Zone: 4 to 8
Soil: sand to loam
Light: Full sun
Bloom colour: Blue or pale green
Bloom period: July to August
Height: Up to four feet
Moisture:Usually dry to medium
Attracts: A variety of bees and butterflies.
Notes: There are a few species available in nurseries which have steel blue flowers, but they are usually from Europe. Some of these have escaped gardens into more natural settings. Eryngium alpinum is the most striking of these plants and it certainly caught my attention when I saw it growing in its natural habitat in the French alps. The species native to north america that is sometimes available is Eryngium yuccifolium (Rattlesnake Master). The rattlesnake master is an odd looking flower, but it seems to attract a large number of different bees and beneficial wasps. It has far more wildlife value than the imported species. It may not have the good looks of its European cousins, but its oddity value is certainly a conversation starter. This species is native to parts of New England and many other states in the eastern side of the USA, but it is not native to Canada.
Like many other plants, It survives in dry sandy soils by having a deep taproot, so you really have to dig carefully if you want to transplant it. In its first year, it will need some extra watering during droughts to become established. The plant itself is not very wide and a minimum of three specimens should be planted together about 18 inches apart.