Sunflower

Annual

Helianthus annuus

Sunflower

The classic tall annual with huge yellow flower heads in late summer, feeding bees and then birds.

  • Full sun
  • 0.6–3 m (2–10 ft)
  • 30–90 cm (12–35 in)
  • H3 · Zone 9
  • July–September
  • Deciduous

Overview

Common sunflower is a fast-growing annual with rough, heart-shaped leaves and large flower heads of yellow, orange, red or bronze petals around a dark centre from midsummer into autumn. Varieties range from 60 cm (2 ft) bushy, branching types for pots and cutting to single-stemmed giants over 3 m (10 ft).

Sow seeds after the last frost once the soil is warm, or a few weeks earlier in pots under cover, in full sun and fertile, well-drained soil sheltered from wind. Stake tall varieties, water in dry spells and protect seedlings from slugs. Leave the ripe seed heads standing for finches, tits and other birds.

It is frost-tender, killed at about 0°C (32°F), and grown as a summer annual everywhere. It thrives in long, hot summers, from continental to subtropical climates, and tolerates drought once established; in cool, short summers choose early-flowering varieties.

At a Glance

Sun Full sun
Height 0.6–3 m (2–10 ft)
Spread 30–90 cm (12–35 in)
Hardiness H3 · Zone 9
Flowers July–September
Soil Chalk, Clay, Loam, Sand
Moisture Moist well drained
Habit Upright
Water Moderate
Maintenance Easy

Growing Conditions

Min. Temperature -2°C (28°F)
pH Range 6–7.5
Fertility Fertile
Drainage Free Draining

Aspect Suitability

  • South-facing
  • West-facing

Site Tolerance

  • Drought

Soil Tolerance

  • Clay
  • Chalk
  • Sandy
  • Loam
  • Neutral pH
  • Alkaline

Foliage

Persistence Deciduous
Colour Green
Leaf shape / texture cordate

Foliage interest: June–September

Seasonal Timeline

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Flowering
Foliage
Propagate
  • Flowering Jul Aug Sep
  • Foliage Jun Jul Aug Sep
  • Propagate Apr May

How to propagate

One way to grow more Sunflower:

From seed Apr–May Easy
  • Sow about 15 mm deep
  • Germinates best at about 20°C
  • Comes up in 5–14 days
  • Pot on about 4 weeks after sowing
  • Direct sow once soil is above about 10°C (50°F).

You'll need: Small pots or modules, multipurpose compost

  1. Sow one seed per pot, 1–2 cm deep.
  2. Keep at about 18–20°C (64–68°F).
  3. Grow on in good light.
  4. Plant out after the last frost, 45 cm (18 in) apart.
How long
10 minutes
It's worked when
high
Then
Stake tall varieties early.

Sow 1–2 cm (½–¾ in) deep where it is to flower after the last frost, or in pots a few weeks earlier.

Maintenance Calendar

  • Apr Sow seed in pots under cover
  • May Sow outdoors after the last frost
  • May Protect seedlings from slugs and snails
  • Jun Stake tall varieties against wind
  • Jul Water deeply in dry spells
  • Sep Leave ripe seed heads for birds or hang them up to dry

Garden Design

Works well in: Cottage, Prairie / Meadow, Wildlife-friendly

Tall varieties for screens and children’s gardens; branching types for cutting.

Companion planting: Cut flowers, Cosmos, Dahlias, Vegetable garden edges

Wildlife Value

  • Bees
  • Butterflies
  • Other pollinators
  • Birds
  • Food source
  • RHS Plants for Pollinators
  • Food

Food for birds: September–November

Safety

Not known to be toxic. Can self-seed and become weedy in warm climates.