In the absence of the real thing, what better way to brighten dark days than by creating a blast of artificial sunlight in your garden, writes Jane Powers
REAL SUN HAS BEEN in short supply this autumn. But for spirit-lifting blasts of artificial sunlight, you can't beat the rudbeckia tribe, beaming their little yellow heads off in the late-season garden. There are dozens in cultivation, from the knee-high R. fulgida'Goldsturm' to the two-metre-tall R. laciniata'Herbstsonne'. The name of the latter means "autumn sun", but the broad, drooping petals are more canary-yellow than the gold that one associates with sunlight at this tail end of the year.
The cone-like central boss (which gives the genus its common name of coneflower) merits close-up examination, as its parts are pleasingly arrayed in a perfect, spiralling whorl. Garden anoraks and new-age architects will know that the mathematical sequence that dictates this structure is based on so-called Fibonacci numbers. The geometrically-appealing arrangements that result are often found in nature, and are easily observed in pine cones, pineapples and sunflowers.
Most of the rudbeckias in cultivation have their origins in the damp meadows and moist woodlands of north America, so they appreciate a soil that doesn't become parched in summer. Their relatives, the heleniums, are from similar habitats, but are much more brazen-looking. The flowers may be yellow, orange, rust or red - or any combination of the above. Brave gardeners combine them with other noisy players for a rousing brass band finale to the end of the gardening year.
Possible loud partners include crocosmias, and the other late yellow daisies: coreopsis, heliopsis, sylphium, rudbeckia, perennial sunflowers and, of course, different varieties of helenium. If you weave some wispy grasses such as Stipa tenuissima(ponytail grass) and Anemanthele lessoniana(pheasant's tail grass) through these blaring blooms, it's the equivalent of adding some strings to the horns, providing a calmer, finer layer of interest (and we'll leave the musical metaphor aside now).
Heleniums are commonly known as sneeze-weed, because of the (unproven) belief that they cause hay fever. They are, however, prone to mildew, which may provoke the odd nasal explosion. In the RHS's excellent Encyclopedia of Perennials, edited by Graham Rice (Dorling Kindersley, £25) - a book that rarely leaves my desk - a cosmetic solution that is suggested for the mildew problem is the "Chelsea Chop".
This operation, which is carried out towards the end of May (Chelsea Flower Show time), involves cutting back or pinching out the plants by about half. This results in the blooms being produced on shorter, more bushy stems. If you cut back only the plants at the front of a clump, their more compact growth will hide the mildewy legs of those standing behind.
This kind of selective and pre-season pruning can be applied to many late-flowering herbaceous plants. It is especially useful with species that are inclined to be over leggy or top heavy: the reduced height often means that no staking is necessary. Among the species that respond well to this treatment are the perennial yellow daisies (mentioned above), asters, golden rod ( Solidago), monarda, phlox and veronicastrum.
In my own garden, I sometimes give the late-spring chop to the large, fleshy sedums (such as 'Herbstfreude' and 'Purple Emperor'). It prevents them from splaying out as the season progresses. Sedum'Herbstfreude' (also known as 'Autumn Joy') is the most popular of all the varieties, and rightly so. Its flat, pink plates of flower are full of nectar, and are a magnet for bees and butterflies from mid-August.
The cerise blooms die most elegantly, glowing in all stages of demise, gradually turning to warm maroon and then to deep, rusty brown. The seedheads last all winter, and in spring can be harvested and used in dried flower arrangements.
There are crowds of plants that flower at this time of the year, and a great number of them belong to the daisy family ( Asteraceae). Besides all the yellow daisies discussed earlier, there are the dahlias - which chug along until frost burns them - and that quintessential autumn bloomer, the Michaelmas daisy ( Aster), of which there are hundreds of varieties. I've grown only a few (they usually turn up their heels and die after a season or two in my dry soil), but I do enjoy their mournful purple and mauve flowers.
In the low, honey-coloured sunlight of these final months of the year, they radiate a strange ultraviolet intensity. This year, we're trying 'Little Carlow', which is reputed to be one of the best - and less prone to mildew than some. Other desirable asters, and which are completely resistant to mildew, include A. x frikartii cultivars('Mönch' is the best-known), and varieties of Aster amellus.
Not all Michaelmas daisies are purple-toned: there are plenty of pink and white ones also. The related white wood aster ( A. divaricatusor Eurybia divaricata) is about 40cm tall, and its flowers - although individually inconsequential - throw an airy lace curtain over the ground when seen en masse. It doesn't mind light shade, and looks exquisite under white-trunked birches.
Other members of the daisy clan that are performing now are the tall pink and purple eupatoriums, including varieties of E. purpureumand of our native E. cannabinum. A shrubby, evergreen eupatorium that is not that easy to find is E. ligustrinum, but it's worth looking for, for its scented white, frothy flowers. It's the tiniest bit tender, but will come to no harm in well-drained soil in the sun. As with all eupatoriums, and indeed most daisy relatives, it is a veritable nectar pump, beloved of butterflies and bees.
The autumn-flowering anemones, on their tall, wiry stems, are daisy-ish, but completely unrelated. Often classed as Japanese anemones, they, in fact, originated in China, but some have naturalised in Japan. The white A. x hybrida'Honorine Jobert' and the shocking-pink A. hupehensis var. japonica'Prinz Heinrich' are invaluable for brightening up shady, dry spots.
All Japanese anemones are vigorous spreaders and self-seeders, so don't give them a prime position in the garden, unless you want nothing else in that place.
jpowers@irish-times.ie