Helianthus subrhomboideus — Bushy, Clump forming

Overview

Helianthus subrhomboideus is a bushy, clump forming annual biennial in the genus Helianthus, part of the Asteraceae family, with deciduous foliage. Helianthus subrhomboideus grows best in full sun, and tolerates most soils and any pH. Its UK hardiness is rated H2. Suggested uses include city and courtyard gardens, wildlife gardens, cottage and informal garden and patio and container plants.

About

Helianthus pauciflorus, called the stiff sunflower, is a North American plant species in the family Asteraceae. It is widespread across the Great Plains, the Rocky Mountains, and the Great Lakes region, and naturalized in scattered locations in the eastern United States and in much of southern Canada (from Alberta to Nova Scotia). Stiff sunflower is a perennial herb 50–200 cm (1 ft 8 in – 6 ft 7 in) tall, spreading by means of underground rhizomes. Most of the leaves are attached near the bottom of the stem. It is native to NO. In the garden it prefers full sun and most soil types. In UK gardens it is tender and needs frost-free protection over winter (RHS H2). Suggested uses include city and courtyard gardens, wildlife gardens, cottage and informal garden and patio and container plants. It tolerates soil of any pH, moist but well-drained conditions and south-facing and west-facing aspects.

Wikipedia contributors, CC BY-SA 4.0 — Helianthus pauciflorus

Growing conditions

Best soil and position for Helianthus

Sunlight: Full sun
Soil type: Chalk, Loam, Sand
Soil pH: Acid, Alkaline, Neutral
Soil moisture: Moist but well-drained
Aspect: South-facing, West-facing
Exposure: Sheltered
UK hardiness: H2

Plant details

Helianthus subrhomboideus size, habit and characteristics

Plant type: Annual Biennial
Habit: Bushy, Clump forming
Foliage: Deciduous
Suggested uses: City and courtyard gardens, Wildlife gardens, Cottage and informal garden, Patio and container plants

Care notes

Pruning and caring for Helianthus subrhomboideus

Propagation: Propagate by seed or division. Divide established clumps every 2-4 years to both increase plants and retain vigour. See sowing seeds indoors for further advice
Pest resistance: May be susceptible to slugs and snails
Disease resistance: May be susceptible to powdery mildews and sclerotinia diseases

Frequently asked questions

Where is the best place to plant Helianthus subrhomboideus?

Helianthus subrhomboideus prefers full sun. It suits sheltered positions.

What soil does Helianthus subrhomboideus need?

Helianthus subrhomboideus is adaptable and grows happily in most soil types, including chalk, loam and sand. It is happy in soil of any pH. Aim for soil that stays moist but well-drained.

Is Helianthus subrhomboideus hardy in the UK?

Helianthus subrhomboideus has an RHS hardiness rating of H2, meaning it is tender, tolerating 1–5°C, and needs frost-free protection over winter.

How do I propagate Helianthus subrhomboideus?

Propagate by seed or division. Divide established clumps every 2-4 years to both increase plants and retain vigour. See sowing seeds indoors for further advice.

More in the Helianthus genus

Browse all Helianthus →