It can be toxic to people and pets.
Allium Care
Here are the main care requirements for ornamental onion.
Soil
Alliums prefer asoil pHthat is slightly acidic, at around 5.5 to 6.5.
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However, how well the soil drains is far more important than soil pH.
Do not let the bulbs sit in damp soil, especially during their dormant season.
If they remain wet for too long, they will rot.
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Water
Alliums need infrequent watering, and if it rains often that should do the trick.
Otherwise, watering every three to five days is fine or during times of prolonged drought.
Fertilizer
If you regularly amend your soil, you may not need to feed them at all.
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This can be in late summer or early fall.
Types of Allium
Pruning
Alliums do not repeat bloom.
Propagating Allium
Bulb-forming alliums are very slow to multiply.
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Here’s how:
Rhizome-forming alliums can be lifted and divided any time the clump starts looking crowded.
Don’t wait until the center of the plant dies out, before dividing.
Common Pests/Diseases
Ornamental onions, like their culinary cousins, don’t attract too many pests.
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Deer and rodents avoid them.
However, there are a few varieties that bloom later in the season, even well into fall.
What Do Ornamental Allium Flowers Look and Smell Like?
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There can be as many as a dozen flowers in a cluster.
Blooms vary among varieties of allium.
Some have only 1-inch flower heads while others have 8-inch flower heads.
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Colors range from white to pink and purple.
The odor from ornamental onion comes from the stalks and leaves more so than the flowers.
How to Encourage More Blooms
Promote plentiful blooms by deadheading any spent flower heads at the base.
Additionally, you’ve got the option to stake taller varieties to support the blooms.
A slow-release granular fertilizer in late summer will ensure nutrients stay balanced throughout the season.
Always check the variety you’re planting first if you think this could be a problem in your area.
The odor will strengthen if the leaves are crushed.
A fan may be needed to keep the air moving.
North Carolina State University Extension.
The Maine Organic Gardeners and Farmers Association.
Allium neapolitanum.North Carolina State University Extension.
