When Mike Morant of Antique Perennials mentioned in his recent Plant of the Week featuring Thalictrum, that Euphorbia rigida would make a worthy subject, my first thought was ‘Already done, Mike!’. I went scrolling back through the (now) twenty seven plants we’ve done to find out how long ago it was that it was featured. There was no sign of it.
Like, what? How is that possible? Euphorbia rigida is a stalwart of my garden year round, and has been nothing less than the star of it throughout late winter and early spring, featuring with embarrassing regularity on my Instagram feed.
So here it is. I vividly recall the introduction of E rigida to the nursery trade, some time in the mid-90’s. I loved its blue-silver colouring, and the mathematical precision of the leaf arrangement, but thought it a bit gawky, and couldn’t figure out how I’d use it in my habitually tall perennial plantings. We kept each other at arms length, Euphorbia rigida and I, for about twenty years.
Then, in order to create a garden context for small bulbs, I started thinking about devoting a whole part of the garden to a low, matrix-like planting of grasses and low, mostly evergreen perennials whose primary purpose was to create a permanent background – the basic warp and weft that could be seasonally gilded with the passing show of bulbs.
A client offered me a few seedlings of Euphorbia rigida, and with mild enthusiasm, they were transplanted into my garden. I had no idea, back then, of just how important they’d become.
Throughout summer – their quietest period – they provide a dome of silver pointed foliage that would have old Mr Fibonacci doing a jig right there in my Steppe. Over winter, the apices of each stem start to colour up and congest, stained with ruby, bronze or lime, before exploding into flowers of screaming sulphur-yellow. Over a month or two these slowly cool to lime, and then, in my climate at least, age to coral and eventually to carmine. No other plant in my garden could boast as many seperate showy stages.
But what’s become clear over this spring, via many instagram accounts, is that not all these stages show for everyone. And many can’t keep it happy at all. The simplest take home message is that it wants it tough. Really tough. It prefers perfectly drained soil, and appears happiest if it gets absolutely no water over summer. Like its cousin, Euphobia characias ‘wulfenii’, it’s happiest where it self sows. Both of these plants seem to be subject to some integration issues when transitioning from the potting mix they were purchased in to the native soil. My experience is that the best performing and longest lived of both are the self-sown offspring of my original plants.
Euphorbia rigida seems curiously tolerant of shade, but is never at its best unless in full sun, Indeed the more sunshine it gets, the more of the pre-flowering colour you’ll get, and the more of the coral seed-head colouring you’ll get. The best of my plants have self-sown into a west-facing bank where they get no water at all. It’s also at its best in company either low than, or at a similar height to it. Consequently I find it to be an almost useless ‘border’ subject, looking best in a sparse, gravel-garden setting, or some other form of naturalistic planting.
Having paid scant attention to Euphorbia rigida for two decades, I don’t now know what I’d do without it. Context is, of course, everything. It seems like it’s going to take at least one full lifetime – maybe one and a half – to really get a grip on that.