Annual
How to grow sunflowers
Helianthus annuus
Sow sunflowers in pots indoors in April, or straight into the ground in May once frost has passed, in the sunniest spot you have. They are half-hardy annuals that flower from July to September. Slugs decide most failures, so plant out only when seedlings are 15 to 20 cm tall. For height, choose a single-stem giant, give it deep fertile soil, steady water and a stake before it needs one.
- Hardiness
- Half-hardy annual
- Position
- Full sun
- Soil
- Fertile, deep, free-draining
- Ideal pH
- 6.0 to 7.5
- Water
- Moderate to high for giants
- Feeding
- Moderate feeder
Sowing and planting sunflowers
WhenSow Apr indoors or May direct; flowers Jul to Sep
Starting off
Sow direct late Apr to May 2 cm deep, two seeds per station and thin to the strongest, or singly in 9 cm pots indoors in Apr at 18 to 21 °C, where they germinate in 7 to 10 days.
Spacing and planting
Giants such as 'Russian Giant' 45 to 60 cm apart, branching types 30 to 45 cm, dwarf types 20 to 30 cm; sow 2 cm deep. Dwarf varieties suit a 30 cm pot but tall sorts need open ground.
Varieties worth growing
- 'Russian Giant'
- The standard tall sunflower: one stem to 3 m with a single large yellow head. Good for children's competitions and for bird seed.
- 'Mongolian Giant'
- The one to grow for sheer size, capable of 4 m with a head 40 cm across in rich soil with regular water.
- 'Velvet Queen'
- Branching, about 1.5 m, with many dark red-bronze flowers over several weeks. A good cut flower and less of a wind risk than the giants.
- 'Vanilla Ice'
- Branching, with many small pale lemon flowers on slim stems. The best for picking, and it keeps going until autumn if deadheaded.
- 'Teddy Bear'
- Dwarf at 50 to 60 cm with fully double, fluffy golden heads. Made for pots and the front of a border; needs no staking.
Sunflowers month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do.
- February
Nothing to do. Order seed.
- March
Nothing to do until the last days of the month, when a first sowing indoors is possible in good light. Earlier sowings give leggy plants that sit and sulk.
- April
Sow singly in 9 cm pots indoors from mid month at 18 to 21 °C.
- May
Sow direct, 2 cm deep. Harden off and plant out pot-raised seedlings in late May, after the last frost.
- June
Last sowing of branching types in the first half of the month. Stake as stems pass 60 cm. Top-dress giants and water it in.
- July
First flowers. Tie in again at 1.2 m. Water giants deeply twice a week.
- August
Main flowering. Deadhead branching types and cut for the vase in the morning.
- September
Heads ripen. Cut for seed when the back of the head yellows, or leave for the birds.
- October
Leave seed heads standing for finches.
- November
Pull the plants, chop the stems and compost them.
- December
Nothing to do.
Feeding sunflowers
On decent soil a base dressing is all most sunflowers need. Only single-stem giants grown for height or head size repay a second dressing of the same dry fertiliser in June, and feeding stops when the bud shows.
A balanced feed and rich soil for tall, strong stems; giant types appreciate extra potassium.
Feeding plan
April to May, before sowing or planting
100 g/m² raked in. A giant given 50 cm each way covers 0.25 m², so 25 g per station; a branching type at 40 cm (0.16 m²) takes about 15 g.
Giants only, June, five to six weeks after the base dressing
About 100 g/m², the label top-up rate: 25 g scattered round each station (0.25 m²) and watered in. Once. Do not repeat after the flower bud shows.
Branching and cutting types in the ground
Nothing
No feed after the base dressing. Extra nitrogen gives tall, soft plants that flower late and blow over.
Dwarf types in pots, six weeks after potting
2 g per litre of compost, the low end of the label top-dress: about 24 g for a 30 cm pot holding about 12 litres, scattered on the surface and watered in. Once is usually enough; if you repeat it, wait 5 to 6 weeks and stop when the flowers open.
Signs to watch
Lower leaves pale yellow all over while plants stay short
Nitrogen short on thin soil
A light top-dress of the dry feed in the feeding plan, watered in
Older leaves yellow between the veins
Magnesium short
Epsom salts
Huge leafy plants with a small, late head
Too much nitrogen
Stop feeding and give sulphate of potash
Pests, diseases and problems
Seedlings eaten to a bare stalk overnight, slime trails
Slugs and snails; young sunflowers are a favourite
Raise in 9 cm pots and plant out at 15 to 20 cm tall, by which time the stem is tougher. A collar cut from a plastic bottle and nightly torch patrols cover the first fortnight.
Direct-sown seed disappears, or seedlings are pulled up
Mice, squirrels and birds taking the seed
Cover each station with a cloche, or sow in pots indoors and plant out.
Plant wilts suddenly in summer; the stem base is soft and pale, with white fluffy mould and hard black lumps inside
Sclerotinia stem rot, a soil fungus that also attacks beans, lettuce and Jerusalem artichokes
Dig out and bin the plant before the black resting bodies fall into the soil. Do not compost it, and keep sunflowers and other susceptible plants off that spot for several years.
White powdery coating on leaves from August
Powdery mildew at the end of the season, on plants dry at the root
Water deeply once or twice a week. Late mildew does not stop flowering, so tolerate it.
Ripening heads stripped of seed, or turning mouldy in a wet autumn
Finches and tits feeding; grey mould on a wet head
If you want the seed, tie a paper bag or fleece over the head once the petals drop, cut it when the back turns yellow-brown and finish drying indoors. Otherwise leave it for the birds.
Pruning
Pruning and care
Tie tall stems to a 2 m stake as they pass 60 cm and again at 1.2 m, as a loaded head snaps in an Aug gale. Deadhead branching types to keep flowers coming; leave single-stem giants to ripen their head for the birds and pull the whole plant in Nov. An annual, so no winter protection: compost stems after frost.
Good to knowStake tall varieties; sow direct after frost or start in pots. Leave seed heads for the birds.
Growing sunflowers in pots
Dwarf varieties such as 'Teddy Bear' are the ones for pots: one plant in a 30 cm pot, or three in a 40 cm pot, in peat-free multipurpose compost. Sow direct into the pot in May or plant out a pot-raised seedling, and water daily once the plant is in full leaf. Tall sunflowers can be grown in a container of 40 litres or more, but they need watering twice a day in hot weather, a stake tied to something solid, and will not reach the height they would in the ground.
Sunflowers: common questions
When should I sow sunflower seeds in the UK?
Sow indoors in pots from mid April, or outdoors where they are to flower in May once the risk of frost has passed. Seedlings raised indoors are planted out in late May after hardening off. Sowing earlier than late March gains nothing, as the plants become leggy before it is warm enough to plant them.
How do I grow the tallest sunflower?
Choose a giant single-stem variety such as 'Mongolian Giant', sow in mid April, and plant in full sun in deep soil improved with compost. Water deeply twice a week, give one top-dressing of balanced dry fertiliser in June, watered in, and tie the stem to a tall stake as it grows. Never pinch out the tip of a giant.
Do sunflowers come back every year?
No, the common sunflower is an annual that dies with the first frosts. Seed dropped by the birds sometimes germinates the following May, but named varieties are best resown each spring. There are perennial sunflowers, but they are different plants with smaller flowers.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.
- How to grow Helianthus (sunflowers)RHS
- Helianthus annuusRHS
- How to grow sunflowersBBC Gardeners' World