- Common name: Sunflowers
- Botanical name: Helianthus
- Family: Daisy (Asteraceae)
- Type: Annuals and perennials
- Flowering period: July to October
- Height: 50cm to 4m (20in to 13ft)
- Aspect: Full sun
- Soil: Rich, well-drained, retentive
- Hardiness: H4 to H5
- Difficulty: Easy to average
Solar-powered sun worshippers, sunflowers (Helianthus) bask in the warmest patch of the garden, soaring higher and higher towards the daystar on long legs. The flowers they produce are shaped like a child’s drawing of the sun and blaze in fire shades of yellow, amber, and red. And we relish this colour when they bloom late in the season, providing much-needed cheer when the autumn mists set in.
The annual sunflower, Helianthus annuus, is native to Mexico and the southwest states of the US, including California. It has been used as a food crop for centuries and still is today, primarily for cooking oil, livestock food, and bird feed. One of the biggest suppliers is Ukraine, which has meant a big drop in supply and a surge in costs, as anyone who feeds the birds will know; sunflower hearts are favoured by many feathered garden visitors, especially blue tits, siskins, and goldfinches. Another option is to provide for them by growing your own sunflowers – by late autumn and early winter, the enormous spent dinner-plate flowerheads are a bounty for the birds, who pluck out the seeds. As long as the sunflower is not a pollen-free floristry variety, it will also provide food for bees when in bloom.
Unlike us, bees and birds are capable of reaching the tallest sunflowers, which can tower to incredible heights, over 4-metres. But, of course, not everyone would want to reach them: sunflowers tend to incite a love or loathe reaction. While some people can’t bear them, others – of all ages – can’t get enough of them, especially the giants, and sunflower competitions are still held up and down the country locally and nationally, including one this year by Age UK. The world record for height is 9.17 metres (30.1 feet) tall, while the record for flowerhead size is 82 centimetres (32.25 inches) wide. Of course, the champion growers refuse to share their cultivation secrets, but the key ingredients are reputed to be manure and seaweed.
Dedicated sunflower haters can often be mollified by the sight of the nontraditional annuals, which are not as tall and bloom in cream, copper, raspberry, and claret shades. But the best way to convert a sunflower sneerer is to show them one of the perennial strains – these look so different to the annuals and are so rarely grown that they are usually mistaken for rudbeckias. You might also point out to them that the modern-day intolerance of the poor old sunflower does not echo back in time: for this flower was viewed as lucky and sacred by American Indians and by the Aztecs and Otomis of Mexico, who saw it as a symbol of the sun, and, after the sunflower arrived in Europe during the 16th century, it was revered here for supposedly being heliotropic (physically moving to follow the course of the sun); although, in truth, the flowers usually remain facing east throughout the day.
Van Gogh certainly never turned his nose up at the golden sunflower varieties and painted them 11 times. It is thought that his lust for them was helped by taking the drug digitalis (from foxgloves) for his epilepsy, since it can create the optical illusion of everything having a mesmerising yellow hue and being haloed. To those of us who agree with Van Gogh that the sunflower is friend not foe, their late-summer blooming is always a joy. There are so many reasons to love them. Having big seeds that are easy for small fingers to handle and growing into friendly-looking giants, they are the best plants to get children involved in the garden; no flower can beat them for height, character, and madcap cheer; they are great for wildlife; and, of course, there is the unquenchable annual thrill of irritating the sunflower naysayers.
Which sunflowers to grow
Beyond the ubiquitous annual yellow sunflowers that people tend to love or hate, there is a huge range of lesser-known varieties. These produce big daisy flowers in a spectrum of desirable, stylish colours and tend to be a lot more compact, reaching around 1.5 metres and therefore ideal for the back of the border. ‘Velvet Queen’ is a deep coppery red, ‘Earthwalker’ is terracotta bronze, ‘Valentine’ is pale ice-cream yellow, and ‘Ruby Eclipse’ blushes raspberry with coffee-cream tips. Slightly shorter, the lovely primrose ‘Vanilla Ice’ (1.2 metres) and pink-cream ‘Ms Mars’ (75 centimetres) can be grown in the middle of the border or in pots. Anyone growing with children should opt for the characterful dwarf yellow ‘Little Dorrit’, which looks like a plant Alice might have come across in Wonderland.
