Yarrow

Questions about yarrow

Does yarrow need sun or shade?

Yarrow grows in full sun (6 or more hours of direct sun a day).

It wants dry, sharply drained soil, on the lean side, with no feeding, and little watering once settled. Once settled in, it stands drought.

What zones does yarrow grow in?

USDA zones 3 to 9. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does yarrow flower in my zone?

In zone 5 it flowers mid June to late August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should yarrow be planted?

18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.

It grows 24 in (60 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many yarrow plants do I need?

At 18 in apart, set out in staggered rows:

• 5 to fill 10 square feet (about 1 m²)
• 7 for a single row 10 ft (3 m) long
• 17 to fill a 4 × 8 ft bed on its own

In a mixed border, plant it as a group of three or five, with a second group further along in the other number.

In the bed above, the planner used three in one group.

Is yarrow poisonous to dogs and cats?

Yes: mild toxicity to dogs, cats and horses. Can cause vomiting and drooling in pets if eaten. The sap may irritate sensitive skin.

Rated from NC State Extension and the ASPCA. Where references disagree, the more cautious rating is used.

Is there a pet-safe plant like yarrow?

These come closest to doing what yarrow does, and no toxicity is recorded for them:

• Prairie coreopsis: the same job in a bed and the same colour; 4 in taller, flowers mid June to mid July.
• Common blanket flower: the same job in a bed, the same size, the same flowering time and the same colour; medium leaves, not fine.
• Tennessee coneflower: the same job in a bed, the same size and the same flowering time; pink, not yellow.

Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.

Do deer eat yarrow?

Mostly not. NC State lists it as resistant to deer and rabbits. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.

Will yarrow spread?

It spreads sideways, by runners or roots; the risk of it taking over is moderate. Spreads by underground runners and self-seeds, especially in rich soil. Divide every 2 to 3 years to keep it in bounds.

What flowers after yarrow?

Yarrow is over by late August. These start as it finishes and carry the same spot on, so it never goes flat:

• Garden chrysanthemum: from mid September to late October, 24 in tall.
• Sedum 'Autumn Joy': from mid August to mid October, 24 in tall.
• Autumn moor grass: from mid August to early October, 16 in tall, to stand in front of it and cover its fading stems.

What does yarrow look like in winter?

Yarrow dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.

Is yarrow good for bees and butterflies?

Yarrow is visited by pollinators, bees, butterflies and beneficial insects.

It is native to the United States.