How to grow achilleas

Achilleas are beautiful, bold perennials for the summer border and will return year after year. Their tall stems and flat flower heads can provide structure and colour, ideal for prairie planting or contrasting with softer schemes. They’re a great choice for poor, dry soils, which can be tricky to find plants for. In fact, their growth is weaker in rich soil and they don’t live as long in wet conditions. 

Achilleas look wonderful in informal cottage gardens and they’re a useful addition to wildlife gardens as they’re popular with pollinators. 

Which? Gardening magazine wanted to see which varieties gave the greatest impact and stayed looking good for longest.

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Key facts

PLANT TYPE Perennial 

POSITION Full sun 

SOIL Well drained soil

How to grow achilleas: month by month

Best achillea varieties

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How we test achilleas

We chose 21 varieties of achillea, selecting those which were the most widely sold and well-known  of those available. We alsoincluded a few newer varieties.

We grew three plants of each variety at our trial garden in Capel Manor Gardens, north London, where the weather is mild with moderate rainfall, and at Alnwick Garden in Northumberland, which has similar rainfall to north London but is colder in winter and cooler in summer.

We assessed our plants for all the criteria listed over two years. In autumn of the first year, we cut them back to ground level. 

As we were growing the plants through the summer of 2020, when accessing our trial ground wasn’t always possible, we weren’t able to deadhead our plants as regularly as we liked. However, as mature plants can become straggly in late summer, we lightly trimmed the plants in July to encourage them to continue flowering.

Caring for your plants

Planting

Plant in full sun in well-drained soil around 40-50cm apart. If you have heavy or wet soil, introduce some grit to improve drainage. Achilleas have aromatic leaves and flowers, which some people find unpleasant, so you might want to avoid planting them in large groups or where you will brush past them.

Deadheading

Deadhead blooms regularly to keep your plants flowering throughout summer and divide large clumps in autumn or spring, around every three years. Be careful when handling achilleas if you have sensitive skin as they can cause irritation. Wear garden gloves.

Going into winter

Cut back all the stems to ground level once they start to look messy. This can be as late as February as in a cold, dry winter they'll stay looking good for a long time and be a valuable resource for wildlife. They'll regrow in spring.

Propagating

You can make new plants by digging up the clump in spring or autumn and splitting into smaller pieces, each with their own roots and shoots. Replant the best ones and throw away any that are weak.

Common growing problems

Greenfly

Achilleas are generally trouble-free, but keep an eye out for greenfly (aphids). If you spot any, you should be able to keep them at bay by simply wiping them off. Achilleas are a short-lived perennial, which will need replacing them every few years.

 Read more about greenfly