When it comes to Ireland, especially the West, I like to think of myself as reasonably well travelled.
I’ve done my fair share of clifftop walks, scaled the highest peaks, and dandered along sparsely populated beaches, from Renroo on Kerry’s Iveragh Peninsula to Five Fingers Strand on the northerly tip of Inishowen.
Yet it was only last month, on what could’ve very well been the latest in more than three-dozen visits to Co Mayo, that I came across Eryngium maritimum – the sea holly.
Maybe I’ve been unlucky or walking around with my eyes closed, but here on a secluded beach close to most southerly point on the Mullet Peninsula was a plant I’d only ever knowingly encountered before in the wild in Brittany, a part of France that shares many characteristics with Ireland’s west coast.
Zoe Devlin’s Wildflowers of Ireland (wildflowersofireland.net) – the go-to website and book when it comes to identifying Irish wildflowers – indicates that wild sea holly is quite common all around our coastline.
Sea holly (Eryngium planum) growing on a Co Mayo beach
You may even come across it on the dunes at Tyrella in Co Down, a matter of miles from where I live.
The only coastal county from which Eryngium maritimum appears absent is Antrim.
It is described as a “well-known wildflower of coastal places, shingle and sandy beaches”; an upright perennial, measuring 50cm high that is easily identified by its blue-green, prickly, holly-like leaves.
I previously had eryngiums in my garden, and hope to grow them again. In my experience, they are not as robust – or perhaps as tolerant of suboptimal husbandry? – as the not entirely dissimilar echinops, or globe thistles, which continue to prosper in my own garden.
Eryngiums come in a variety of sizes and habits, all worthy of the description ‘striking’. This is not a conventional plant with atypical flowers, but something deemed much more architectural, and definitely exotic.
Sea Holly (Eryngium)
They are prized for their spiky, typically blue, thistle-like flowerheads with a ruff of pointed bracts at the base.
Typically, they will flower from June through to September, and even when the flowers have lost their blue rinse they retain a skeletal elegance, making it the perfect choice for drying.
My favourites are the taller varieties, which will work best in a herbaceous border. Eryngium x oliverianum (Oliver sea holly), with its green spiny leaf rosettes and blue stems, is a popular choice, as is the fellow perennial E x tripartitum, which grows up to 90cm.
Eryngium × zabelii ‘Big Blue’ has the RHS Award of Garden Merit. It is an upright, perennial measuring up to 75cm with spiky, highly-divided, silvery-green foliage.
The biennial E giganteum ‘Silver Ghost’ produces big, eye-catching, silvery white blooms on stems of up to a metre tall. It also self seeds, but look likes a docken initially, meaning it’s too easily weeded out.
Sea Holly (Eryngium)
Smaller varieties are better suited to rock gardens. Eryngium planum ‘Blue Hobbit’ is a smaller variety, ideal for an exposed site or front of a border. Other low growers inlcude E. variifolium and E. bougatii.
With the exception of E x oliverianum, which may need some winter protection, most sea hollies are hardy.
The important thing to bear in mind is the conditions under which they thrive in the wild.
I’m not suggesting you recreate a Co Mayo beach in your garden but ensure they are situated in a good sunny spot, which will also help them grow upright, and in ground that is gritty and well drained.
They will not reward you if left in soggy ground over winter.