There’s nothing “minor” about bulbs like alliums.
Dutch growers classify bulbs that aren’t the big three — tulips, daffodils and hyacinths — as “minor” bulbs. Alliums, a humble relative of the onion, can have a major impact in the perennial border. In bloom, these cheerful flowers have been described as confetti, exclamation points, lollipops or firecrackers exploding in early to mid-summer borders.
Fall is the season for planting alliums. With some exceptions, the bulbs are fairly small and easily tucked into the garden in clusters or scattered here and there. Just remember to plant them to a depth 3 times their diameter. You also can plant them when you’re burying other spring-flowering bulbs like tulips or daffodils.
Alliums are perfect for bridging the gap between spring and summer flowers. By happenstance, I have a clump of blue A. caerulem that occasionally bursts into bloom about the time the last of the pink double late-blooming “Angelique” tulips are fading away. The tulips top out at about 18 inches, while the alliums climb to 20 inches tall, and the pink-and-blue effect, however brief, is joyous to behold.
Bulbs are hardy from zones 3 to 9 and have a range of bloom times. They tolerate poor — but not soggy soil. Bulbs will rot if the soil is too moist. They prefer a sunny and well-drained site. It’s the stems, not flowers that have a strong onion aroma when cut or crushed. Rabbits and deer will leave them alone, but pollinators enjoy sipping the nectar.
Alliums look just as pretty in a formal garden as in an informal one. In a modern setting, tall varieties like “Globemaster” take on an architectural appearance, while they look equally at home in the naturalistic garden with ornamental grasses or the garden with bright red poppies, achillea and other perennials.
In addition to all shades of purple, you’ll find varieties in pink, burgundy, yellow, white and blue. The flowers themselves are clusters of individual starry florets.
This year, be sure to include A. “Millenium,” in your plantings. It’s a 2018 perennial plant of the year that forms clumps of strappy leaves and in mid-summer, produces a profusion of 2-inch diameter rosy purple, round clusters.
Here are a few other alliums worth planting:
A. amethystinum “Red Mohican” — Flamboyant burgundy red globes with tiny buds that open to white florets.
A. “Metallic Shine” — Airy, open flower heads with silvery purple florets on a compact plant.
A. “Powder Puff” — A low-growing edge-of-the-border allium with large lavender-purple globes on short stems.
A. “Pink Jewel” — Pink 3-inch-diameter globes.
A. “Spider” — Cross between A. schubertii and A. atropurpeum, airy, star-shaped florets in deep violet.
A. roseum bulbiferum — Two-inch blush-pink globes are long-lasting from 3 to 4 weeks.