There are few plants more striking in the garden, right now (just pre-Christmas in the Southern Hemisphere) than the nemorosa-type salvias. They’re powerful in shape (piercingly vertical), in floral density (creating a solid block of colour) and in hue (mostly purples, super-heated by red undertones). In my (and many Aussie’s) current-favourite form, ‘Caradonna’ (though Matt from Antique Perennials reckons I should know better, and that there are far superior forms) even the flower stems are virtually black-purple, which, even lined with flowers are so slender that each stem appears almost thread-like, but dark and wonderfully rich.
These nemorosa-types also happen to be some of the few salvias that will overwinter for those of us in frosty areas. All the shrubby ones, many of Mexican origin, are killed stone-dead by about frost number six, and have to be replanted in late spring each year. But nemorosa types are entirely deciduous, overwintering as near-dormant basal rosettes, and can laugh at the worst any winter can dish up (in Australia, at least). Over about eight to ten weeks from early spring, those basal rosettes shoot up rapidly, carrying smallish, raspy leaves, and terminate in long, emphatically vertical flowerheads that last for several weeks.
That is, without doubt, the least complicated, part of their life-cycle. In human terms, that’s their delightful, trouble-free childhood. They’re so irresistible over this period that it’s tempting to splash them around everywhere, in great sweeps. But their troubled puberty is yet to begin.
Without any intervention, following their spectacular early-summer bloom, flowerheads brown off with virtually no Oudolfian charm. The dome of foliage thins to patchiness, and the remaining leaves often carry a bit of powdery mildew. So to do nothing isn’t an option. The question is what to do, and hence this post. I’m hoping, if you’ve had any experience with these undeniably fabulous plants, that you’ll add below what YOU do, to optimise their impact in your garden.
David Glenn, at Lambley Nursery, has long spruiked the method of cutting them right to the ground after flowering, and stated by doing so he could get up to three cycles of flowering each season. My climate doesn’t provide me with the same response, probably being a few weeks shorter by dint of my elevation and slightly lower temperatures. Treated in this way, I reckon I’d get one and a half displays per summer. And in any case, I not a fan of a ground-level gap in my perennial plantings at this time of year, however temporary that might be.
My management strategy amounts to little more than a thorough dead-head, cutting back to a point where small buds where the leaf meets the stem prove that there’s growth potential. In doing so, I’m usually able to get a second, rather reduced flowering. It seems that the potential for regrowth and re-flowering varies enormously from one named form to another, but as far as I know no one has done any comparative studies, nor documented their results.
By far the wisest insight I’ve had regarding the use of the nemorosa salvias came from German designer Bettina Jaugstetter, who in planning her large naturalistic perennials plantings, never uses them in large clumps, but dots them through the the whole planting. In that way, they make an early summer impact spangled about, but are then cut right to the ground, leaving no noticeable gap (being individual plants), and any further flowering is considered a pure bonus.
There’s a large range of nemorosa-type salvias available in Australia – probably more than we need, to be frank. I admit I couldn’t see the point in the pink form named ‘Amethyst’ until I saw it used repeatedly, and as the only thing in bloom at that time of year, on a section of the High Line in New York. The white forms remain firmly in the ‘why bother?’ category for me, but as nearly every other plant prejudice I’ve had has eventually been firmly and fatally challenged, I’m guessing this one will fall as well, in time.
We’d so love to hear not only how you may have managed the nemerosa type salvias in your garden, but also which are your favourite varieties, and why!