Alliums are bulbous perennials, living up to four years after planting. With a long flowering season, they bloom for weeks on end, bridging the gap between spring and summer. Loved by bees, alliums bear beautiful pompom flowers in shades of purple pink and white, and look fantastic when planted in large groups. Alliums make excellent cut flowers, both in fresh and dried flower arrangements.
Alliums are a popular and versatile group of flowering plants that include ornamental flowering onions, garlic, shallots, leeks, and chives. These hardy perennials are easy to grow, handle a range of climates, and add pops of color and visual interest to gardens and landscape designs. In this comprehensive guide, we’ll explore the different stages of the allium plant life cycle so you can understand what to expect as your alliums grow and ensure they thrive.
Stage 1: Planting Allium Bulbs
The growth of an allium plant begins with planting the bulb. Allium bulbs are planted in fall typically between September and November depending on your gardening zone. This gives the bulbs time to establish roots before winter dormancy.
When selecting a planting site, choose an area with full sun exposure and well-draining soil. Alliums won’t thrive in soggy or compacted soil. Amend the soil with compost or organic matter to improve drainage.
To plant the bulbs, dig holes 2-3 times as deep as the bulb is tall. Space the holes 4-6 inches apart. Place the bulbs root-side down in the holes with the pointed tops facing up. Backfill the holes and water thoroughly after planting. Add a 2-3 inch layer of mulch around the bulbs to insulate them over winter.
Stage 2: Root Growth and Emergence
After planting, the allium bulbs remain dormant through the winter months. Below the soil surface, roots start to emerge from the basal plate at the bottom of the bulb. A strong root system is important for absorbing water and nutrients required for growth.
As spring warmth returns, usually between February and April, the allium leaves begin emerging from the bulbs Slender, grasslike foliage starts to unfurl. Don’t remove these leaves – they are photosynthesizing and fueling the plant’s growth
Make sure the soil stays moist during this stage. Water the alliums weekly if rain is lacking. Hold off on fertilizing until the plants are actively growing.
Stage 3: Leaf and Stem Development
In early to mid spring, the allium leaves elongate and reach their full size. The strap-shaped foliage may be green, blue-green, or purple depending on variety. Leaves can grow 12-18 inches long.
Also during this stage, a long, stiff stem begins to rise from the bulb, eventually growing 1-4 feet tall depending on the allium variety. The stem will support the flower head.
Alliums grow quickly at this stage as the weather warms. Make sure they receive 1-2 inches of water per week if natural rain is insufficient. Fertilize lightly with a balanced soluble fertilizer. Weed and mulch around the plants.
Stage 4: Flower Bud Formation
As allium stems finish growing upright, a flower bud starts to form on the top of the stem. Enclosed by a thin layer of leaves called spathes, the bud gradually swells as the flowers develop inside.
During this stage, avoid overfertilizing the plants which can lead to leaf growth rather than flowers. Water thoroughly keeping soil moderately moist. Stake tall varieties if needed for extra support against winds.
Stage 5: Blooming
Early to late summer is the peak blooming time for most allium varieties. The buds burst open into large, spherical flower heads up to 8 inches wide! The blossoms last for 2-3 weeks.
Different allium species and cultivars bloom in different colors – white, pink, purple, blue and bicolors. The blossoms are long-lasting as cut flowers. Alliums attract pollinators like bees, butterflies and hummingbirds to the garden.
Deadhead spent blooms to encourage potential reblooming. Trim back floppy foliage if desired. Continue watering while in bloom.
Stage 6: Seed Head Formation
After blooming finishes, the flowers give way to seed heads which hold hundreds of small black allium seeds. The seed heads add nice visual interest to the garden after the main flower show is over.
If you don’t want the plants to self-seed, simply snip off the drying seed heads once the petals drop off. Otherwise, allow the seeds to mature and drop to the ground for new volunteer seedlings next year.
Stage 7: Foliage Decline
As the seeds ripen, the allium foliage starts to yellow and wither. By late summer, the leaves completely dry up. Don’t cut back the foliage until it is fully dried up, as the dying leaves are still providing nutrients back to the bulb.
Allow the foliage to remain in place for 6-8 weeks after blooming finishes. When it is brown and shriveled, you can cut it off near ground level.
Stage 8: Dormancy
After the leaves die back completely, the allium plant enters a dormant period through the fall and winter. The bulb uses this time to recharge and prepare for the next growth cycle.
While dormant, the bulbs can be left in place or carefully dug up and divided if desired. Store harvested bulbs in a dry, well-ventilated area until ready to replant in fall.
Growing Alliums in Pots
Alliums adapt well when grown in containers. Plant them in pots with drainage holes, using a quality potting mix. Choose proportionally sized pots – larges varieties like Allium giganteum need bigger containers.
Follow the same planting depth and spacing as in the garden. Position pots in full sun. Water thoroughly when soil dries out, taking care not to overwater. Fertilize lightly every 2-3 weeks during active growth.
Bring potted alliums indoors to a cool, sunny spot once they finish blooming. Allow the foliage to die back naturally before storing the dormant bulbs in a dry place until fall.
Common Allium Varieties
Many species and hybrids exist within the Allium genus. Here are some of the most popular types:
-
Drumstick alliums – Named for their egg-shaped flower heads on long stems. Varieties include Allium sphaerocephalon (Persian onion) and Allium cyathophorum (Violet Garlic).
