Giant coneflower

Sun

Full sun is best; tolerates light shade, but stems may lean and flowering may be reduced.

Water

Prefers consistent moisture, especially while establishing and during spring growth. Established clumps tolerate some drought, but prolonged dryness can brown the lower leaves.

Soil

Average to rich soil that holds moisture but drains freely; tolerates clay if it is not persistently waterlogged.

Height

5-7 ft (1.5-2.1 m)

Spread

2-3 ft (0.6-0.9 m)

Flowers

Early to midsummer, sometimes continuing into late summer; drooping yellow rays surround tall, dark brown cones.

Foliage

Large, smooth, waxy blue-green leaves form a bold basal clump, with relatively few leaves on the flowering stems.

Growth

Moderate; allow several seasons for a substantial clump.

Care needed

Low

• Pollinators
• Deer resistant
• Cold hardy
• Heat tolerant
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   2.6 ft (0.8 m)

3. After 2 years

   4 ft (1.3 m)

4. After 3 years

   6 ft (1.8 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the US

Growth rate

Moderate

• Water deeply during the first growing season and during prolonged dry spells.
• Spread a thin layer of compost around the clump in spring; avoid heavy nitrogen feeding.
• Mulch to conserve moisture, keeping mulch clear of the crown.
• Use discreet supports before flowering if the site is windy or stems begin to lean.
• Divide congested clumps in spring when growth or flowering declines.

Pruning. Leave the seedheads standing through autumn and winter for birds and structure. Cut old flowering stems back near ground level in late winter or early spring, taking care not to damage emerging leaves.

Late winter

Cut down old stems before new growth develops.

Spring

Plant or divide clumps, water thoroughly, and apply compost and mulch.

Late spring

Install supports in exposed positions before flower stems reach full height.

Summer

Water during extended dry weather and check lower leaves for mildew or spotting.

Autumn

Leave mature seedheads for birds; collect some seed if you want to raise more plants.

• Place at the back of a sunny border, leaving its large basal leaves visible between lower plants.
• Combine with switchgrass and other upright grasses for a loose prairie-style planting.
• Repeat small groups through a large border to create a rhythm of tall flower stems and dark seedheads.
• Use beside a pond or in a moist meadow, above the permanently saturated waterline.

Garden styles it suits: Native meadow, New perennial (prairie), Wildlife garden, Pollinator garden, Architectural minimal and Midwest prairie.

Plant it with: Switchgrass, Little bluestem, Purple coneflower, Blazing star, Bee balm and Joe-Pye weed.

Wildlife: Flowers attract bees, butterflies and other pollinating insects. Goldfinches and other seed-eating birds visit ripe seedheads.

• Flopping stems: provide full sun, avoid rich nitrogen feeds, and support plants in windy sites.
• Powdery mildew: allow airflow, water the soil rather than the foliage, and remove badly affected leaves.
• Leaf spots: remove affected debris and avoid overhead watering; established plants usually tolerate minor spotting.
• Crown rot in waterlogged soil: improve drainage or move the plant to a raised position; remove rotting crowns.

Not known to be toxic to people, cats, dogs or horses. Species-specific safety information is limited; no part is intended as food, and handling may irritate sensitive skin.

• Cutleaf coneflower (Rudbeckia laciniata)

  Has deeply divided green leaves and usually greenish-yellow cones, rather than broad, undivided blue-green basal leaves and elongated dark cones.

• Black-eyed Susan (Rudbeckia hirta)

  Usually much shorter, with hairy green leaves and stems and shorter, rounded flower centres.

• Sweet coneflower (Rudbeckia subtomentosa)

  Has leafy, branching stems and often lobed lower leaves, rather than the conspicuous blue-green basal leaves and sparsely leafy stems of giant coneflower.

Rudbeckia honours the Swedish botanists Olof Rudbeck the Elder and Younger, while maxima means largest and refers to the plant's imposing size.

Propagation. Divide established clumps in early spring. Sow ripe seed outdoors in autumn, or give spring-sown seed a cold, moist period to improve germination; seedlings may take more than one season to flower.

Accepted botanical name

Rudbeckia maxima

In the US and Canada

Native in the lower 48 states.

Native range

Arkansas, Louisiana, Oklahoma, South Carolina and Texas.

Measured

Soil pH 4 to 7.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.