One of the great ‘discoveries’ of my unwatered ‘steppe’ garden has been Euphorbia ‘Copton Ash’.
I’d admired it, from a distance, for several years. It’s always hard to recall why you overlooked something once you no longer do, but I think it was simply the fact that until I set aside a whole zone for lower growing stuff, I never had a context, in the rough and tumble of a garden based largely on tall perennials, for something below knee height.
But after several years of internal nagging about what I was missing out on by insisting on dramatic height, I cooked up a satisfying context for the lower stuff, and the previously overlooked Euphorbia ‘Copton Ash’ immediately rose to hero status.
Euphorbia ‘Copton Ash’ dons fine blue grey foliage that arranges itself predictably and pleasingly along unbranched stems, arising from a dense growth point, creating a dome – a virtual vegetable hedgehog, to about 40cm. From late spring, each stem gives rise to a great froth of classic lime-green flowers whose acidity and vivacity are amplified by the contrast with the blue-green of the leaves.
The whole structure of the plant is sufficiently loose and open to allow light through, making it the perfect companion through which other low-growing plants might puncture. I had for many years dismissed the bulbous Triteleia laxa (probably best known by a previous name – Brodiaea ‘Queen Fabiola’) as near to useless, what with its foliage turning brown as the navy flowers emerge, leaving the flowers looking self-conscious and entirely unsupported, until I hit on the combination with Euphorbia ‘Copton Ash’. The foliage of the bulb has access to light as the dome of euphorbia foliage expands, only being engulfed as it starts to die off. As the euphorbia becomes a little more open and lax with the onset of flowering, the stems settle around those of the triteleia, supporting them both visually and physically, and providing them with the perfect complementary colour.
I’ve since introduced Verbena rigida to this part of the garden, and this has spread with a little more (only a very little more) vigour than I’m entirely comfortable with, and likewise punctures through the euphorbia. But having such slender foliage of its own, it provides no competition for light so doesn’t undermine the euphorbia in any way. The consequent purple/lime combination is rather more brash than the navy/lime combination elsewhere, but I’m not afraid of a bit of brashness.
While the Lambley nursery catalogue suggests that Euphorbia ‘Copton Ash’ produces a succession of blooms over a long period, I find that in my setting (perhaps due to absolutely no irrigation) the flowers are mostly produced in a pre-Christmas flush, and that they’re just exceptionally long lasting, rather than continuously produced. In fact, they’ll last right through the summer, and into the autumn, fading somewhat, but never entirely losing that rare charm of lime-green over blue-green. I don’t usually find any reason to dead-head them until well into winter.
While it’s firmly evergreen, Euphorbia ‘Copton Ash’ is at its least appealing, for me, in winter. I expect that’s largely due to the hostile and long-lasting low temperatures around here, and the corresponding rainfall over soil that’s probably not quite well-drained enough to keep them partying year ‘round. In better conditions, they’d provide a really worthwhile ‘bun’ of young leaves right the winter through.
Like lots of evergreen euphorbias, my plants of Euphorbia ‘Copton Ash’ are starting to look a bit past their best at six-or-so years of age. But with all the work they’ve done, and joy they’ve given, I’ll gratefully ‘retire’ this first generation, and get on with a replant.
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