-
Globemaster allium – A hybrid with huge, 8-10 inch, violet flower heads and sturdy 3 foot stems. Striking focal point.
-
Gladiator allium – A robust hybrid bearing rounded heads of rose-purple blooms on strong, 18-30 inch stems.
-
Millenium allium – A mid-sized allium with glowing purple-pink spheres surrounded by starry florets. Grows 15-18 inches tall.
-
Purple sensation allium – Vivid spherical blooms of glistening purple emerge on 18-20 inch stems. Blooms early-mid summer.
-
Summer Drummer allium – Domed deep violet flower heads in early summer. Grows 24 inches tall.
Growing Tips for Healthy Alliums
Here are some top tips for successfully growing alliums:
- Plant in full sun (at least 6 hours daily)
- Choose well-draining soil and avoid wet feet
- Allow for good air circulation between plants
- Fertilize lightly in spring when growth resumes
- Water 1-2 inches per week during growth and blooms
- Cut off faded blooms and seed heads
- Allow foliage to fully ripen before removing
- Plant in clusters for maximum impact
- Mix heights and varieties for interest
- Mulch around plants to control weeds
- Divide large bulbs every 2-3 years as needed
Troubleshooting Common Allium Problems
-
Leaves distorted or curling – Could be thrips damage. Control with insecticidal soap.
-
Flowers small – Often due to overcrowding. Allow for adequate spacing between bulbs.
-
Foliage yellowing – Can indicate overwatering. Allow soil to dry between waterings.
-
No flowers – Caused by inadequate sun exposure. Move to a sunnier site.
-
Flowers toppling over – Stake tall varieties to support heavy flower heads.
The Rewarding Beauty of Alliums
As you can see, alliums transition through a succession of life stages as they journey from bulb to bloom and back again. By understanding the allium growth cycle and tending to their needs, you can achieve a dramatic display of allium flowers in your garden year after year. The globes of color and rich textures make alliums a rewarding addition to both beds and borders.
Where to plant alliums
Alliums do best in a sunny spot in a very well-drained soil. They’re not fussy about soil type. Plant taller varieties towards the back of a border and shorter-growing types in the front. Alliums are well suited to growing in pots but their strappy foliage can look unsightly after flowering.
Alliums produce foliage before the flowers appear. This often means they’re better suited to the middle of a border where the faded foliage will go unnoticed while the flowers put on a show. To avoid seeing the faded foliage, plant alliums in amongst ornamental grasses and perennials.
For a dramatic display, grow alliums in large drifts through the border or naturalise them in your lawn.
How to grow alliums
Grow alliums in moist but well-drained soil in full sun. Plant as many as you can afford to buy – the most impressive allium displays arise from mass plantings. It’s a good idea to grow them among low-growing herbaceous plants, which hide their unsightly strappy foliage after flowering. Let allium foliage die down naturally after blooming and consider leaving the flower heads in place as they look attractive in their own right, particularly in winter. Mulch annually with well-rotted compost or manure.
When choosing alliums to grow, think about your garden space. Will you be growing in drifts through the border or planting in bulk, in pots? As part of a prairie planting scheme or something more formal? It’s also important to think about the colour of your alliums – most allium flowers are purple but some come in shades of blue, white, yellow and pink. Also consider the size of your allium – that’s the flower size as well as the overall height of the plant. Flower sizes range from just a few centimetres to over 20cm (8in) in diameter, while the eight of alliums can vary significantly, too.
Large, tall alliums such as ‘Purple Rain’ and ‘Globemaster’ work well when planted individually or in drifts. Shorter varieties such as Allium christophii work well in pots. Drumstick alliums such as Allium sphaerocephalon look great in prairie planting schemes.
Allium Planting Guide // How to Plant, Grow, and Care for Allium Flowers // Northlawn Flower Farm
FAQ
What are the stages of allium growth?
What is the life cycle of allium?
What do alliums look like when growing?
How quickly do allium bulbs multiply?
What is the 3rd stage of Allium plant growth?
In the third stage of Allium plant growth, the bulb begins to form. The bulb is an essential part of the plant as it stores nutrients and water for future use. During this stage, it is crucial to provide ample sunlight to the plant to encourage healthy bulb development. The flowering stage is when the Allium plant produces its iconic round blooms.
How long does Allium take to grow?
The first stage of Allium plant growth is germination. During this stage, the seedling emerges from the soil and forms its initial roots and leaves. The germination period can take anywhere between 5 to 10 days, depending on the variety of Allium. After the germination stage, the plant enters the vegetative stage.
What happens after Allium flowering?
After the flowering stage, the plant enters a dormant phase where it withdraws energy from its leaves and stem back into its bulb for future growth. This phase typically happens in the fall or winter months when temperatures begin to drop. Understanding these various stages of Allium plant growth is essential for successful cultivation.
What happens after the germination stage of Allium plant?
After the germination stage, the plant enters the vegetative stage. This is when the plant grows more leaves and establishes a stronger root system. During this stage, it is essential to ensure that the Allium plant receives adequate nutrients and water to support its growth. In the third stage of Allium plant growth, the bulb begins to form.