Sea hollies (Eryngium) are wickedly cool plants, usually with silvery blue flowerheads and lots of spines. Unfortunately, I don’t have much luck growing them here, except for rattlesnake master (E. yuccifolium), because my soil tends to be on the moist to wet side in winter. A few years ago, I ran across seeds of marsh eryngo (E. aquaticum) from a source in southeastern PA, and it sounded promising as far as moisture tolerance. It wasn’t particularly interesting the first year, when it was just a clump of narrow, somewhat leathery, green leaves, but wow, the next summer, it sent up 4- to 5-foot-tall stalks topped with many dozens of silvery white to silvery blue bloom clusters, each surrounded by spiny-looking bracts. The display begins here in late July and continues for months: even in October, as the first blooms mature their seeds, new clusters are still forming. The plants are likely to self sow.
One thing I particularly like about this species is that it seems less prone to sprawling than rattlesnake master. And, my hands appreciate that, while marsh eryngo appears to be as spiky as other sea hollies, the bracts are more soft than stiff, making it much easier to use the cut stems in arrangements. The flowers attract loads of pollinators, and the seedheads extend the season of interest well into winter. This one has quickly become one of my top favorite plants! It’s native to parts of eastern North America. Full sun. Moist to wet soil is best, but the species can apparently tolerate average garden soil as well. So far, the species is mostly acting like a biennial here, though I did have a couple plants flower two years in a row. Zones 6 to 9.
Collected in late October to early November 2023. At least 15 seeds. PA ecotype. Shipping to US addresses only.
Please read the germination information as well before ordering.