Purple-blue pompoms, perfectly spherical and up to 12 inches across, float on tall bare scapes above leaves that yellow and fade. The giant ornamental onion (Allium giganteum) lines the back of a flower bed, fills pots, and cuts well for bouquets; give it high sun and light, free-draining soil at pH 5.5 to 6.5, and blooming is maximised.
| Name | Allium L. |
|---|---|
| Family | Amaryllidaceae |
| Type | bulbous or rhizomatous perennial |
| Exposure | full sun |
| Foliage | deciduous |
| Flowering | spring to autumn depending on species |
– Allium giganteum
Easy to grow, it is perfect in flower beds or in pots and garden boxes to decorate your terrace or balcony.
Allium giganteum is planted in fall more or less 4 to 5 inches (10 to 12 cm) deep in light soil.
A good tip to know how deep to plant it is to multiply the height of the bulb by 3. If it is 2 inches (5 cm) tall, plant 6 inches (15 cm) deep.
Caring for allium is extremely easy, since the needs of this perennial bulb plant are not difficult to meet.
In both pots and in the ground, they will bear nice flowers without asking you to care for them.
Note that allium leaves tend to turn yellow before or after the blooming of the large umbels, and so it helps to plant ground-covering perennials around the giant onion plants, to cover the wilted leaves and only let the flower stem stick out.
As for pot-growing allium, remember to water regularly because water needs are higher due to the fact that potted plants tend to dry off faster.
Ornamental alliums range from waist-high drumsticks to giant globes on bare scapes, and they flower in succession from late spring into late summer. The table below compares the varieties most often found on UK and US bulb shelves, so you can match colour, height and season to the spot you have in mind.
| Variety | Flower colour | Height band | Flowering season | Best use |
|---|---|---|---|---|
| ‘Purple Sensation’ | Deep violet-purple | Tall | Late spring | Mixed borders, cutting |
| ‘Gladiator’ | Lilac-purple | Tall | Late spring | Back of border |
| ‘Globemaster’ | Violet, very large globes | Tall | Late spring to early summer | Focal point, dried heads |
| Drumstick allium | Maroon-red, egg-shaped | Medium | Midsummer | Weaving through grasses and perennials |
| ‘Purple Rain’ | Purple, loose starry heads | Tall | Late spring | Borders, long-lasting heads |
| ‘Mount Everest’ | White | Tall | Late spring | Pale schemes, dark-leaved partners |
| ‘Ivory Queen’ | Pale pink to ivory | Dwarf | Late spring | Front of border, broad grey leaves |
| ‘Millenium’ | Rose-purple | Dwarf | Late summer | Clump-forming edging, bees and butterflies |
| ‘Ambassador’ | Deep purple | Tall | Late spring | Back of border, sturdy stems |
Allium is a perennial that grows quite easily which will produce very beautiful purple blue flowers that can be up to 8 to 12 inches (20 to 30 cm) across.
Native to Europe and Asia, this ornamental onion belongs to the same genus as the following species: edible garlic, onion, shallot, chives and belongs to the same family as leek.
The different Allium varieties all boast superb flowers bunched up in balls and the size and color of this ball depends on the variety.
In flower beds or along edges, and also along a wall or simply plunked in the middle of the yard, the ornamental impact of this plant is guaranteed!
It is also used in flower bouquets, because the foliage and the flowers both can be used to make appealing bouquets.
For the taller species you can stake the stem to keep it from folding under the wind. Nice for this is to use bamboo, it is perfectly suited and actually enhances the visual impact of the plant.
