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May's Plant of the month

A sea of blue – an ocean of cool, calm camassias – is the opening scene on Weather Hill in early May

Camassias make a wonderful display at RHS Garden WisleyThe gently sloping hillside of cornflower blue is a soothing, cooling panorama, set off by the green grass and freshly opening oak leaves above. Looking back, you can see down over the Rock Garden and over to the Wild Garden, with rhododendrons adding their vibrant mix of colours.

It’s a beautiful effect, created by the brilliant North American bulbous plant, Camassia.

In this planting scheme we have two different species. Camassia leichtlinii subsp. suksdorfii Caerulea Group is first to flower, the one that brings the early May beauty. Later in the month, as these ones fade, the lighter blue of Camassia cusickii continues the show.

Both types share the same style of pyramidal flowerhead, up to about 1m (3ft) tall, with starry-shaped flowers around an upright stem. In the humus-rich, fertile, free-draining soil on Weather Hill they flourish. Elsewhere in the garden we grow them in smaller-scale settings, where they are equally at home. Look out for them in the Country Garden too.

Camassias on Weather Hill at WisleyWe planted this mass of camassias about 10 years ago now, and they’ve done so well we added more on the other side of the hill a few years later. Now, the Bowes-Lyon Rose Garden is flanked with naturalised bulbs in the springtime, and the strappy leaves (Chionodoxa and Narcissus are in there too) have time to grow (in order to feed the bulbs for next year) and fade naturally.

The original plantings have the benefit of being beneath a grove of Cornus kousa trees, so the show extends from May into June. It’s a lovely spot for a number of weeks, and the sea of camassias is definitely one of Wisley’s highlights.

We hope to welcome you to see them soon!

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.