Woolly yarrow

Questions about woolly yarrow

Does woolly yarrow need sun or shade?

Woolly 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 woolly yarrow grow in?

USDA zones 3 to 7. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).

Above zone 7 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.

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

When does woolly yarrow flower in my zone?

In zone 5 it flowers late May to early July. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.

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 woolly yarrow be planted?

12 in (30 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 18 in (45 cm), so a group knits into one patch.

It grows 8 in (20 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many woolly yarrow plants do I need?

At 12 in apart, set out in staggered rows:

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

In a mixed border, plant it as threes and fives, along the front and just behind it.

In the bed above, the planner used 19 in four groups.

Is woolly yarrow poisonous to dogs and cats?

Yes: mild toxicity to dogs, cats and horses. Can cause vomiting and diarrhoea in pets if eaten.

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

Is there a pet-safe plant like woolly yarrow?

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

• Three-toothed cinquefoil: the same job in a bed, the same size and the same flowering time; white, not yellow, keeps its leaves in winter.
• Rock cress: the same job in a bed and the same size; flowers mid April to early May, white or pink, not yellow.
• Red creeping thyme: the same job in a bed and the same flowering time; 6 in shorter, red, 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 woolly 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.

What flowers after woolly yarrow?

Woolly yarrow is over by early July. These start as it finishes and carry the same spot on, so it never goes flat:

• Sedum 'Dragon's Blood': from late June to early August, 4 in tall, to stand in front of it and cover its fading stems (a recorded partner).
• Black-eyed Susan: from mid July to mid September, 24 in tall.
• Butterfly weed: from late June to early August, 24 in tall.

What does woolly yarrow look like in winter?

Woolly yarrow holds some of its leaves into winter, more in a mild year or a sheltered spot, and they look tired by March. Cut the old ones off as new growth starts.

Is woolly yarrow good for bees and butterflies?

Woolly yarrow is visited by bees and butterflies.

It is native to the United States.