Allium Schubertii: Ornamental Onion That Looks Like Fireworks

Allium Schubertii -- What's in a Name?

By Sue Broderick for Dabah Landscape Designs

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There are various common names for this plant, but none refer to what is clearly its most striking feature. That is, because the flower head and seed head look like fireworks exploding, if I were to have the honor of naming the plant, I would include "fireworks" in the moniker. Instead, it goes by such common names as:

  • Ornamental onion
  • Flowering onion
  • Tumbleweed onion (see below)
  • Persian onion
  • Schubert's onion
  • Plant taxonomy refers to it as Allium schubertii.  "Onion" appears in the common names because Allium is the genus name for both edible and ornamental onions.

Plant Type:  Allium schubertii is a spring bulb plant. As with other such bulbs, you must remember to plant in fall if you wish to enjoy those delightful blossoms in spring.

Characteristics of Allium Schubertii:  This ornamental onion reaches a height of 18-24 inches, with a width slightly less than that. Foliage is strap-like. The plant blooms in May in my zone 5 landscape, producing pink flowers.

But that only begins to tell the story of this remarkable plant. It's really the shape, size and structure of the flower head, rather than the color that is exceptional. It's possible for a flower head to contain 100 or more blooms. While some of those blooms (say about 50) in the flower head remain close to the center, others blossoms (another 50 or so, in my example) will be found on longer stalks that shoot out to various distances from the center.

This is the reason why the flower head is said to look like fireworks "bursting in air."

But let's talk measurements. One of mine produced a flower head forming a globe 18 inches across. Some of those longer flower stalks I mentioned were 4 inches long, others 9, still others somewhere in between those figures. A seed head succeeds this flower head and will dry of its own accord, leaving you with a highly decorative, straw-colored sphere of great complexity.

The Missouri Botanical Garden notes that a dried seed head will become disengaged from the clump and "tumble along the ground with the wind spreading seed as they go." Thus the origin of one of the common names: "tumbleweed onion." The allusion is, of course, to that classic desert plant, the tumbleweed, forever associated with Westerns. Other than my invented common name for this plant (namely, "fireworks onion"), "tumbleweed onion" is perhaps the most descriptive designation.

Planting Zones for Allium Schubertii:  I can safely recommend growing these bulbs in planting zones 5-8. I have, however, seen them listed as being even cold-hardier than that. A lot will depend on your soil: if you have a heavy soil that retains water in winter, chances of survival are decreased.

According to Anna Pavord's book on flower bulbs, they are indigenous plants in "Palestine, Syria, northern Iran, and western Turkestan." But they may become naturalized plants elsewhere, under the right conditions.

Sun and Soil Requirements:  Think about the regions to which this ornamental onion is native (see above), and that will give you a clue as to the growing conditions it likes: namely, full sun and a well-drained soil. Once established, it is a drought-tolerant perennial. In fact, it needs to be in dry soil during the summer, fall and winter to remain healthy. Planting in a loamy soil enriched with humus may result in superior growth.

Wildlife and Allium Schubertii:  A good plant to attract butterflies, Allium schubertii does not attract wildlife that you probably don't want on your land, namely deer. Like many strong-smelling specimens (remember, it is a type of onion, after all!), it is a deer-resistant plant. So far, so good. The outlook is not so sanguine, however, if you're a pet owner (see below).

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Care:  The leaves of Allium schubertii are not especially attractive -- particularly during and after flowering. But resist the temptation to tidy up by cutting the leaves. Messy as they look, they are serving a purpose, taking in nutrients through photosynthesis. So let the leaves remain standing until they turn completely brown.  Divide in fall.

If you doubt the cold-hardiness of this ornamental onion in your area, mulch it to furnish winter protection.

To fertilize, you can apply compost anytime. Alternatively, you can apply a bulb fertilizer immediately after flowering, as you would with other bulb plants.

Uses in Landscaping and Beyond:   In spring Allium schubertii is spectacular enough to serve as a focal point in a planting bed of small plants. Give it plenty of space, as you do not want the foliage of other plants obscuring your view of it during its peak display time. Consequently, avoid planting it next to large plants which will swallow it up and render it an afterthought in your design -- a landscape design mistake of which I was initially guilty.

As plants that crave sharp drainage, they are useful in rock gardens.

These ornamental onions will also furnish you with good cut flowers, as they are not only stunning but boast a sturdy stem. Even better, enjoy them as dried flowers (the flower heads will dry out without any help from you and hold up quite well); but see below about taking precautions if you own cats.

Ornamental onions (plus the types that we humans eat) are considered poisonous plants for dogs and cats. Our beloved feline got into our display, playfully chewing on the seeds. Persistent vomiting ensued. $1300 later, she pulled through.

How to Start Allium Schubertii From Seed 

Commonly called tumbleweed onion, Allium schubertii is a perennial ornamental favored for its large, frilly flower heads and ease of maintenance. It grows best in U.S. Department of Agriculture plant hardiness zones 5 to 9, where it is often planted in large groups to create a dramatic flower display in late spring. Tumbleweed onions grow from bulbs, which can be divided from an existing plant or started from seed. The seeds germinate reliably under warm, moist conditions, but the resulting seedlings may take up to three years to produce a mature, dividable flower bulb. Start tumbleweed onion seeds approximately eight weeks before the last spring frost.

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  1. Wrap the seeds in a moistened paper towel and place them inside a sealable plastic bag. Chill the seeds in the refrigerator for four weeks, remoistening the paper towel as needed.
  2. Fill a 2 1/2-inch-deep greenhouse tray with seed-starting compost. Drizzle water onto the compost until it feels moderately moist throughout. Allow the excess water to drain off for ten minutes before sowing the seeds.
  3. Sprinkle the seeds on the surface of the moist compost. Try to space them at least one inch apart. Cover the seeds with a scant, 1/16-inch-thick layer of compost. Press the compost with the palm of your hand. Mist it liberally with water.
  4. Place the greenhouse tray on a germination mat inside a cold frame under bright, filtered sunshine. Set the temperature on the germination mat to 70 degrees Fahrenheit. Moisten the compost with a spray bottle whenever the surface is nearly dry. Do not allow the compost to dry out completely.
  5. Lower the nighttime temperature on the germination mat to 50 F after the sprouts emerge, which should take around four weeks. Thin the tumbleweed onion seedlings to one every 2 inches once they reach 1 inch tall.
  6. Remove the germination mat four weeks after the seeds sprout. Crack open the cold frame to increase air circulation around the seedlings. Continue watering them whenever the compost feels mostly dry on the surface. 
  7. Scoop out and transplant the tumbleweed onion seedlings into individual 4-inch pots filled with a mix of 3 parts potting soil and 1 part coarse sand. Grow them under light shade during their first summer outdoors. Provide each plant 1 inch of water weekly.
  8. Transplant the tumbleweed onion plants into a permanent bed in fall, in mid- to late October. Choose a sunny garden bed with loamy or sandy, fast-draining soil. Group the plants together, allowing 10 to 12 inches of space between them.