Some plants entrance one week and exasperate the next. Rather like many loved ones really.

More than any other, the superb smoky blue of Siberian Iris (Iris siberica – what else?) displayed in profusion each spring captures the heart (how could I ever criticize it?) then subsides into a rough stack of straw in late autumn (how could I ever tolerate it?) and really, really, this time I shall dig it up from amongst all the irises near the front gate, leaving behind only well-behaved, evergreen species and varieties. I love their upright sword-shaped foliage, so important for textural contrast, but the few evergreen iris that will tolerate this oft-soaked spot (near the present unfortunate `moat’) seem to be not-quite blues but tend towards purple; beautiful, but not reaching that perfect note that soars. Amongst them the moisture-loving Japanese Iris flower fleetingly in spring but with a huge presence; their leaves, while deciduous here, don’t remain standing like some unfortunate ghost come winter; they’ve earned their keep.

Behind the iris, sky-blue Bog Sage (Salvia uliginosa) will have to go too; the flower colour is incomparable but the wandering perennial is messy; intolerable near the entrance and probably only a plant for a really large garden. Even then…while a desirable quality in others (at times), it’s too diffuse, really.

I do want a good height of shrub or perennial, though, behind the iris; something more substantial, to enclose the area to make it intimate: to say: `this is an oasis, a human-scale garden you’ve entered from the rough bushland; a deliberate attempt to tame nature where (as says Hugh Johnson) `the essence is control’. In my country garden, though, I also heed Mirabel Osler who famously asked us too-neat gardeners to consider `a gentle plea for chaos’. (As a lazy gardener I take comfort from the latter.)

 I haven’t searched far literally or figuratively: in wet years Salvia guaranitica –try saying that after a few drinks! - (Syn S. ambigens) reaches over 2m and throws up its dense stalks to fill an area quickly, and displays deep blue flowers (a mecca for honey eaters) from late spring until frost arrives.  From South America, it’s also known, sometimes, as Anise-scented sage or Hummingbird sage and it does not like droughts.

It’s the cheaper option, pulling up a bit of a perennial here and tossing it there, but it helps give the garden a little much-needed unity and also I know it will grow fast in that moist area; I shan’t be trying something new here – I’d rather know how it will grow. Of course there’s no real certainty in the garden but relative certainty is a lovely feeling. And I admit I love a plant that flowers for 6 months; it’s hard to trump that – often overlooked - virtue.