Allium 'Globemaster' - Spectacular Giant Ornamental Onion
Overview
Allium 'Globemaster' is a show-stopping ornamental onion that creates magnificent purple spheres in late spring and early summer. This award-winning cultivar produces some of the largest flower heads in the allium family, making it an unforgettable addition to borders, cottage gardens, and contemporary planting schemes. The dramatic globe-shaped blooms can reach up to 20cm (8 inches) in diameter and sit atop sturdy stems, creating a stunning architectural feature that attracts pollinators and admiring glances in equal measure.
Key Features
Flower Colour: Rich violet-purple
Flowering Period: Late May to July
Height: 80-100cm (31-39 inches)
Spread: 20-30cm (8-12 inches)
Hardiness: Fully hardy (RHS H7)
Aspect: Full sun
Soil Type: Well-drained, fertile soil
Growing Conditions
'Globemaster' thrives in a sunny position with well-drained soil. Like most alliums, it detests sitting in waterlogged conditions, particularly during winter dormancy. The bulbs perform best in fertile soil that has been enriched with organic matter, though they're remarkably tolerant once established. This cultivar is suitable for growing in borders, gravel gardens, or large containers, and is fully hardy throughout the UK, withstanding temperatures down to -20°C.
Planting Guide
Plant bulbs in autumn (September to November) at a depth of approximately 15cm (6 inches) and space them 20-25cm (8-10 inches) apart. Position bulbs with the pointed end facing upwards. For maximum impact, plant in groups of at least five bulbs, or combine with other alliums of varying heights for an extended display. 'Globemaster' works beautifully when planted amongst perennials, as neighbouring plants will helpfully disguise the allium's dying foliage after flowering.
Care and Maintenance
This is a refreshingly low-maintenance plant. Water during prolonged dry spells in spring and apply a balanced fertiliser in early spring to encourage robust flowering. After blooming, allow the foliage to die back naturally—this enables the bulb to store energy for next year's display. The seed heads can be left in place for autumn interest or cut for dried flower arrangements. Every few years, lift and divide congested clumps in autumn to maintain vigour.
Garden Design Ideas
The spherical blooms of 'Globemaster' provide wonderful structure and a striking focal point in mixed borders. They look particularly effective rising above lower-growing perennials such as catmint, hardy geraniums, or silvery artemisia. The purple flowers complement yellow and orange companions beautifully—consider pairing with euphorbias or early daylilies. The architectural quality of the blooms also makes them ideal for contemporary, minimalist planting schemes.
Wildlife Benefits
'Globemaster' is a magnet for bees, butterflies, and other beneficial pollinators. The long-lasting flowers provide an important nectar source during late spring and early summer. As a bonus, deer and rabbits tend to avoid alliums due to their onion scent, making this an excellent choice for rural gardens.
Awards and Recognition
This exceptional cultivar has received the Royal Horticultural Society's Award of Garden Merit (AGM), recognising its outstanding performance, reliability, and availability.
Quick Tips
- Plant in autumn for flowers the following summer
- Excellent as cut flowers—lasting up to two weeks in a vase
- Seed heads provide architectural interest well into autumn
- Ideal for adding height without bulk in mixed plantings
- Virtually pest and disease-free
Buying Bulbs from Jacksons Nurseries
Bulbs are supplied either in pre-packaged retail packs or in some cases they are loosly picked and sent bagged.