By Sarah Wilson published
Once you’ve learned how to plant allium bulbs you’ll never look back. Loved by garden designers everywhere (especially at the Chelsea Flower Show) these easy summer bulbs add a bold ornamental look to borders that fits with modern gardens and cottage gardens alike. Whether planted in a drift or bursting up at random, these pretty balls create an eye-catching feature that’s very on trend.
Whether you’ve opted for modern and minimal or natural and free flowing, alliums will add a cool geometric touch to your flowerbed ideas. Positioning them here and there in a drift of ornamental grasses is guaranteed to make an impact, and they also look good popping up in gravel gardens.
Allium blooms look like floaty powder puffs and come in a range of colors, with everything from dark and dramatic purple to pale mauve and all shades of pink, as well as cool white if you prefer a more neutral palette. Whatever your preference there will be something that works.
Buy alliums as bulbs to plant out in autumn, or if you've missed that window then you can also get them in pots from the garden centre and slot them into any gaps in borders for an instant sensation.
Read on to find out more about how to plant allium bulbs in your garden, plus how to care for alliums once they're in the ground.
Are allium bulbs easy to grow?
Alliums are one of the best plants for beginners as they are super easy to grow in your garden. Follow these key pointers and help your allium plants to thrive:
- Allium bulbs are easy to grow
- They will flower in late spring/early summer
- Allium bulbs are best planted in well-drained gritty soil
- Thrive in full sun
- Once established, alliums are drought tolerant
- Alliums look good planted with ornamental grasses
- Make great cut flowers for the vase
- Butterflies and bees love alliums
- The sculptural seed heads add autumn and winter interest
When it the best time to plant allium bulbs?
Allium bulbs can be bought at the garden center or ordered online for planting in autumn. It's best to plant allium bulbs at the same time as your other spring-flowering bulbs – our guide to planting bulbs has lots of useful tips for this.
Don't worry if you didn't find out how to plant allium bulbs in the autumn, however, as there is an alternative option. You can also pick up potted plants from the garden center or order online for planting in spring and summer. They are widely available. If they're already in flower this also gives you the chance to choose the best flower type for your garden.
Where is the best place to plant allium bulbs?
When finding out how to plant allium bulbs, one of the key considerations is where to plant them. Allium bulbs will generally do best in a sunny spot.
Try planting taller varieties towards the back of a border and shorter-growing alliums in the front. In general, however, alliums are better suited to the middle of a border where the faded foliage will go unnoticed while the flowers put on a show.
For a dramatic display, grow alliums in large drifts through the border, even better if they’re mixed in with grasses. Head over to our guide on how to grow ornamental grasses for our expert tips.
Tall varieties of alliums will do best in a sheltered spot to protect them from the wind.
How to plant allium bulbs
- Grow alliums in moist but well-drained soil in full sun. You might want to opt for a sheltered spot if you’ve chosen tall varieties which could otherwise get blown about in the wind and could snap.
- When planting bulbs make a deep hole, about four times the diameter of the bulb.
- Small varieties should be planted about 10cm apart, while taller ones need to be at least 20cm apart.
- Water well after planting, saturating the soil around the bulbs.
If you have bought plants rather than bulbs, transfer them out to the garden in late spring/early summer. Ease them carefully out of the pot and transfer to a hole with a good handful of grit at the bottom to help drainage. Firm the soil around the plant and water well. Keep an eye on new plants during hot spells but they are generally drought tolerant once established.
Another one of our tips for how to plant allium bulbs is to grow alliums among herbaceous plants or ornamental grasses. Their strappy leaves often take on a yellow hue before they flower which can look a little unsightly, so this is less noticeable when mixed in with other foliage. It also helps to disguise the leaves when they die back after flowering.
Can I plant allium bulbs in a container?
As long as the pot is deep enough your alliums will do well as part of your container gardening ideas. Mix equal parts of peat-free multi-purpose compost and horticultural grit to get the free draining soil that alliums love.
One thing to remember when considering how to plant allium bulbs in pots is to factor in the final height of your alliums. This is important so that the container looks in proportion to your plants. As with all pot-grown plants they will need watering more than if they’re planted in the ground. Our guide on watering plants has some useful tips.
