

Allium giganteum - Giant Allium
Allium giganteum - Giant Allium
Allium giganteum
Giant Onion, Giant Allium
This plant carries a 6 months recovery warranty
More information
We guarantee the quality of our plants for a full growing cycle, and will replace at our expense any plant that fails to recover under normal climatic and planting conditions.
Seed-only orders are dispatched by sealed envelope. The delivery charge for seed-only orders is €3.90.
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Description
Allium giganteum, also known as giant ornamental garlic, is undoubtedly one of the largest species among ornamental garlics. This bulbous plant stands at a height of 1.50m (5ft) and has spherical umbels composed of tiny star-shaped flowers, ranging from pale lilac to deep purple-pink. The rosette of ribbon-like grey-green leaves is aromatic, and all parts of the plant release an onion scent when crushed. It should be grown in sunny locations to brighten up flower beds and rockeries, in light but moist soil.
Allium giganteum is a perennial bulbous plant native to Iran and southern Central Asia, belonging to the family of lilies (alliums). In spring, it forms a basal rosette composed of deciduous grey-green leaves, linear in shape, measuring 35 cm (14in) long and 5 to 10 cm (2 to 4in) wide, which disappear in summer, while sturdy stems emerge from their centre, reaching a height of 1.50m (5ft) and bearing very dense spherical umbels of approximately 15 cm (6in) in diameter. Their colour varies from pale lilac to vibrant purple-pink when fully bloomed.
This is the latest blooming ornamental garlic. Easy to grow, Allium giganteum thrives in any type of well-drained and sunny location. It can be used in flower beds or as a border for pathways, and can also be grown in pots to enjoy its beautiful flowering on a balcony or terrace. Enhance your floral arrangements with its leaves or flowers, or dry them for a unique touch! Plant Allium giganteum in groups of 3 or 5, nestled among your perennials, or combine it with trimmed boxwoods for a spectacular graphic effect. Its stunning inflorescences will also be beautifully complemented by a backdrop of grey foliage shrubs, such as artemisias for example.
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Flowering
Foliage
Plant habit
Botanical data
Allium
giganteum
Amaryllidaceae
Giant Onion, Giant Allium
Cultivar or hybrid
Other Thompson and Morgan seeds
Planting and care
Sow Allium seeds from January to mid-March at 15-20 ° C, on the surface of well-drained, high-quality potting soil. Keep the soil moist but not waterlogged and do not exclude light. Place in a mini-greenhouse or enclose the seed tray inside a polyethylene bag until germination, which usually takes 3 months. If germination does not occur by the end of this period, transfer the container to the refrigerator (not the freezer) at 5 ° C for a period of 3 months. Regularly check if germination is not occurring in the refrigerator and remove the tray as soon as the seeds begin to germinate. Repeat this cycle if germination does not occur to help overcome any seed dormancy; germination is often erratic, sometimes taking 30 to 365 days to occur.
When the seedlings are large enough to handle, transplant and grow them in cooler conditions until the young plants are large enough to be planted outdoors. Place in a cold frame and plant outside the following spring, with the plants spaced 30cm (12in) apart, in well-drained, sandy or light soil, preferably in full sun. Plant them near other plants whose foliage will cover the bare stems of the ornamental garlic in summer.
Sowing period
Intended location
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Hardiness is the lowest winter temperature a plant can endure without suffering serious damage or even dying. However, hardiness is affected by location (a sheltered area, such as a patio), protection (winter cover) and soil type (hardiness is improved by well-drained soil).

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The flowering period indicated on our website applies to countries and regions located in USDA zone 8 (France, the United Kingdom, Ireland, the Netherlands, etc.)
It will vary according to where you live:
- In zones 9 to 10 (Italy, Spain, Greece, etc.), flowering will occur about 2 to 4 weeks earlier.
- In zones 6 to 7 (Germany, Poland, Slovenia, and lower mountainous regions), flowering will be delayed by 2 to 3 weeks.
- In zone 5 (Central Europe, Scandinavia), blooming will be delayed by 3 to 5 weeks.
In temperate climates, pruning of spring-flowering shrubs (forsythia, spireas, etc.) should be done just after flowering.
Pruning of summer-flowering shrubs (Indian Lilac, Perovskia, etc.) can be done in winter or spring.
In cold regions as well as with frost-sensitive plants, avoid pruning too early when severe frosts may still occur.
The planting period indicated on our website applies to countries and regions located in USDA zone 8 (France, United Kingdom, Ireland, Netherlands).
It will vary according to where you live:
- In Mediterranean zones (Marseille, Madrid, Milan, etc.), autumn and winter are the best planting periods.
- In continental zones (Strasbourg, Munich, Vienna, etc.), delay planting by 2 to 3 weeks in spring and bring it forward by 2 to 4 weeks in autumn.
- In mountainous regions (the Alps, Pyrenees, Carpathians, etc.), it is best to plant in late spring (May-June) or late summer (August-September).
The harvesting period indicated on our website applies to countries and regions in USDA zone 8 (France, England, Ireland, the Netherlands).
In colder areas (Scandinavia, Poland, Austria...) fruit and vegetable harvests are likely to be delayed by 3-4 weeks.
In warmer areas (Italy, Spain, Greece, etc.), harvesting will probably take place earlier, depending on weather conditions.
The sowing periods indicated on our website apply to countries and regions within USDA Zone 8 (France, UK, Ireland, Netherlands).
In colder areas (Scandinavia, Poland, Austria...), delay any outdoor sowing by 3-4 weeks, or sow under glass.
In warmer climes (Italy, Spain, Greece, etc.), bring outdoor sowing forward by a few weeks.