Towers of colour

Sow or plant mulleins in spring for glorious spires of summer flowers that add vertical accents to the border and provide nectar for bees

- Hazel Sillver

Spires of verbascum, such as 'Gainsborough' and 'Cotswold Queen', add a touch of drama to summer borders

WHEN tall mulleins (verbascums) are at their best in summer, they form incredible spires of yellow. Resembling huge candelabras of flowers, these architectural biennials produce vertical accents in the border. Anyone lucky enough to have visited the gardens in July or August at Great Dixter, East Sussex, or Beth Chatto and RHS Hyde Hall in Essex, will be familiar with these dazzling giants.

"We have Verbascum bombyciferum and V. olympicum in the Dry Garden,' says lan Bull, garden manager at RHS Hyde Hall. "Both have beautiful, large, grey, basal leaves that are woolly and hairy. They throw up huge candle-like flowering spikes to 6ft (1.8m) tall, bearing golden-yellow flowers. They give wonderful height and vertical interest, and the bright-yellow flowers look fantastic against a clear-blue sky."

Tall and slender

Although very tall, these biennial verbascums are slender and can be grown anywhere in the border because they don't obscure the plants behind. At Hyde Hall, they bloom close to the paths among of sea of orange California poppies, as well as in the middle and at the back of borders, towering above other drought-tolerant plants.

"Originating from Greece and Turkey, they love an open, sunny site," adds lan. "They dislike winter wet, so the soil must be free draining. They don't need any support, but if the soil is fertile they may put on more growth and not support themselves so well, as they are used to growing in poor, dry, stony soil."

Biennial yellow Verbascum olympicum reliably self-seeds

Self-seeders