Troubleshooting
Woolly yarrow problems — and how to fix them
Woolly yarrow (Achillea tomentosa) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Crown rot in winter wet
The chief risk for this species is sitting in cold, wet soil over winter. Plant on a slope or raised bed, improve drainage with coarse grit, and avoid mulching directly over the crown.
Loss of compact habit
Mats can become open and die out at the centre after several years. Divide clumps every 3–4 years in spring, replanting vigorous outer sections into freshly prepared ground.
Aphid colonies
New growth in spring can attract aphids. A strong jet of water or insecticidal soap spray controls light infestations; ladybird and lacewing predators usually provide natural regulation.
Prevent woolly yarrow problems before they start
Most woolly yarrow issues are care-mismatch, not bad luck. Dial in the basics:
Looking for woolly yarrow in general rather than its problems? Read the full woolly yarrow care guide — light, water, soil and feeding.
Woolly yarrow problems — FAQ
Why is my woolly yarrow crown rot in winter wet?
The chief risk for this species is sitting in cold, wet soil over winter. Plant on a slope or raised bed, improve drainage with coarse grit, and avoid mulching directly over the crown.
Why is my woolly yarrow loss of compact habit?
Mats can become open and die out at the centre after several years. Divide clumps every 3–4 years in spring, replanting vigorous outer sections into freshly prepared ground.
Why is my woolly yarrow aphid colonies?
New growth in spring can attract aphids. A strong jet of water or insecticidal soap spray controls light infestations; ladybird and lacewing predators usually provide natural regulation.