ALLIUM giganteum. The Giant Onion.

Allium giganteum – The Tallest Ornamental Onion for Statement Summer Borders

Often called The Giant Onion, Allium giganteum is a show-stopping bulbous perennial prized by gardeners for its dramatic height and striking flower heads. This ornamental allium produces dense, star-shaped blooms in a rich lilac-pink shade, held aloft on tall, sturdy stems that are frequently compared to giant lollipops nodding above the border.

As the tallest Allium variety commonly grown in UK gardens, Allium giganteum reaches an impressive 1.5m in height, with flower heads often exceeding 15cm in diameter. Glossy, strap-shaped basal leaves emerge first and die back naturally before the flowers reach their peak, so the blooms take full centre stage.

Key Features

• Dense, globe-shaped flower heads in vivid lilac-pink
• Tall flower stems reaching up to 1.5m
• Large flower heads, often 15cm+ across
• RHS Award of Garden Merit (AGM) winner
• Blooms in early summer, bridging the gap between spring bulbs and summer perennials
• Hardy, low-maintenance bulbous perennial

Why Choose Allium Giganteum for Your Garden?

Originally native to the lower mountain slopes of Central Asia, this giant onion bulb thrives in a sunny position with well-drained soil, making it an excellent, low-fuss addition to UK borders. Its height makes it ideal for planting towards the back of beds, rising elegantly above lower-growing shrubs, perennials and companion bulbs.

Timed to flower just as early spring bulbs fade and before summer perennials take over, Allium giganteum adds structure, colour and an extra dimension to any planting scheme. It has also earned the prestigious RHS Award of Garden Merit, confirming its reliability and garden-worthiness.

How to Plant Allium Giganteum Bulbs

• Plant in autumn, approximately 3 inches (7.5cm) deep
• Choose a sunny site with well-drained soil
• For best visual effect, plant in groups of three or more
• Space bulbs to allow the full 15cm flower heads room to develop
• Pair with our full range of autumn-planted flower bulbs for a continuous season of colour

Product Details

• Pack size: 2 bulbs
• Bulb size: 18–20cm circumference
• Delivery: Free UK delivery, dispatched from late August in time for the new planting season
• Sourcing: All bulbs are sourced from cultivated stocks and visually inspected before packing

Please note: all product images show mature plants in bloom and are for illustration purposes only. Order early to secure your bulbs ahead of the new planting season.