Alliums can thrive in either full or partial shade, however full sun is preferred.
The bulbs are typically winter-hardy in hardiness zones 3–8. See this USDA Hardiness Zone Map to determine your growing zone.
Alliums require well-drained soil that does not become wet in order to be cultivated, just like the majority of other bulbs.
Where to Plant Alliums
Most alliums bloom in late spring, right after the last tulips and before irises and peonies, in perennial gardens. The flowers last for weeks and give the garden a balloon-like appearance as they float above it. After flowering, the foliage and flowers disappear, making space for summer perennials to take the lead. Allium christophii, Gladiator, Globemaster, Purple Sensation, and more excellent alliums for perennial gardens include these.
Alliums do well in rock gardens, where they flourish in the well-drained crevices between the boulders. Select species with smaller leaves, such as Allium sikkimense, Allium flavum, and Allium karataviense.
Alliums make great cut flowers, according to cutting gardens. The flowers remain a very long time and are easy to arrange thanks to their rigid stalks. You may guarantee that you’ll always have an abundant supply of flowers for bouquets by planting alliums in a cutting garden. You’ll receive flowers all season long if you select a variety. Purple Sensation, Allium atropurpureum, Mount Everest, Allium sphaerocephalon, and Allium tuberosum are all good choices.
Containers: Whether grown alone or in combination with other plants, many alliums thrive in containers. When the flowers blossom, you can relocate the planter to a visible location so that you can enjoy the flowers.
How to Plant Alliums
When to Plant: Bulbs-based alliums are planted in the fall, just after the first frost and before the ground freezes. Like other perennials, herbaceous alliums (such as Allium tuberosum and Allium millenium) have fibrous roots. You can plant these at any point of the growing season.
Planting Depth and Spacing: Planting depth is based on bulb size. Smaller bulbs, such drumstick alliums, should only be planted 3 deep in comparison to larger bulbs like Globemaster, which should be planted 5 to 6 deep. Follow the plant-specific directions on the packaging or on our website for the best results.
Planting advice: You don’t have to be concerned about deer, squirrels, or voles when growing alliums. Allium bulbs have an onion-like flavor that repulses them, and they almost invariably leave them alone.
How many sun hours do alliums require?
Select a planting place with well-drained soil and exposure to full to at least a half day’s worth of sun. Alliums are normally spaced 4 to 8 inches apart. They will require more space the larger the bulb. Since alliums don’t have a spreading growth habit, planting them close together makes them look nicer.
how do you dry alliums?
Pick off seedheads that are starting to fade and store them for a few months in a cold, dry place, such a shed or cellar. To use as Christmas decorations, I like to dry my seedheads and then spray-paint them silver.
are alliums edible?
Since they are all members of the allium family, onions, leeks, and garlic are often consumed foods. Alliums are theoretically edible, but beware eating any that are designed to be aesthetic garden plants because they may have been chemically treated.
are alliums good for bees?
In the spring, bees and other pollinators are all over our alliums. Our neighborhood beekeeper also claims that the honey doesn’t taste oniony.
do alliums need staking?
Even the tallest alliums won’t need staking since their sturdy stems can hold them if they are planted deeply enough in full sun (so they don’t extend toward the light) and in a sheltered location (so they don’t blow over in the wind).
Do alliums proliferate?
Taller people can need assistance when exposed. After the flowers have faded, let the plant with them until they disintegrate because they make for wonderful winter interest. Some gardeners collect the seedheads and dry them so they can be used as home decor.
Allium bulbs can stay in the garden for multiple seasons. When planting new plants, try to keep in mind where you already put bulbs to prevent damaging those areas.
How to propagate alliums
In a few years, allium bulbs will grow in number. You may occasionally see the white bulbs being pushed out of the ground. Carefully pull the bulbs and gently peel out the offsets in late autumn or very early spring to replant them directly into the ground.
Allium can be grown from seed by leaving the flowerheads on the plant and harvesting the ripe seed to sow right away. Keep in mind that starting alliums from seed requires patience because it takes years to produce a flowering plant.
Growing alliums: pests and problem solving
A fungus called allium white rot prevents the growth of other alliums and onions. Clear and burn the infected plant material, and stay away from growing alliums in the same spot for at least five years, to prevent recurring infections.
Alliums have a tendency to outgrow their surroundings. Learn how to control the amount of alliums growing in a border in this Gardeners’ World video:
What environments favor alliums?
how to cultivate alliums
- simple to grow
- Early spring and summer bring flowers.
- Well-drained soil is ideal for planting.
- tolerate dryness and flourish in direct sunlight.
- Avoid moist areas with dense dirt.
- propagate through aerial bulbils, offsets, or seeds.
- decent cut flowers
- beneficial to pollinators
What ought I to grow in front of the alliums?
Alliums go well with heavy-foliage plants like peonies and iris; position them behind them. Excellent for bedding and diverse borders. Flower heads can be dried well. Many perennial plants, such as Echinacea (Coneflower), Phlox, Alchemilla mollis (Lady’s Mantle), Achillea (Yarrow), and Iris, complement alliums wonderfully.
When should allium bulbs be planted?
Most likely, when you think of alliums, you picture those plants with the traditional round, purple flowerheads on long stalks that make borders look amazing in late spring and early summer. Alliums, however, are much more than this.
There are alliums that are white, pink, blue, and yellow. There are some alliums that resemble a fireworks display, and others that resemble knotted dreadlocks.
You can identify that alliums are related to onions, garlic, and leeks by the aroma released when you crush the foliage. This family also includes chives (Allium schoenoprasum), which have delicious leaves that may be sliced and used to salads and dips.
