plant it near other culinary herbs, it may also help you make tastier food. It may not be a staple crop but yarrow still has a lot of permaculture value.