Giant coneflower

Giant coneflower: how do you recognise it?

Habit

Perennial with a low rosette and upright, almost leafless flower stems up to 2 m tall; about 60 cm wide.

Foliage

Large, oval to spoon-shaped, blue-grey with a waxy bloom; the leaves on the stem are smaller.

Flower

Yellow flowers with drooping petals and a very tall, dark brown cone, from July to September.

Seed

The cones darken after flowering and stay standing for a long time; they hold plenty of seed.

Roots

A fleshy, slowly widening crown; an old plant resents being moved.

Flowering: July–September · Plants: March–May and September · Pruning: March

Why grow it?

• The blue-grey foliage is attractive all season, even when the plant is not in flower.
• Flowers on stems of up to 2 m add height and an airy effect at the back of the border.
• The tall, dark seedheads stay standing in winter and are eaten by birds.
• Bees visit the flowers in summer.
• Hardy and easy: no summer pruning and little care.
• A striking, graphic plant that is still uncommon in gardens.

Giant coneflower: where does it grow best?

• Full sun: it flowers best there and the stems stay sturdy.
• Loam or clay that stays moist, acid to neutral; heavy soil is no problem.
• Normally moist: not too wet in winter, as the rosette may rot.
• Site it in shelter or at the back of the border: 2 m stems catch a lot of wind.
• Allow 50–60 cm of space per plant.

Light

Sun

Soil type

Loam or clay

Acidity

Acid or neutral

Moisture

Normal or wet

Size

2 m tall, 0.6 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Ornamental grasses: Fine stems and plumes are a soft counterpoint to the bold flowers.
• Purple coneflower: Purple-pink flowers in the same sun, a lovely contrast with the yellow.
• Steppe sage: Blue-purple spikes at the base hide the bare stems.
• Buddleja: A tall backdrop that flowers at the same time and attracts butterflies.

Giant coneflower: when and how to plant it?

Plant in March–May and September.

1. Plant in March–May or in September, when the soil is neither frozen nor waterlogged.
2. Dig a hole twice as wide as the root ball and mix in some compost.
3. Set the plant at the same depth as in its pot, with the rosette just above the soil; do not bury the rosette.
4. Leave 50–60 cm between plants, ideally in groups of three.
5. Water in at once and spread mulch around the plant, keeping the rosette itself clear.

Care

Water

In the first year, water weekly in dry weather. Later, water generously at the base during long dry spells.

Feeding

A spadeful of compost in spring. Too much nitrogen gives tall, floppy stems.

Mulching

A layer of leaf mould in spring keeps the soil moist; keep the rosette clear.

Support

Usually unnecessary, but in a windy spot the tall stems may appreciate some support.

Seed cones

Leave the cones standing after flowering: they decorate the winter garden and feed birds.

Moving

Best done when young, in spring; old plants cope less well with being moved.

Tip: Leave the seed cones standing over winter: they look good and birds eat the seeds. Protect the young rosette from slugs in spring and do not cover it with mulch.

Giant coneflower: when to prune it?

Pruning months: March.

When: In March, before the new flower stems appear.

How:

• Cut last year’s flower stems and seed cones down to just above the rosette.
• Remove damaged or dead leaves from the rosette by hand.
• If you do not want seedlings, cut off some of the seed cones in autumn.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or early September, carefully lift an older clump and divide it with a sharp spade into pieces with roots and a rosette. Replant at once and water.

Seed

Sow in a tray in spring or autumn; it also self-seeds, and seedlings often flower only after a year or two.

Giant coneflower: how does it get through the winter?

Hardy to −25 °C.

• Hardy down to about −25 °C: no protection is needed in Belgian winters.
• The rosette may stay largely green in a mild winter; do not cover it with thick leaves or mulch, or it will rot.
• Heavy clay that stays wet in winter is risky: improve drainage or work sand into the soil.

Diseases and pests

• Slugs: Slugs and snails love the young rosette in spring. Pick them off in the evening and lay a barrier of coarse sand or crushed shells.
• Rotting rosette: Brown, soft leaves in wet winters. Improve drainage and do not cover the rosette with mulch.
• Powdery mildew: White powder on the leaves in dry, stuffy summers. Give it space, water at the base and cut off affected leaves.
• Flopping stems: In wind and over-rich soil the tall stems bend. A sheltered spot, less fertiliser and support help.

Through the year

• March: Cut old stems down to above the rosette. Plant. Apply compost.
• April: Plant. Watch for slugs.
• May: Plant. Mulch, keeping the rosette clear.
• June: Flower stems rise. Water in dry weather.
• July: Flowering starts. Support if needed.
• August: Full flower. Water in dry weather.
• September: End of flowering. Plant or divide.
• October: Leave the seed cones for the birds.
• December: Rest. The dark cones decorate the garden.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Birds

Berries, seeds or insects as food, or a place to nest.

Did you know?

• The species name maxima means ‘largest’ and refers to the plant’s imposing size.
• The blue-grey foliage is covered with a thin waxy layer, which helps to limit water loss.
• Seed-eating birds such as goldfinches pick at the seed cones of coneflowers in winter.