You know summer’s on the horizon when dramatic displays of alliums approach their peak, stretching their glorious globes and bold bobbles above leafy perennials still preparing for glory. But after the main early-June show, why not develop the cavalcade of blossom by using other allium species and varieties that will propel your displays into high summer?
While the time for planting dry bulbs is in autumn, do look out for potted plants in nurseries, garden centres and horticultural shows that you can slip into plantings to try them out.
Alliums are so useful, as their long-lasting flower heads are supported on strong stems that enable them to poke above or mingle with other perennials, which can be used to mask or disguise their foliage, which usually has no visual quality or which withers before they flower.
For serious impact they need to be planted in groups of at least five or seven, or more with smaller, slighter forms. Although they look good sited close to perennials, they need plenty of light and air to continue to grow healthily for years, so don’t crowd them out with neighbours.
They can also be grown in pots and make good cut flowers. They’re highly attractive to bees and other pollinators.
Plant dry bulbs in October around 7½-10cm (3-4in) deep in a sunny position in moist, but well-drained soil. Although attractive in seed, many alliums will seed around, so remove flower heads when spent if you don’t want this to happen.
Best Alliums For Summer Impact
A. 'Ambassador'
Large, globe-shaped heads 15cm (6in) across bloom in June and July. Attractive seed heads. H:1.2m (4ft). S:25cm (10in). From: Harts Nursery Tel: 07855 785540.
A. caeruleum
One of the best blue-flowered onions. Azure blue heads of star-shaped flowers in June and July. H: 50cm (20in) S:15cm (6in). From: Sarah Raven Tel: 0345 092 0283
A. flavum
Unusual lax sparkler-like flower heads of bright lemon yellow appear in June and July. Narrow blue-green foliage. H: 38cm (15in) S: 10cm (4in). From: J.Parkers Tel: 0161 848 1100
A 'Forelock'
Taller variety producing oval maroon-red blossoms with top-knot on stout stems from late June. H:1.2m (4ft) S:15cm (6in). From: H.W.Hyde & Son Tel: 011 89340011
A. 'Millennium'
New variety of compact habit. Rounded heads of rose-pink blooms in July and August. Evergreen strap-like foliage. H: 35cm (14in) S:20cm (8in). From: Crocus Tel: 01344 578111
A. sphaerocephalon
Popular and reliable species flowering from July with egg-shaped claret flowers on long slender stems. H: 0.9m (3ft) S:10cm (4in). From: Crocus Tel: 01344 578111