Ambassador Allium: Tall Flowering Onion With Big Bloom

Diplomatic Mission: to Bring Color to Your Late-Spring Yard

My image shows Allium 'Ambassador,
Allium 'Ambassador' is tall and bears a huge flower. David Beaulieu

What Is Ambassador Allium?

Allium 'Ambassador' is the botanical name for this plant. It is commonly referred to by using its cultivar name, Ambassador plus "allium" (with a small A and no italics to indicate that the genus name is being treated as a common name). It is classified as an herbaceous perennial. Ambassador allium is also considered a spring bulb plant.

Plant Attributes

There are many types of alliums (or "flowering onions," as they are sometimes called), which come in various heights and with flower heads of various sizes.

 

Ambassador allium stands out in two ways:

  1. It bears a big flower head (my biggest was 7 inches across) that is perfectly round and densely packed with tiny, purple flowers. While not the biggest of flower heads among the flowering onions (that of Allium schubertii, for example, is bigger), its size combined with its shape and density makes it an impressive sight.
  2. It is one of the tallest flowering onions (my tallest stood 46 inches tall). In fact, some refer to it as a "giant" allium.

Its flower heads take the form of "umbels" (see below); the tiny individual flowers are star-shaped and light purple in color. Mine (growing in USDA zone 5) began blooming the third week in May and continued blooming until the second week in June. The plant becomes dormant in summer. Even after flowering has ended, an attractive dried seed head remains behind to offer visual interest in early summer.

Leaves are strap-like, and the flower stalks, or "scapes" (see below) are tall and extremely sturdy.

Planting Tips, Growing Conditions, Care for Ambassador Allium

Ambassador allium is listed for planting zones 5-8. Plant spring-flowering bulbs such as alliums in fall. The colder your climate, the earlier in autumn you should plant them. Thus gardeners living in hardiness zone 5 should plant in October, while, at the opposite end of the spectrum, you should wait until December to plant the bulbs if you live in zone 8.

How deep should you plant the bulbs? That information is usually provided on the packaging. But if it is not, there is a rule of thumb to remember. Measure the diameter of the bulb and multiply that number by 3. That is your planting depth. Water after planting.

Grow Ambassador allium in a well-drained soil in full sun. Fertilize it with compost. In terms of soil pH, it prefers somewhat acidic ground. It is a relatively drought-tolerant perennial.

You may have to kill slugs and snails to grow Ambassador allium successfully. Leaf miners can also be a problem. But unlike with crocus bulbs, for example, you will not have to worry about rodents. It is also a deer-resistant perennial. While Bambi and Mickey have the good sense to stay away from it, you will have to take precautions to make sure that your pets keep their distance. Alliums are poisonous plants for dogs, and in my article on Schubert's flowering onion I relate a story about how the cat of a certain garden writer became deathly ill eating allium seeds.

As always with spring bulb plants, leave the foliage alone after blooming is finished. No matter how ratty it looks, resist the temptation to cut it off. It is better for the plant's nutrition to let it die back naturally.

Until it does so, furnish it with water during dry spells.

To propagate, divide in spring or fall.

Learning the Lingo

You will hear some specialized terms when reading about flowering onions (although they are not unique to the Allium genus). You encountered two of them above:

  1. "Umbel"
  2. "Scape"

According to etymonline.com, "umbel" and "umbrella" ultimately derive from the same Latin word. This fact makes it easier for beginners to remember that an umbel is a flower head composed of numerous short flower stalks that fan out from a central point -- rather like the ribs of an umbrella.

Meanwhile, a "scape" is a long, bare stalk that supports a flower (as opposed to a flower stalk that bears leaves somewhere between the ground and the flower).

Uses in Landscaping for Ambassador Allium:

  1. Juxtapose with a yellow, late-blooming tulip plant to create a sharp color contrast
  1. Use it as a companion plant for rose bushes
  2. Its tall stature makes it a logical choice for insertion into the back row of a flower border. Such placement offers a bonus: the unsightly leaves of early summer will be hidden, as will be the "hole" left behind by the time it becomes dormant in mid-summer.

Learn about other ornamental onions with purple flowers here.