When should I plant my allium bulbs?

Plant them in the fall before the ground freezes.

Why are my allium leaves turning yellow?

It is normal for the foliage to fade as the plant prepares to bloom or go dormant.

Plant guide

Ornamental Onion.

Allium

Pronounced AL-ee-um

Also known as Garlic, Leek, Onion, Onion, Onions, Wild Onion, alliums, garlic, leek, scallion

Alliums are charming bulbs that bring unique, globe shaped blooms to your garden. They're part of the onion family and offer a wonderful architectural look. You'll find they're quite hardy and add a splash of color in late spring or early summer.

At a glance

Care level: Easy
Plant type: Bulbous perennial
Light: Full sun
Indoor light: Direct sun
Water: Every 7 to 14 days
Mature size: 3 feet
Growth rate: Medium
Hardiness: USDA 3 to 9
Bloom time: Late spring to early summer

Care

Plant your bulbs in well draining soil where they can soak up plenty of sun. Keep an eye out for yellowing foliage after blooming, which is a natural part of their cycle. Ensure they don't sit in soggy soil to prevent the bulbs from rotting.

Watering: Water consistently during the active growing season but allow the soil to dry out slightly between waterings.
Feeding: Apply a balanced bulb fertilizer once in the early spring as new growth emerges.
Pruning: Remove spent flower stalks after blooming, but leave the foliage until it turns yellow and dies back naturally.
Repotting: Divide and repot clumps every few years if the plants become too crowded and flowering decreases.
Soil: Well draining sandy or loamy soil
Soil pH: 6.0 to 7.0
Temperature: -25 to 35°C
Humidity: 30 to 60%
Drought tolerance: Moderate
Lifespan: Perennial, typically 3 to 5 years per bulb cluster
Fragrance: Light
Deer and rabbits: High

Signs it needs repotting

Bulbs are crowded and flowering decreases
Roots growing out of drainage holes

Safety

People: Ingesting large quantities of alliums can cause gastrointestinal distress in humans.
Pets: This plant is toxic to cats and dogs if ingested.
Children: Keep bulbs away from small children as they can be a choking hazard and cause stomach upset if eaten.
Contact allergens: Handling the bulbs or crushed foliage can cause contact dermatitis in sensitive individuals due to sulfur compounds.
Airborne allergens: The pollen is generally not a significant airborne allergen.
Edibility: While many alliums are edible, some wild species are toxic and look similar to poisonous plants, so never consume unless you are certain of the identification.

How to identify it

Spherical clusters of tiny star shaped flowers
Long, slender, grass like basal leaves
Strong onion scent when stems are crushed
Tall, sturdy, leafless flower stalks

Height: 0.15 to 1.2m
Spread: 0.1 to 0.45m
Leaves: green, blue-green, deciduous
Flowers: purple, pink, white, yellow, 2 to 20cm
Fruit: black, Late summer

Problems to watch for

Onion FlyCommon
Onion ThripsCommon
Bulb RotUncommon
Downy MildewUncommon
Root RotUncommon
RustUncommon
Botrytis BlightRare
White RotRare

Allium thrips — Tiny insects that cause silvery streaks on leaves.

By symptom

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Growing it

Propagation: division, seed, bulbils
When to plant: Fall
Overwintering: Leave the bulbs in the ground over winter. They require a period of cold to trigger spring growth.
In containers: They grow well in containers, provided the pot has excellent drainage and is at least 20 cm deep.

Division

1. Dig up the clump after the foliage has died back.
2. Gently pull the bulbs apart.
3. Replant immediately at the recommended depth.

Plant alliums near roses to help mask their scent from aphids.

Grows well with

Peony — Their foliage hides the fading allium leaves.
Catmint — The blue flowers contrast beautifully with purple allium globes.
Roses — Alliums help deter pests from nearby roses.

Similar species

Chives — A smaller, edible relative with similar flower structure.
Garlic — Shares the same genus and pungent chemistry.

Science

Family: Amaryllidaceae
Genus: Allium
Order: Asparagales
Class: Liliopsida
Native range: Northern Hemisphere temperate regions
Conservation: Most ornamental alliums are common and not of conservation concern.

They survive in the wild by storing energy in underground bulbs, allowing them to bloom quickly when conditions are favorable.

Value to wildlife: nectar source
Pollinators: bees, butterflies
Uses: ornamental border, pollinator garden, cut flowers, dried arrangements

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 8/9
Temperature: 5/9
Moisture: 4/9
Nutrients: 5/9

Taxonomy resolved against GBIF.

Questions people ask

When should I plant my allium bulbs?: Plant them in the fall before the ground freezes.
Why are my allium leaves turning yellow?: It is normal for the foliage to fade as the plant prepares to bloom or go dormant.

Where the name comes from

The genus name Allium is the classical Latin term for garlic, while the common name simply refers to the group.

Good to know

Alliums are members of the Amaryllidaceae family, which includes onions and garlic.
The name comes from the Latin word for garlic.
They are naturally deer and rabbit resistant because of their pungent scent.
Dried allium heads look beautiful when spray-painted for holiday crafts.

Also in

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This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.