Alliums are a favorite of butterflies and bees, and even the dried flowerheads look lovely in the border or in floral arrangements.
When to plant allium bulbs
The greatest time to plant alliums is in mid- to late-autumn, at the same time as tulips and daffodils that bloom in the spring. Allium bulbs are resilient and can withstand harsh winter weather if they are planted in soil that drains effectively.
Some attractive alliums, like “Allium sphaerocephalon,” flower in the late summer. Most ornamental alliums bloom in the late spring and early summer.
Where to plant alliums
The majority of alliums thrive in full sun and well-drained soil. Tall alliums should be planted in a protected area to prevent the stems from blowing over in high winds. Plant purple-flowered chives (‘Allium schoenoprasum’), which appreciate afternoon shade, or yellow-flowered ‘Allium moly’ in shaded areas.
Tall alliums look great planted in broad swaths or punctuated across a border. Late-summer bloomer Allium sphaerocephalon has gorgeous wine-red flowers that stand out amid the grasses in prairie planting schemes.
Long, slender leaves on ornamental alliums fade back as the flowers emerge. To conceal the waning foliage, place allium bulbs under other low-growing plants.
Planting allium bulbs
- Remove any weeds by turning the dirt over. Dig in leaf mold or compost instead of using manure on heavy soil as this can change the soil’s pH level. Alliums thrive in soil with a pH that is neutral.
- Make a hole that is roughly four times the bulb’s depth.
- Put a bulb in the opening with the roots pointing down.
- Gently compact the earth after filling the hole.
Alliums can also be grown in large pots with soil that is a mixture of grit, John Innes No. 3 compost, and multipurpose compost.
Tips on caring for alliums
- Ground-planted alliums typically don’t require irrigation.
- In the spring, alliums grown in containers will require regular watering. However, avoid letting the compost become soggy as this could lead to the bulbs rotting.
- Crushed eggshells around plants, copper tape around pots, beer traps, or wildlife-friendly slug pellets can all be used to deter slugs and snails from eating new spring leaves.
- When the plants are in bloom, spread a general-purpose fertilizer to aid in the development of the bulbs, assuring healthy flowers the following year.
- Once the leaves have withered back, remove them.
- There is no need to deadhead the flowerheads unless you choose to because they still look excellent after flowering has completed. As long as they remain in place at the border, they may be ignored.
- Put pots in a greenhouse or up against a wall of a house in the winter to shield them from the cold weather.
Growing allium bulbs from offsets
Offsets, which are little bulbs affixed to the main bulb, are produced by many allium bulbs. These can either be planted directly in the ground or split from the main bulb and placed in tiny pots to grow on. Before they have developed enough to produce flowers, it will take a number of years.
Wait until the allium plants are through flowering before using a garden fork to carefully uproot the plants and inspect the bulbs for offsets. Replant the bulbs after removing any offsets.
Best allium bulbs to plant
Alliums come in a wide variety, from large to little, with flowerheads that are rounded or exotic-looking twisted. Here is a selection of the most well-liked alliums.
- One of the most well-known alliums, Allium ‘Purple Sensation’ has the traditional deep purple spherical flowerheads on long, robust stalks. 1 m (3.5 ft) high.
- Large circular purple flowerheads up to 15 cm (6 in) across on robust stems that are 80 cm (3 ft) tall characterize Allium ‘Globemaster’.
- As its name suggests, Allium giganteum is a true giant with dense, spherical purple flowerheads on stems up to 1.8 meters (6 feet) tall.
Alliums: Should you deadhead them?
The blossoms of allium plants are large, softball-sized, and purple in color. They thrive in areas that are both sunny and protected, where the wind is less likely to tear the blossoms apart. They typically bloom in the early summer under these circumstances and last for three weeks on average.
Deadhead the blossoms once the flowers have gone. However, keep the foliage in place because it needs time to naturally wither in order for the bulbs to store energy for the growth of the following season. It’s a good idea to put alliums in a bed with later flowering flowers that might disguise and obscure them because the leaves may look a touch scraggly.
Why did my alliums not grow again?
Although alliums can suffer in a drought, they do best in well-draining soil (it is a good idea to add some grit when planting bulbs to ensure proper soil drainage around the bulbs).
In the Spring and Summer, the allium may not flower or give a meager show of flowers if conditions are too dry.
Alliums store energy for the following year’s blossoms in their bulbs during the fall, thus persistent dry weather during this time might also hinder a strong flower show.
The most of the year, alliums require little maintenance, but if there is a severe drought in the spring, summer, or fall, give the soil a good soak once a week to make sure the bulbs can access the moisture when needed.
Watering shouldn’t be done in the winter because the bulb is dormant and too much moisture can cause decay.
Alliums in pots are typically more vulnerable to drought than bulbs placed along garden borders. In order to encourage flowering in the spring, water the bulbs once a week consistently if there has been dry weather.
Key Takeaways:
- Alliums typically fail to bloom because the bulb is immature, planted too shallowly, or planted at the incorrect time of year. Alliums can also be prevented from flowering by drought, lack of sunlight, and soggy soil.
- To have enough energy to flower, alliums need to be planted in stony, well-draining soil and be grown in full sun.
- Manure-amended soil and soil that has received nitrogen fertilizer frequently encourage the growth of foliage at the expense of flowering plants.
- In the late Summer and early Fall, pruning the foliage too soon while it is still green can stop the allium from providing the bulb with nutrition, moisture, and energy for the upcoming flowering season. Once the foliage becomes brown, only trim it back.