agavifolium Large flat whorls of strappy leaves produce very upright, branched stems with large cones of moss-green flowers. 120cm (4ft). £4.50 BUY NOW

alpinum Laced and netted collars sit around a tall central cone of blue. Large, mid-green leaves. 60cm (2ft). £4.60 BUY NOW

bourgatii Silver stars with centres of little, palest green thimbles that mature to sky blue are borne on stout, much branched stems above deeply divided soft green-grey foliage. 60cm (2ft). £4.80 BUY NOW

bourgatii 'Graham Stuart Thomas' Beautifully silver marked leaves with small blue flowers. 60cm (2ft). £5.00 BUY NOW

giganteum   (Miss Willmot's Ghost) Large white collars surround a centre of white flowers. A biennial. Please ask about availability. 90cm (3ft)

horridum An unfortunate name for a handsome plant. Pale green flowers borne on a candelabra of stems above plain green leaves. 90cm (3ft). £4.50 BUY NOW

x oliverianum Very beautiful large heads of soft blue with a large spiky ruff. 90cm (3ft). AGM. £5.40 Sorry sold out

planum Thimble-sized light blue flowers on blue stems above a rosette of deep green leaves. 90cm (3ft). £4.50 BUY NOW

x tripartitum Small light blue flowers with spiky collars. Dark green leaves form a spreading mound. 60cm (2ft). AGM. £4.70 BUY NOW

x variifolium Deep green leaves, handsomely marbled with well-branched stems of silver-blue flowers with slim, silver bracts. 45cm (18in). £4.70 BUY NOW