Sunflower

How to recognise it

Habit

Annual with a single thick, straight stem, usually 1.5–3 m tall; branching varieties form a small bush with several smaller flowers.

Leaf

Large, heart-shaped to oval, 10–30 cm, with a long stalk, toothed edge and rough hairs; opposite low down, alternate higher up the stem.

Flower

A flower head 10–30 cm across, even larger in giant varieties: yellow ray petals around a brown to purplish-brown centre of hundreds of florets arranged in spirals. There are also cream, orange and reddish-brown varieties.

Fruit/Seed

Flat, drop-shaped achenes, the ‘seeds’, black, grey or striped, packed in spirals in the centre.

Stem and roots

Thick, rough-haired stem filled with white pith; a deep taproot with many side roots.

Look-alikes

Jerusalem artichoke (Helianthus tuberosus) is a perennial with edible tubers, narrower leaves and much smaller flower heads of 5–10 cm with a yellow centre.

Flowering: July–September · Pruning: November

Why grow it?

• Grows in a single season from a seed into a giant of 2–3 m: ideal for sowing with children.
• Bees, bumblebees and hoverflies collect pollen and nectar from the hundreds of tiny florets in the centre.
• In autumn the ripe seeds feed tits, goldfinches, greenfinches and nuthatches.
• A cheerful summer flower and a sturdy cut flower from July into autumn.
• Edible: roasted seeds are a well-known snack, and sunflower oil is pressed from the seeds.
• Quickly makes a green summer screen along a fence or in the vegetable garden.

Sunflower: where does it grow best?

• In the wild: open, dry plains, roadsides and waste ground in western and central North America.
• Full sun, as much as possible: in shade it leans towards the light and flowers poorly.
• Any ordinary, well-drained garden soil; the richer the soil, the bigger the plant.
• A sheltered spot against a fence or wall stops the tall stems from blowing over.
• Allow 30–45 cm between small varieties and 50–60 cm between giants.

Goes well with

• Nasturtium: Trails at the base and fills the bare soil between the tall stems with orange and yellow.
• Cosmos: Airy pink and white flowers at half height, also loved by bees.
• Cornflower: A blue annual cornfield flower that you can sow in the same weeks.
• Pot marigold: Low orange flowers at the front, edible and long-flowering.
• Pumpkin: Covers the soil between the sunflowers in the vegetable garden.

Sunflower: when and how to plant it?

1. Buy seed from a garden centre or nursery, or use seed you saved yourself; never dig plants up from the wild.
2. Sow from late April into June directly outside, 2–3 cm deep, two seeds per spot. No cold period is needed.
3. Want earlier flowers, or do you have lots of slugs? Sow indoors in pots in April and plant out from mid-May.
4. Thin to the strongest seedling per spot, 30–60 cm apart depending on the variety.
5. Water after sowing and keep the soil moist until the seedlings are up; after that only in dry spells.
6. For tall varieties, put in a sturdy stake straight away, so you do not damage the roots later.

Care

Water

In dry spells, water generously at the base, especially when the flower bud is forming. Better a lot now and then than a little every day.

Feeding

For giant varieties, some compost at sowing time helps. Ordinary garden sunflowers need no extra feeding.

Support

Tie tall plants loosely to a stake: a summer storm can snap heavy stems.

Spent flowers

On branching varieties, cutting them off gives new flowers. On the others, let the heads ripen for the birds.

Saving seed

Want your own seed? Protect the ripening heads from birds with a paper bag or netting and cut them off when the back turns yellow to brown.

Tip: For bees, choose a variety with pollen: some cut-flower varieties are bred pollen-free so they do not leave yellow stains, but they are of no use to bees.

Pruning and mowing

Pruning months: November.

When: No pruning is needed. Clear the dead stems in November, or leave them standing until spring.

How:

• After flowering, let the seed heads ripen on the plant: tits and goldfinches will empty them.
• On branching varieties, cut flowers for the vase regularly during flowering: new ones will follow.
• Cut the dead stems in November or leave them until spring; then put them on a brush pile for insects.
• Do not pull out the roots: they rot down in the soil and loosen it.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

The only way: sow outside from late April to June, or indoors in April. Seed from F1 varieties gives variable plants; seed from ordinary varieties resembles the parents if no other varieties flowered nearby.

Saving your own seed

Let a head ripen fully, dry it upside down in an airy place and rub out the seeds. Store them dry and cool until spring.

Sunflower: how does it get through the winter?

Hardy to 0 °C: protect in harsh winters.

• The sunflower is an annual: the plant dies after the first night frost.
• Leave a few seed heads standing: until well into winter they remain a feeding station for tits, goldfinches and nuthatches.
• The thick dead stems shelter insects; leave them until spring if you do not need the space.
• Fallen seeds sometimes germinate by themselves the following spring.

Diseases and pests

• Slugs: They eat seedlings overnight. Sow indoors first, protect with a collar cut from a plastic bottle, or pick them off in the evening.
• Birds and mice: They peck up or dig out freshly sown seed. Cover the seedbed temporarily with netting or fleece.
• Blowing over: Tall plants snap in storms. Sow in a sheltered spot and tie them to a stake in good time.
• Powdery mildew: White powder on the lower leaves in late summer. Harmless so late in the season; pick off the worst leaves.
• Aphids: On young tips in summer. Ladybirds and parasitic wasps usually clear them up; otherwise spray them off with water.

Through the year

• April: Sow indoors in pots.
• May: Sow outside, or plant out indoor-sown plants after mid-May.
• June: Thin out, put in stakes and protect young plants from slugs.
• July: First flowers. Water in dry spells.
• August: Full flower. Watch the bees and bumblebees on the centre. Cut flowers for the vase.
• September: The seed heads ripen. Leave a few for the birds.
• October: Collect and dry seed. The plant dies after the first night frost.
• November: Cut down dead stems or leave them for insects.
• December: Tits and goldfinches pick the last seeds from the heads.

Did you know?

• Young sunflowers follow the sun from east to west during the day and turn back at night. Mature flowers stay facing east.
• The seeds in the centre are arranged in two sets of spirals, often 34 and 55 or 55 and 89: numbers from the Fibonacci sequence.
• The name Helianthus comes from the Greek helios, sun, and anthos, flower.