Allium. Wow! These are spectacular!
Flowering anytime from late Spring to early Summer, blue, purple, white or yellow balls on rigid stems burst like frozen fireworks. Grow in borders or containers but the tallest most spectacular ones are best amongst hardy perennials.
As a bonus they last well in floral arrangements and produce interesting seed heads for the winter display. A few will naturalise in grass but all alliums are irresistible to butterflies and other beneficial insects.
As a member of the garlic and onion family, the Allium is tough, versatile and long lived. Although some smaller growing species do well in cooler, moister conditions, most alliums hate cold, exposed or waterlogged conditions, thriving in a sheltered but sunny position in well-drained soil. They also dislike freshly manured soil.
Plant alliums in early autumn, to a depth of roughly four times the diameter of the bulb. Failing that, Cleeve Nursery offers pot grown ones from their nursery in very early spring.
There are allium varieties in heights appropriate for the back and middle of the border: plant smaller ones 8-10cm (3-4”) apart, with taller species at least 20cm (8”) apart.
When lifting and dividing overcrowded clumps [after the foliage and flowers have died down] look out for offsets which can be carefully separated from the bulbs. Replant the divided bulbs and either plant the offsets in their final positions or grow them on in well drained compost. If Alliums like the conditions you provide in your garden, be prepared for them to colonise an area with their spectacular late spring flowers.