

Helen McKerral shares her tips for success with herbaceous Northern Hemisphere perennials
Misty mornings, rolling emerald hills, pastel skies, and that glorious jumble
of colour in English cottage gardens… a sight to feed the dreams of many an
Australian gardener. Those famous cottage perennials - foxgloves and
bellflowers, paeonies and primulas, cranesbills and lungworts - thrive in a
country where a day of 29 Celsius is considered a scorcher; and where snow and
ice freeze the ground throughout winter. No surprise, then, that when
transported to one of the driest continents in the world, where 40 Celsius in
the shade in summer raises no eyebrows, these plants all too often shrivel up in
disgust. Luckily, with a little know-how, gardeners in many areas of Australian
can succeed with cottage perennials for shade.
Herbaceous perennials are plants without woody stems; instead, leaves arise from underground roots or a crown, or are supported by sappy green stems. Northern hemisphere herbaceous perennials, like those of Northern Europe and the UK, are also generally deciduous: that is, they lose their green above-ground parts (leaves and stems) in autumn, storing nutrients in their underground parts and using them to grow again after the spring thaw. This evolutionary trick is no accident, for they are perfectly adapted to surviving freezing conditions: if you’ve seen steamed spinach, you can imagine what snow and ice do to leaves during winter!
The leaves themselves, when they emerge in spring, are usually soft, medium to large in size, and green. Contrast them with many of our Australian native plants’ small, leathery, silvery or hairy leaves designed to handle desiccating conditions, and you’ll see why Australian gardeners growing Northern Hemisphere herbaceous perennials need a few tricks of their own.
Consider your local climate. If your garden is sheltered and in a cool region of temperate Australia, where summer temperatures rarely reach thirty-five degrees, you’ll be able to grow most of the commonly available herbaceous perennials. A tropical climate, on the other hand, is anathema to many herbaceous perennials, which tend to rot in the humidity or fail to go dormant. The best you can do is to provide perfect drainage and an open, airy spot; check local (rather than mail order or interstate) nurseries for perennials that can tolerate your conditions.
If you live in a warm temperate region of Australia with high summer temperatures, remember that those misty English skies mean that the "full sun" conditions recommended by overseas publications for many herbaceous perennials do NOT equate to Australian full sun conditions! In this case, less is more! Plants that need full sun in England, here generally prefer "morning sun" or "half sun" (sunlight for half the day only), or dappled shade (as is provided by the open canopy of many of our native trees); some perennials will tolerate the deep shade of buildings and fences. Shelter from strong winds and protection from the very hottest late afternoon sun is always of benefit - blooms last longer, and leaves are less likely to scorch or wilt.
As these perennials lose their above-ground parts during dormancy, it’s all too easy to forget their location and dig them up or plant over them by mistake (believe me, it is VERY easy!), so mark them with a small stake or tag at planting time.
Protect new shoots from slugs, snails and possums - predation in early spring can set back or kill the plants. Mulch plants with well-rotted compost in late winter; divide spring flowering deciduous perennials in late autumn, and autumn-flowering ones in late winter/early spring. Remember that you can easily transplant these perennials if they’re unhappy in their first home.
Herbaceous Deciduous Perennials for Shade:
LUNGWORT (Pulmonaria spp.)
These glorious long-lived perennials like moist conditions and thrive in morning sun to very deep shade. Their flowers appear from spring to summer in pretty shades of pink, blue and purple, but their stunning silver- blotched, speckled or splashed leaves are equally beautiful.
WINDFLOWERS (Anemone spp.)
The most well-known of these is the Japanese Windflower (Anemone x hybrida), with its 80cm high clumps of large leaves and pink or white flowers floating like large butterflies above the foliage. Japanese windflowers are hardy and can be moderately invasive in some gardens, so give it plenty of room to spread. Look also for the more delicate woodland anemone (A. sylvestris).
CHINESE FOXGLOVE (Rehmannia elata)
A glorious short-lived perennial for half/morning sun, with spectacular veined pink blooms. Grows easily from seed and division. Does best in rich, well-drained soil, with protection from slugs and snails.
CRANESBILLS (Geranium spp.)
No, not the common garden shrub or climbing geraniums (which are, in fact, Pelargonium spp.), but the true clump-forming herbaceous perennials. Some prefer full sun (e.g. G. incanum), but many do better in dappled or half shade in warmer regions. Flowers appear in all shades of pink to purple and blue, from the hot pink G. cinereum subsp. subcaulescens to the almost black mourning widow (G. phaeum). Give geraniums damp, well-drained soil, and divide in autumn.
BELLFLOWERS (Campanula spp.)
Another cottage garden favourite, the bellflower family ranges from the 1m
swaying spires of C. persicifolia in dappled shade, to the mat forming C.
rotundifolia or the compact C. muralis for deepest shade. In moist
areas, C. poscharskyana forms a carpet of blue blooms in the dappled
shade of gum trees. Mail-order and specialist perennial nurseries have the best
range of bellflowers.
PEONIES (Paeonia spp.)
The Paeonia genus includes the deciduous shrubby "tree peonies", but the group we’re concerned with are the herbaceous ones. Peonies are justly famous for their spectacular large flowers, which resemble those of camellias. Herbaceous peonies prefer cold winters, a cool, moist root-run and a sheltered position in filtered sun (full sun in cool areas). Mulch annually in early spring with well-rotted cow manure and avoid disturbing the roots.
COLUMBINES (Aquilegia spp.)
These popular perennials deserve their acclaim for their versatility and the beauty of their intricate, spurred spring/summer blooms. Numerous cultivars, species and hybrids are available from specialist mail order nurseries, while common varieties may be bought as seed (they propagate very easily) or potted specimens from garden centres. Aquilegias tolerate full sun in cool regions, but elsewhere thrive in dappled shade and half sun.
FALSE SPIRAEA (Astilbe spp.)
These beautiful perennials with their ferny leaves and sprays of tiny pink or white flowers need constantly moist, rich soil, dappled shade or morning sun. Propagate by division in winter.
PLANTAIN LILY (Hosta spp.)
These perennials thrive in the darkest, shadiest areas of the garden. Their spikes of pink or white scented flowers are pretty, but they’re really grown for their beautiful large leaves, variously green, olive, golden or variegated. Hostas need rich, fertile, well-drained soil, and ruthless control of snails and slugs. Fertilise hostas throughout the growing season to keep the leaves at their best.
Illustrations from top to
bottom:
Anemone x hybrida
Pulmonaria
Rehmannia elata
Campanula poscharskyana
Aquilegia
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