How long do alliums flower for? This is how long these stunning blooms last, and the best way to extend their flowering

Discovering how long do alliums flower for can inform your choice of blooms and help you ensure you've got constant interest in your flower borders.

For the majority of alliums, their flowering period is a matter of weeks rather than days making them a beautiful addition to your garden border ideas. The specific length of time that an allium is in bloom will vary between varieties, but there are things you can do to extend their flowering season.

By learning how to extend an allium's flowering period now, can provide rich rewards for years to come. ‘Alliums are incredibly perennial and flower for ages,’ says bulb supplier Sarah Raven. ‘I love them for adding late spring and early summer pizzazz. Plus, they are excellent for cutting as both flowers and seedheads and are brilliant for the bees.’

How long do alliums flower for?

How long do alliums flower for differs between varieties; however, as a general rule, alliums flower for a few weeks, maybe up to a month, between late spring and early summer.

If you're looking for an allium with a noteably long flowering time then bigger is better. Experts at Potertons Nursery observed their Allium Globemaster in flower for six weeks in 2024.

Will deadheading alliums produce more blooms?

For lots of plants, deadheading is the go-to method to extend flowering; however, you should not deadhead alliums to produce more flowers. Alliums only produce one flower per stem, so deadheading will not produce further blooms.

In fact, the opposite is true. By not deadheading alliums, you can extend their flowering by letting the seedheads take centre stage throughout autumn and winter. When your alliums have finished flowering, let the seedheads dry.

John Clifford, a garden expert from Gardenstone, adds, ‘Their flowerheads actually look good once they're dead, so many gardeners choose to leave them in place instead of cutting them back.’

What is the best way to extend an allium's flowering seasons?

There are several ways to extend allium's flowering seasons.

The easiest is knowing the best way to to care for alliums. Providing these flowers with the regular amounts of water and treating them with a slow-release fertiliser will keep them healthy and in turn will encourage a longer blooming period.

'For healthy blooms, feeding with a general fertiliser in early spring will provide nutrients during the plant’s spring growth season,' advises garden journalist Hazel Sillver. Try using something like Gro-Sure Granules, available from Amazon, to extend an allium's flowering period.

When it the best time to plant alliums for a long flowering seasons?

Knowing when to plant allium bulbs can also influence the length of time that alliums bloom. 'Usually bulbs planted in October will give the longest flowering time, so if they are planted later, you can expect a shorter blooming time,' explains experts at Dutch Grown.

Why are my alliums not flowering?

There are several reasons why your alliums are not flowering. The most common being that they are not planted in autumn. Plant them too early or too late and your alliums with either flower for a very short period or not at all. Other issues with flowering could be down to watering, a lack of fertiliser or that the bulbs weren’t planted deeply enough