One allium you cannot miss is Allium cristophii. This bulbous perennial produces pinkish purple globes, 20cm (8in) across, which are made up of approximately 50 individual star-shaped flowers with a metallic sheen. These flower heads appear when the hairy, grey-green, strap shaped leaves start to die back.
This lovely allium is planted en masse in the large beds around Clover Hill at RHS Garden Hyde Hall and from a distance the flower heads form distinct sphere shapes. However, a closer inspection is required to really appreciate the individual starry flowers.
In the garden
Allium cristophii is a frost hardy allium. Bulbs should be planted in the autumn 5-10cm (2-4in) deep ideally in a fertile, well-drained soil, although they seem perfectly happy in the fairly heavy clay soil at Hyde Hall.
Alliums prefer a planting site in full sun, but will tolerate the dappled shade of deciduous trees. Left to its own devices this plant will increase naturally by producing offsets, as it has done at Clover Hill. The offsets can also be removed, grown on and transplanted to another position.
At a height of 30-60cm (12-24in), this allium makes a good companion with other perennials including Geranium ‘Brookside’, Sedum ‘Herbstfreude’ and Salvia nemorosa ‘Lubecca’. The foliage of these later flowering perennials also helps to hide the dying leaves of the allium.
On our Shrub Rose Border A. cristophii is planted amongst the roses giving good understorey and interest before the roses bloom. Our south facing Dry Garden is also a good site for this plant where we have successional planting allowing the allium to flower before the Agapanthus Headbourne hybrids and Zauschneria californica ‘Ed Carman’.
This sparkling allium with its long lasting flowers gives interest from late spring into autumn if the flower heads are left on. They are also excellent for drying and using in flower arrangements.