36-40" tall x 18-24" wide. Eryngium planum ‘Blue Glitter’ (Sea Holly) is an outstanding Old World perennial that blooms in summer with tall stems of spiny, glistening blue flowers. A European bred plant for the cut flower trade (fresh and dried), it is a profuse bloomer that is invaluable for attracting bees and butterflies. It thrives in less than ideal garden conditions.