Helianthus atrorubens

RHS Plant Profile

dark red sunflower

Other common names

dark-eye sunflower

Herbaceous Perennial

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A vigorously spreading herbaceous perennial making clumps, to 1.5m tall, with rough, ovate leaves to 30cm long and flower-heads with orange-yellow ray-florets and a purple-red eye

Position

Full sun, Partial shade

Soil Types

Sand, Loam, Clay, Chalk

Max Height

1-1.5 metres

Max Spread

1.5-2.5 metres

Size

Time to Maturity: 2–5 years
Max Spread: 1.5-2.5 metres
Max Height: 1-1.5 metres

Growing Conditions

Sand Loam Clay Chalk

Moisture: Well–drained or Moist but well–drained
pH: Neutral or Alkaline

Position

Full sun Partial shade

Aspect: West–facing or South–facing or North–facing or East–facing
Exposure: Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H7
Drought Resistance: Yes

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Asteraceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Spreading branched, Bushy
Genus: Helianthus can be tall, erect annuals, tuberous or rhizomatous perennials, with coarse simple leaves and large daisy-like flower-heads
Name Status: Correct

How to Grow

Cultivation

Grow in a moderately fertile, humus-rich, moist but well-drained to well-drained, neutral to alkaline soil in full sun. Does best in soils that don't dry out in summer, but will tolerate dry soil once established. Tolerates some shade. May need support. See staking perennials

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

Suggested planting locations and garden types

Cottage and informal garden
Prairie planting
Wildlife gardens
Low Maintenance
Flower borders and beds
Wall side borders
Cut flowers

Pruning

Deadhead to prolong flowering and cut back to ground level as foliage starts to yellow and die back in autumn

Pests

May be susceptible to slugs and snails

Diseases

May be susceptible to Powdery mildews and sclerotinia diseases