How to care for alliums
Once established there’s very little you need to do to care for alliums as they don't need feeding. Taller varieties of alliums might need staking though.
Let the foliage die down naturally once flowers have faded and leave a few seed heads in place as they add a pretty ornamental touch to your winter garden ideas.
Alliums don’t need overwintering, but if your plants are in containers it's a good idea to move them to a sheltered spot as a precaution.
Are alliums self-seeding?
Alliums are self-seeders, which is great if you favor a naturalistic look, for example if you're rewilding your garden. But if you want them to grow in a more controlled way, snip off any faded flower heads before they have the chance to scatter their seeds around.
Lift, divide and replant clumps of alliums every few years at the end of summer to regenerate your plants.
What are the different types of allium?
Most allium flowers are purple but they also come in shades of blue, white, pink and even yellow, so you'll be able to find a variety to suit your garden color schemes. Flower sizes range from just a few centimeters to over 15cm (6in) in diameter, while the height of alliums can also vary significantly.
Big varieties such as ‘Purple Rain’ and ‘Globemaster’ work well when planted individually or in drifts. Shorter varieties such as sparkly silver filigree Allium christophii work well in pots.
Try Allium schubertii for blooms that look like fireworks, Allium nigrum for a cool white bloom with grey foliage, Allium sphaerocephalon for unusual oval flowers and Allium siculum if you particularly want to attract bees.
If pink is your thing, opt for elegant ‘Summer Beauty’. Essentially lilac-tinged pink, it will add a touch of romantic planting to your garden borders.
Do alliums come back every year?
Alliums will come back each year. Even better is that after a few years they start to multiply so can be a great choice if you're on the lookout for cheap garden ideas.
Sometimes the bulbs are pushed out of the soil as they start spreading. If this happens, in late autumn or very early spring, carefully lift them and gently peel off the new baby bulbs, then plant them straight back in the soil.
Do alliums make good cut flowers?
Arranged either separately as single blooms or a few grouped together in a tall vase, alliums make a stunning indoor display that lasts a couple of weeks. Just add a dash of bleach to the water to keep the taint of onions at bay.
If you want to mix in some foliage try a couple of stems of ornamental grass. The seed heads also look wonderful in autumn arrangements.
Want more suggestions for the best cutting garden flowers? Head over to our guide for the top varieties to add to your planting list.
Where to buy alliums
Now you've learned how to plant allium bulbs, it's time to start choosing the right variety for your planting scheme. You can buy alliums as bulbs or as young plants from the garden centre or online. Shop alliums at the below suppliers, or keep scrolling for some of our favorite picks at the end of the article.
Where to buy alliums in the UK
- Shop alliums at Amazon
- Shop alliums at Crocus
- Shop alliums at Dobies
- Shop alliums at Suttons
- Shop alliums at Thompson & Morgan
- Shop alliums at Waitrose Garden
- Shop alliums at You Garden
Where to buy alliums in the US
4 varieties of allium to try in your garden
With so many wonderful colors and varieties to choose from you're spoiled for choice. Here's a round-up of some of our favourite allium varieties.
Allium 'Purple Sensation' from Thompson & Morgan
One of the best and most majestic alliums for the late-spring garden, 'Purple Sensation' is a sun-loving, drought-tolerant variety producing spectacular lilac-purple flowers up to 15cm in diameter. Plant this among other perennials that also have good structure.
Allium Nigrum from Sarah Raven
This robust variety is long flowering and ideal for adding height and scale to late spring/early summer white-themed planting schemes. The flowers sit on tall, sturdy stems forming flattish clusters with a striking silhouette. Popular with Chelsea Flower Show designers.
Sarah Wilson has been a lifestyle journalist for many years, writing about gardens since 2015. She's written for Gardeningetc.com, Livingetc, Homes & Gardens, as well as Country Homes & Interiors and Modern Gardens magazines.
Her own (small urban) garden is a work in progress - so many ideas, not enough space to cram them in. Hero plants include her ever growing collection of ornamental grasses, black bamboo and ferns, and the perennials like salvias and penstemons that come back reliably year after year. All very restrained though when in fact she'd love to pack her garden with gaudy dahlias and giant cannas, so these are top of her wish list for what to grow next.
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