False sunflower

Sun

Full sun is best; tolerates light partial shade but flowers less and may lean.

Water

Moderate; water regularly while establishing, then during prolonged dry spells. Established plants tolerate some drought but flower better with consistent moisture.

Soil

Average, well-drained soil, including clay that does not remain waterlogged. Avoid excessive fertility, which encourages floppy growth.

Height

3-6 ft (0.9-1.8 m)

Spread

2-3 ft (0.6-0.9 m)

Flowers

Summer to early autumn; golden-yellow rays around yellow to brownish-yellow centres.

Foliage

Opposite pairs of green, pointed, toothed leaves; leaf surfaces range from fairly smooth to rough and hairy.

Growth

Moderate to fast; forms a substantial clump within two to three growing seasons.

Care needed

Low

• Water newly planted clumps deeply whenever the root zone begins to dry.
• Apply a thin layer of compost in spring; avoid high-nitrogen fertilisers.
• Mulch around plants to conserve moisture, keeping mulch away from the crowns.
• Support tall plants early if the site is exposed or partly shaded.
• Divide congested clumps in spring every three to four years if flowering declines.

Pruning. Remove spent flower heads to prolong the display and limit self-seeding, or leave some for birds. Cut dead stems close to ground level in late winter or early spring before new shoots grow.

Early spring

Cut down old stems before new growth develops.

Spring

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

Late spring

Install discreet supports around tall clumps before stems become heavy.

Summer

Water during prolonged dry weather and remove faded flowers if you want continued flowering rather than seed.

Autumn

Leave some seed heads for birds; remove unwanted seedlings while small.

Winter

Leave sound stems standing for wildlife and avoid disturbing waterlogged soil around the crowns.

• Plant in groups through the middle or back of a sunny mixed border for a long band of yellow.
• Combine with ornamental grasses and purple coneflowers in prairie-style planting.
• Use beside purple or blue late-summer flowers, such as asters and Russian sage, for colour contrast.
• Include in a sunny wildlife border where insects can reach the open flower centres.

Garden styles it suits: Cottage garden, Native meadow, New perennial (prairie), Pollinator garden, Hot border and Midwest prairie.

Plant it with: Purple coneflower, Switchgrass, Little bluestem, New England aster, Russian sage and Blazing star.

Wildlife: The flowers attract bees, butterflies and other flower-visiting insects. Seed-eating birds may visit mature seed heads, and standing stems provide shelter for small wildlife.

• Powdery mildew can coat leaves in dry weather, especially in crowded planting; improve airflow and water the root zone during drought.
• Aphids may cluster on young shoots; rinse them off with water and allow ladybirds and other predators to work.
• Leaf spots can develop in humid conditions; avoid overhead watering and remove badly affected leaves and fallen debris.
• Stems may flop in shade or rich soil; provide more sun, reduce feeding and support tall clumps early.

Not known to be toxic to cats, dogs, horses or people. No particular poisonous part is established, but species-specific safety information is limited; do not treat the leaves, flowers or seeds as food.

• Black-eyed Susan (Rudbeckia hirta)

  Usually has a prominent dark brown central cone and alternate, often very hairy leaves; false sunflower has opposite leaves and a lower, yellow to brownish-yellow centre.

• Common sunflower (Helianthus annuus)

  An annual that usually has larger flower heads and broad, often heart-shaped leaves, with upper leaves arranged alternately. False sunflower returns from a perennial crown and has opposite leaves.

Heliopsis means sun-like, while helianthoides means resembling Helianthus, the true sunflowers, which also explains the common name false sunflower.

Propagation. Divide established clumps in spring. Sow species seed outdoors in autumn, or give it a cold, moist period before spring sowing; seedlings from named cultivars may differ from the parent. It can self-seed, so remove unwanted seedlings or deadhead before seed ripens.

Accepted botanical name

Heliopsis helianthoides

In the US and Canada

Native in Canada and the lower 48 states.

Native range

Alabama, Arkansas, Colorado, Connecticut, Delaware, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky and Louisiana.

Measured

Average height 118 cm.

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