The Onion Conundrum: the best combinations for planting ornamental Alliums

Alliums are a great addition to a herbaceous border for many months of the year. As Piet Oudolf says “bulbs form a sort of underground army that add an extra dimension to your garden”, they can be used individually as an exclamation mark through a border or in groups creating blocks of colour. Alliums in particular have the additional bonus of not being on the squirrel, deer or rabbit menu!

Allium ‘Globemaster’ Bursting into life

Allium giganteum and A.‘Globemaster’ are real showstoppers. They have the largest heads and add great presence to a border. It is important to remember that by the time they are looking superb, their leaves beneath will look untidy and so need to be hidden. Alchemilla mollisBrunnera, and many of the Geranium family do this job perfectly.

Top tip: plant giant Alliums towards the back of a border.

Allium giganteum underplanted with Geranium. Photo credit: www.edenbrothers.com

Perfect for a white garden, Allium ‘Mount Everest’ is a tall, white Allium that benefits from a dark backdrop for example, yew hedging or evergreen topiary obelisks. I have seen these used to great effect in clumps in the new herbaceous borders at RBG Kew. Again you need to consider the unsightly leaves at the base of the plant.

Planting companions: white lavender, Dicentra (Lamprocapnos) spectabilis ‘Alba’, Astrantia ‘Superstar’, Hellebores & any of the larger white Geraniums.

RBG Kew: Allium ‘Mount Everest’ planted en masse on ‘The Broadwalk’ May 2018

The ‘Drumstick’ Allium, A. sphaerocephalon, has lovely little egg-shaped flower heads in early summer and looks great in a prairie-style planting scheme. Plant it en masse with feather grass Stipa tenuissima and Achillea ‘Terracotta’ for ultimate movement in your garden.

Prairie-style: Stipa tenuissima, Achillea ‘Terracotta’ and Allium sphaerocephalon

Finally, Allium atropurpureum usually grown for it’s rich, deep purple, star-shaped umbels matches beautifully with the dark purple stems of Salvia nemorosa ‘Caradonna’. Planted together, the pair will give a splash of colour in the front/middle of a border from late spring into summer.

Allium atropurpureum planted amongst Monarda, Amsonia & Salvia. Photo credit: www.gardeninacity.wordpress.com

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