How to Grow Allium Globemaster Plants in your Garden

Gardener's HQ Guide to Growing Ornamental Onion

Allium Globemaster, or Ornamental onion, has showy, deep lavender, ball-shaped blooms.

A member of the amaryllis family (Amaryllidaceae), this low-maintenance perennial grows from bulbs and will provide years of pleasure.

Hardy in USDA Zones 5 to 8, Allium Globemaster reaches a height of 1.5-2.5 feet (45 to 7 cm) and produces giant balls of colourful flowers in spring.

It is a great wildlife garden plant as ornamental blooms rise up on stout stems to attract butterflies once the greyish green leaves begin to wither in mid-spring.

Globemaster Alliums photograph by Kim Carpenter.

Globemaster's flower heads may reach as much as 6-10 inches (15 to 20 cm) in diameter, making it a striking accent plant. These impressive blooms are long lasting and created from individual florets in the shape of stars.

Following blooming, flower heads dry and continue to be attractive well into the summer months.

Placing them behind plants with heavy foliage such as Peonies or Iris will produce a lovely scene.

The flower heads are also good for drying. Many gardeners immensely enjoy Allium Globemaster as a naturalized flower.

Gardener's HQ Guide to Growing Ornamental onion

This lovely plant likes full sun but partial shade in the afternoon is a bonus on hot summer days.

It prefers a dry to medium moisture well-drained soil, and will tolerate a wide range of soil types and pH acidities. If your soil is clay, sand may be added to improve drainage.

Ornamental Onion Globemaster does not produce seeds. It is best to plant new bulbs in autumn /fall at 4-6 inches (10 to 15 cm) deep or at three times the diameter of the bulb.

Space Allium Globemaster at about 12 inches (30 cm) apart.

If you require further plants then dig bulbs of established plants to divide and replant in late summer or early fall, be sure to wait until the foliage has died down.

Common Questions

How many members does the Allium genus have?

The Allium genus is large, with around 800 species, which includes onions, garlic, leeks, chives, and ornamental varieties.

Do members of Allium make a good garden or landscaping plant?

Absolutely, many Allium species are excellent in the garden, particularly the ornamental varieties which produce vibrant, globe-shaped flower clusters.

Which Allium species are most frequently grown by gardeners?

Commonly grown species include Allium giganteum (Giant Allium), Allium hollandicum 'Purple Sensation' and Allium schoenoprasum (Chives).

Are members of the Allium plant genus fragrant?

Many Allium species have a distinctive onion or garlic scent when their leaves are crushed. The flowers themselves are not typically fragrant.

What is the perfect location to grow Allium?

Allium prefers full sun and well-drained soil. They are drought tolerant and work well in many types of gardens, from vegetable to flower beds.

Is Allium invasive in the USA, if so in which states?

Some species, such as Allium vineale (Wild Garlic), can be invasive in some regions of the USA. Please check with local regulations.

How do I remove Allium plants from my garden?

Allium can be removed by digging out the bulbs. Be sure to remove all the bulbils to prevent future growth.

Summary

The Allium genus, part of the Amaryllidaceae family, includes about 800 species of bulbous perennials. Known as ornamental onions, these plants are grown for their spherical clusters of flowers in various shades of purple, pink, yellow, and white. They are also known for their distinctive onion-like scent when crushed.

Allium plants prefer full sun and well-drained soil. They are highly adaptable and can tolerate poor soil conditions. These plants are perfect for adding height and structure to a flower border or bed. In addition, they are deer resistant and attract bees and butterflies, making them beneficial for pollinator gardens.

I hope that you enjoyed this guide on how to grow Allium Globemaster. You may also enjoy the following growing guides: How to grow Allium aflatunense and Allium moly.