Ambassador Allium Plant Profile

Big, Showy Flower for Your Spring Bulb Garden

Allium 'Ambassador' in bloom.
David Beaulieu

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 is a type that is valued for being tall and for bearing large, globe-shaped flower heads.

While they are related to such better-known plants as onions and garlic, flowering onions serve ornamental purposes. 'Ambassador' is one of the showiest; it adds great color to the late-spring bulb garden.

Botanical Name Allium 'Ambassador'
Common Name Ambassador allium, Ambassador flowering onion
Plant Type Bulb plant
Mature Size 46 inches tall
Sun Exposure Full sun
Soil Type Friable, evenly moist, and well-drained
Soil pH Slightly acidic to neutral
Bloom Time May to June
Flower Color Light purple
Hardiness Zones 5 to 8
Native Area Northern Hemisphere

Ambassador Allium Care

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 you should plant the bulbs is information that 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 in the bulbs after planting them.

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 plant.

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 the bulbs in spring or fall.

Light

For optimal flowering, grow Ambassador allium in full sun.

Soil

Grow Ambassador allium in well-drained soil. In terms of soil pH, it prefers somewhat acidic ground, but it tolerates a neutral pH.

Water

Keep the soil around your Ambassador allium evenly moist. But, once mature, it is a relatively drought-tolerant perennial.

Fertilizer

Fertilize it with compost.

Is Ambassador Allium Toxic?

Plants in the Allium genus are poisonous to pets. If you have a cat that goes outdoors, for example, erect a fence around the part of the garden where you are growing Ambassador allium so that your cat cannot access the plant. Alliums are poisonous plants for dogs, as well. Pets can become deathly ill from eating the seeds.

What Makes Ambassador Allium Special

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

  • "Umbel"
  • "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 fanning 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).

The 'Ambassador' cultivar stands out in two ways:

  • It bears a big umbel (often 7 inches across) that is perfectly round and densely packed with tiny, star-shaped, light-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 density makes it an impressive sight.
  • It is one of the tallest flowering onions (the tallest examples may stand 46 inches tall). In fact, due to the height of its scape, some refer to it as a "giant" allium. This scape is very sturdy, making it good for floral arrangements.

Grown in USDA zone 5, Ambassador allium will begin blooming the third week in May and continue 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.

The leaves of Ambassador allium are strap-like.

Landscape Uses for Ambassador Allium

Juxtapose Ambassador allium with a yellow, late-blooming tulip plant to create a sharp color contrast. It is also a good companion plant for rose bushes.

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.