Helianthus 'Uniflorus giganteus ' also known as Sunflower 'Giant Single Yellow' is a tall-growing, single stemmed variety of the traditional easy-to-grow sunflower. The blooms have dark centres and attractive bright golden petals, held on tall stems which are capable of growing several metres.
Like most annuals, they are extremely useful in the border, filling gaps between young shrubs and perennials with immediate explosions of colour and height. It is an ideal variety for mass planting or for children to grow. if planted next to a wall or tall cane they can chart its progress as it grows.
Very easily grown, sown early indoors in pots or sown directly outdoors, they can grow to 8ft tall or more in as little as 12 weeks. Fast growing sunflowers, especially the really big cultivars, are always favourites with children. They are fascinated with the large size and bright colours and love the way the flower follows the sun.
All sunflowers make beautiful, long lasting cut flowers. Bees and butterflies frequent the flowers in the summer and in the autumn birds and squirrels will help themselves to the seeds.
This variety was recently featured in the Gardeners' World Sunflower Trial.
Sow indoors in early spring, at 13 to 18°C (55 to 65°F) 4 to 8 weeks before planting outside, alternatively, the seed can also be sown directly where they are to flower in mid to late spring. Beware of slugs when they are still young plants and birds stealing the seeds. For continuity, sow a succession of sunflowers every fortnight for six weeks in the early part of the growing season. In a hot summer, each cycle from sowing to blooming will take about 60 days.
Please remember when positioning your sunflower that, though they track the sun when in the budding stage, a mature sunflower will almost always face to the east.
For early flowers, start indoors as early as February or March, to germinate in about 10 days at 13 to 18°C (55 to 65°F) and plant out in April or May. Use 7.5cm (3in) pots and a good sowing compost. Sow two seeds 25mm (1in) deep per pot. Water and cover with either polythene or bubble plastic to retain the heat, or place pots on a heated bench or in a propagator with the temperature set at 13°C (55°F).
Remove the covers when the leaves appear. Plant seedlings outside when they are large enough to be handled and the root system is well developed. Add garden compost to the soil if it is heavy or infertile.
Plant outside as early as possible to miss heavy frosts, to germinate in about 1 to 3 weeks, in mid-April through mid-May. Sow seed 5cm (2in) deep and spaced 45cm (18in) apart in borders.
Water seedlings regularly and, when growing tall forms, feed sparingly with a liquid fertiliser when 60cm (2ft) high. Over-fertilization can cause stem breakage in the autumn. Avoid splashing water or fertiliser solution on the stems or leaves.
Harvesting Cut Flowers:
For the vase, cut the fresh flowers in the morning just after they open, but wait until the sun has dried the dew. Remove leaves that are low on the stem, leaving just two or three higher up, near the flower's face. Place the flowers in a bucket filled with water, and leave them to stand for several hours in a cool room before placing in a vase.
Use a clean knife, a clean vase and a few drops of bleach in the water to keep it fresh. Change the water every few days. Blooms can last up to a fortnight when kept in water.
Beware of slugs when they are still young plants and birds stealing the seeds.
To dry sunflower seeds, cut the heads off when they begin to yellow at the back and hang them upside down in a dry location away from rodents and birds. Once dry, rub the seeds off and soak overnight in 4 litres 1 gal) of water with 1 cup of salt in it. Dry in a 250°F oven for 4 to 5 hours and store in an airtight container. The black-seeded varieties are mainly for oil and birdseed. The grey and white-striped varieties are for drying and eating which can be eaten raw or roasted.
The Latin name for Sunflower, Helianthus annuus, is taken from the Greek helios, meaning sun, and anthos, meaning flower. The Sunflower originated from South America and represented the sun to worshiping Aztec people; it was brought to Europe in the late sixteenth century.
Today the Sunflower is grown for crops in the Mediterranean, Eastern Europe, Argentina, India and the USA.
Current Sunflower World Records:
There are three Guinness Book categories for giant sunflowers
The Tallest Plant: 776cm (25ft 5½in) tall by M Heijms Netherlands in 1986.
Measure from the ground to the highest petal on the flower.
The Largest Head: 82cm (32¼in) diameter by Emily Martin in Canada 1983.
Measure from petal tip to the opposite side petal tip.
The Most Flowers: 837 flowers on a single plant by Melvin Hemker, USA in 2001.
This is just simply the task of counting all flower heads.
It's a good idea to tag each flower as you count that branch.
- Additional Information
Family Asteraceae Genus Helianthus Species annuus Cultivar Giant Yellow Synonym Uniflorus giganteus Common Name Uniflorus giganteus, Giant Sunflower Hardiness Hardy Annual Flowers Midsummer to Early Autumn Height to 250cm (to 8ft) Spacing 40-50cm (16-20in Position Full Sun to Partial Shade Germination 5 to 21 days