Gardening Guides
Central Plains Gardening
Great Design Plant: Ornamental Allium
Lollipop blooms on tall, leafless stems add an architectural element to gardens of all styles
Landscapes on Houzz lately have put onions on my mind — and I'm not thinking about edible gardening. Relative to the edible onion, the ornamental allium has been a longtime cottage garden companion, but it can embellish gardens of all styles and sizes. Bordering on cartoonish, allium's globular blooms add a new shape to the landscape.
One of the tallest of the genus, Allium 'Globemaster' (zones 4 to 9) can grow 3 to 4 feet tall. Lavender clusters 6 to 8 inches bloom in late spring and persist well into summer. Described as one of the easiest alliums to grow, Globemaster is a go-to choice for floral architecture.
Coming in a litte smaller is Allium hollandicum 'Purple Sensation' (zones 4 to 8). Over 2 feet tall, it produces 2- to 4-inch flowers. Along this walk at The New York Botanical Garden, the dark purple flowers of Purple Sensation appear to float above the tops of its foliage, guiding visitors along an ethereal pathway.
The giant onion Allium giganteum 'White Giant' (zones 5 to 9), can grow 5 feet tall. Its bright lilac flowers lighten up the garden, and its height makes it good for background planting.
How to use it. For such a large plant, allium's tall flower stems create the majority of its volume. The architectural stems lead the eye up into the vertical plane while occupying a smaller footprint, making it great for small gardens or other narrow planting areas — borders, containers or planters.
Plant alliums in a single species mass or intermixed with others. Shown here, in the gardens of Edith Wharton's estate, lower growing plants surround the alliums and will conceal their dying foliage once they have finished blooming for the season.
Plant alliums in a single species mass or intermixed with others. Shown here, in the gardens of Edith Wharton's estate, lower growing plants surround the alliums and will conceal their dying foliage once they have finished blooming for the season.
As cut flowers, alliums create quite the statement-making floral arrangement. Whether dried or fresh, they bring a sumptuous piece of the garden inside.
Planting notes. I’ve heard alliums described as the perfect low-maintenance perennial bulb. They're hardy, easy-to-grow, spectacular bloomers that return year after year. Plant bulbs in fall, in well-drained, sandy soil. Amend the soil with organic matter before planting.
Alliums flower in spring and summer. After they have finished flowering, you can cut back on watering — yellowing foliage will be your cue. The foliage will die to the ground in all climates, and you can simply let it be.
Your alliums will continue to bloom in following years. Clumps can be divided once the beds begin to crowd or when you want to spread alliums to other parts of the garden.
More great design flowers:
Canna Lily | Catmint | Golden Creeping Jenny | Pacific Coast Iris | Plumbago
Red Kangaroo Paw | Sally Holmes Rose | Slipper Plant | Snake Flower
Great design trees:
Dove Tree | Bald Cypress | Chinese Witch Hazel | Japanese Maple | Manzanita | Persian Ironwood | Smoke Tree | Texas Mountain Laurel | Tree Aloe
Great design plants:
Euphorbia | Red-Leafed Mukdenia | Blue Chalk Sticks | Hens-and-Chicks | Redtwig Dogwood | Toyon
Great design grasses:
Black Mondo Grass | Cape Rush | Feather Reed Grass | New Zealand Wind Grass
Alliums flower in spring and summer. After they have finished flowering, you can cut back on watering — yellowing foliage will be your cue. The foliage will die to the ground in all climates, and you can simply let it be.
Your alliums will continue to bloom in following years. Clumps can be divided once the beds begin to crowd or when you want to spread alliums to other parts of the garden.
More great design flowers:
Canna Lily | Catmint | Golden Creeping Jenny | Pacific Coast Iris | Plumbago
Red Kangaroo Paw | Sally Holmes Rose | Slipper Plant | Snake Flower
Great design trees:
Dove Tree | Bald Cypress | Chinese Witch Hazel | Japanese Maple | Manzanita | Persian Ironwood | Smoke Tree | Texas Mountain Laurel | Tree Aloe
Great design plants:
Euphorbia | Red-Leafed Mukdenia | Blue Chalk Sticks | Hens-and-Chicks | Redtwig Dogwood | Toyon
Great design grasses:
Black Mondo Grass | Cape Rush | Feather Reed Grass | New Zealand Wind Grass
Common names: Allium, ornamental onion
USDA zones: 3 to 9, depending on species
Water requirement: Regular water while blooming
Light requirement: Full sun
Mature size: Varies by species
Tolerances/environmental benefits: Drought tolerant, deer and pest resistant
Every spring and summer, orbed clusters of white, pink, purple, red, yellow and even blue flowers appear on the tops allium's tall, leafless stems, making the garden a living party. Floral lollipops poke their heads above surrounding foliage and give a friendly garden welcome. I feel like these flowers would be smiling if they could.
With more than 500 species to choose from, it can be hard to pin down which allium is right for you. For now, here are three popular and highly rated allium species.