With their round, bright purple flower heads growing on naked stems, ornamental alliums are real eye-catchers. Between June and early August, these bulbous blooms finish flowering, leaving many gardeners wondering what to do next.
Most alliums are perennials and should naturally come back year after year. To guarantee their return and encourage an even more dazzling display the following season, there are three key maintenance tasks to consider: deadheading, cutting back the foliage and dividing bulbs.
However, these jobs shouldn't all be tackled at once. While some can be done as soon as flowering finishes, others require a little more patience.
3 jobs for post-flowering allium care
Deadheading
When the blooms are spent and look a bit sad, it’s fine to tidy up the plant a little, says Julian Palphramand, head of plants at British Garden Centres. “You can snip off the dead flower heads if your border needs to look tidier,” he adds.
The foliage, however, is strictly off limits – at least in the first instance. “If you’re just starting with alliums, the most important thing to do after they’ve flowered is to leave the leaves alone,” the plant expert urges.
“It’s tempting to chop everything back once the flower fades, but don’t do it.”
This is because the leaves are vital for the plant’s health and serve a specific purpose. “Those green leaves are what feed the bulb and build up energy for next year’s blooms,” Julian explains.
Cutting back foliage
“Keep the leaves until they turn yellow and then brown and shrivelled. Only then should you cut them down to the ground.”
To keep newer alliums happy and returning, that’s all you need to do. “Leave the bulbs in the soil over winter; they’re hardy and much happier undisturbed. They often get better for a few years in the same spot,” the expert advises.
Dividing bulbs
If you’ve grown alliums for three or four years and start noticing that their flower heads have started growing a little smaller, Julian recommends lifting the bulbs, dividing the crowded clumps and replanting the biggest, healthiest bulbs.
By giving alliums a little post-flowering care and resisting the urge to cut them back too soon, you’ll help ensure stronger plants, larger flower heads and an even more spectacular display next summer.
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Wanda Sachs is the Multiplatform Writer for Country Living and House Beautiful, exploring the latest in gardening, wildlife and sustainable living alongside interiors and property. She is particularly interested in human-interest stories, the intersection of design and pop culture, and the evolving relationship between urban and rural life. Previously, she served as Associate Editor at The Berliner in Berlin, where she reported on culture and fashion. Wanda studied English and German at the Goethe University Frankfurt and Exeter University.