Although they are not widely grown, perennial sunflowers make excellent back-of-border plants that are easy to grow and produce a cloud of much-needed colour at the end of the season. The one you’re most likely to find in the garden centre is ‘Lemon Queen’, which produces a superb mass of soft-yellow daisies throughout August, September, and October. Harder to find, but worth seeking out are ‘Monarch’ (semi-double flowers), ‘Capenoch Star’ (anemone-like flowers), or ‘Soleil D’Or’ (dahlia-like flowers): all three are a rich, sunny shade of gold that lifts the autumn scene. Last but not least, the weird and wonderful Helianthus salicifolius is only suitable for large or informal gardens, since its barmy plumes of willow-like foliage can tower to 3 metres.
Where to grow sunflowers
Sunflowers are long-legged sun worshippers, so a sheltered site in full sun is vital. Because they are greedy, thirsty plants, the soil should be well-drained, retentive, and fertile or enriched to be so by forking in organic matter; most sunflowers require a sturdy support, such as a small tree stake, so the soil needs to be deep and loosened if it is compacted; a neutral to alkaline soil is also important.
How to plant sunflowers
Sow annual varieties under cover (for example, in a greenhouse or cold frame) in early spring, then transplant seedlings into individual pots. If you intend to grow the plant for cut flowers, pinch out the tip when the plants are around 20cm. When the weather warms in mid to late spring, sunflowers can be sown direct and home-grown (or shop-bought) plants (that are ideally around 30cm) can be planted outside in beds that have first been generously enriched with organic matter (such as peat-free compost or well-rotted manure). It’s best to sow or plant in clumps, as sunflowers look better in groups rather than grown individually. After sowing or planting, lay down your preferred slug arsenal (such as whelk shells or Nemaslug).
Plant perennial forms in spring or early summer in beds that have been enriched with organic matter (such as peat-free compost or well-rotted manure) and protect the plants from slugs. Plant them alongside grasses and other late bloomers, such as red-hot pokers, asters, Mexican sunflowers (Tithonia), and heleniums.
How to care for sunflowers
Sunflowers need watering well and regularly, especially when they are young or when there is a period of heat or drought.
Provide a sturdy support for taller sunflower varieties, such as a tree stake.
Leave them on the annual plants to provide food for garden birds (including finches and tits) in the autumn.
Perennials can be cut right back after flowering in the autumn or, even better, in early spring, so that the stems can provide a habitat for insects over winter.
Lift and divide perennials every 3 to 5 years in spring or autumn, in order to boost flower power and health and to create new plants.
How to grow giant sunflowers
If your aim is to rear the biggest sunflower you can, start by sowing a competition variety. ‘Russian Giant’ and ‘Giraffe’ are very tall, capable of 4 metres or more, and ‘Mongolian Giant’ is one of the best for huge flowerheads, sometimes swelling to 45 centimetres (18 inches) across. Don’t pinch out the tips of the seedlings. Plant in soil that has been generously enriched with a blend of organic matter (such as well-rotted manure or peat-free compost), fertiliser (such as Osmocote), and liquid seaweed. The sunflower will require a very strong, tall support, such as a sizeable tree stake.
How to grow Mexican sunflowers
Commonly known as the Mexican sunflower or the red sunflower, Tithonia rotundifolia, is not closely related to the common sunflower (Helianthus annuus), but belongs to the same plant family (Asteraceae). It produces fabulous glossy orange or golden daisies that lure butterflies from July into October and can be cut for the vase. Sow under cover (use a propagator in a cold greenhouse) in early spring, or sow direct in late spring. Like regular sunflowers, Tithonia enjoy well-drained soil and full sun and usually need staking, but they don’t like as rich a soil as Helianthus. ‘Torch’ is a tall orange cultivar, and ‘Fiesta del Sol’ is more compact.
