We use cookies to allow us and selected partners to improve your experience and our advertising. By continuing to browse you consent to our use of cookies. You can understand more and change your cookies preferences here.

14 July 2021

How to grow achilleas

Bright colours and brilliant structure, these summer perennials are a great choice for well-drained soil
CT
Ceri Thomas
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. We wanted to see which varieties gave the greatest impact and stayed looking good for longest.

How to grow achilleas: month by month

January
February
March
April
May
June




FLOWERING
FLOWERING
July
August
September
October
November
December
FLOWERING
FLOWERING
FLOWERING
FLOWERING
FLOWERING

Best achillea varieties

Which members can log in now to see the full results and which are our Best Buy varieties. If you're not a member, join Which? to get instant access.

Best Buy achilleas
What it looks like
Variety name
Height x spread
160 x 80cm
A dramatic plant, covered in large, golden flower heads held above mid-green, fronds of foliage, this variety makes a striking addition to any border and holds an RHS Award of Garden Merit (AGM). In our trial, it flowered solidly, giving a brilliant show even at our northern site. It was also one of the tallest varieties on trial, but even so, it didn’t need staking. Flowering started in May and continued past the end of October. Peak flowering: May-Oct
What it looks like
Variety name
Height x spread
85 x 60cm
In contrast to the drama of some of the taller varieties, the delicate pink flowers of this variety produced a much lighter, airy plant with thinner stems and less dense flower heads. The pink flowers started a dark or mid tone and faded as they got older into paler shades, adding interest. The foliage was also delicate and feathery. The flowers lasted well at both trial sites, flowering from May through to November. Peak flowering: May-Nov
What it looks like
Variety name
Height x spread
80 x 70cm
This was a more subtle plant than other varieties, with softer, lemon yellow flowers set off by silver-green foliage that was striking in itself. It flowered consistently between May and October at both our trial sites. It only reached 60cm tall, making it ideal for smaller spaces, but the heavy heads mean it needs a bit of support to look its best. It also holds an RHS AGM. Peak flowering: May-Oct
What it looks like
Variety name
Height x spread
85 x 60cm
Slower to establish than other varieties on trial, this variety kept us waiting until June for the first blooms at both sites, but they were worth the wait. A rich, rusty red with bright yellow centres that faded to shades of terracotta as they got older, it made an interesting display. The flowers kept coming to the end of August then paused before a later flush got going. Despite the slightly shorter display, the lovely colours made it a worthy Best Buy.  Peak flowering: Jun-Aug

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