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A picture of a Giant Allium

Giant Allium

Allium giganteum

Also known as

Ornamental Onion, Giant Onion, Giant flowering onion

Photo by CandideUK (All rights reserved)

Full Sun
Moderate care
Light watering
Frost Hardy

H5

RHS hardiness

-15°C

Minimum temperature

Expected size

Height
Spread

1.5m

Max

50cm

1m

Min

10cm

5 years to reach maturity

Flowering

  • spring
  • summer
  • autumn
  • winter

This plant has no fragrance

More images of Giant Allium

A photo of Giant Allium
A photo of Giant Allium

Giant Allium Overview

A. giganteum is a perennial with spreading, strap-shaped basal leaves which die down followed by dense, globose umbels of purple flowers on tall, slender stems in summer. This is a wildlife plant producing nectar and pollen for insects.

Common problems with Giant Allium

Generally pest free but may be susceptible to Onion white rot and a Downy mildew.

How to propagate Giant Allium

Seed

Sown in containers in a cold frame when just ripe or in the spring. Alternatively, remove offsets in autumn.

Special features of Giant Allium

Attractive flowers

Other uses of Giant Allium

Suited to flower borders and beds, cut flowers, cottage style gardens and informal gardens.