I know you have one somewhere. Under that conifer, in that corner where the fences meet, along the side of the passageway, at the base of that hedge – just about every garden in the country has an area of dry shade where nothing seems to thrive. It's where the wheelie bins get dumped, where the shed goes. It's the patch of dark and dusty soil that reminds you perhaps you're not quite as good a gardener as you'd like to be.
But it need not be that way. Many of us have become accustomed to our gardens becoming drier. We've learnt about drought-resistant plants and expanded our palette of plants to turn a problem into an opportunity. And whatever pessimistic gardeners will tell you – sounds like an oxymoron, doesn't it; don't you have to be an optimist to be a gardener? – shade has never been anything but an opportunity to grow the many wonderful woodland plants from around the world. But put the two together – dry shade – and the situation becomes a little more difficult.
So, what's the problem?
Shade comes in many forms. Plants in the shade of a north-facing fence or wall still receive plenty of light from above and a wide range of cold-hardy plants will thrive there. By contrast, under evergreen trees the shade is year-round and often dense; this is the most difficult dry shade situation. Shade under deciduous trees is often exactly what woodland plants need, but deciduous trees vary enormously in the degree of shade they cast.
Some deciduous trees including horse chestnut (Aesculus hippocastanum), hawthorn (Crataegus monogyna) and laburnum (Laburnum anagyroides) unfurl their leaves and begin to cast shade early in the year so the plants below have a short window of good light. Deciduous trees also vary in the density of the shade they cast with sycamore (Acer pseudoplatanus), London plane (Platanus x hispanica) and flowering cherries (Prunus) casting unusually dense shade under which relatively few plants will grow. Unfortunately, there are a few trees which combine these two unhelpful features and under which many plants struggle, and these include Norway maple (Acer platanoides), beech (Fagus sylvatica) and crab apples (Malus).
But even a long season shading effect is not a cause for despair. Shade from both evergreen and deciduous trees can be reduced by thoughtful pruning. Simply removing one or two lower branches to allow more light in from the side can instantly expand planting possibilities. In fact, the lower branches of conifers, especially spruces and firs, often become rather sparsely clothed in foliage and removing them not only allows in more light but also improves the look of the trees. Classic specimen trees, cedars and weeping beeches for example, should be left unpruned; we may not be able to plant beneath them but we can enjoy their mature elegance.
A more skilled job is crown thinning, the thoughtful removal of branches from within the crown of the tree. This is a task for a qualified tree surgeon. Thinning the crown will allow more light through to the ground below so more plants can thrive.
So while some shady areas are less of a problem than they first appear and the shade of trees can be mitigated – what about drought? Drought is the more serious part of the problem.
Tree roots obviously take moisture from the soil but this is a problem we can solve. In some situations, simply working well rotted, moisture-holding humus into the soil will improve conditions enough to significantly expand the range of plant choices. But, of course, the very presence of those roots can make this difficult.
A more thorough approach is to create a raised bed in the problem area – an extra 15-23cm/6-9in of fertile, moisture-retentive soil will transform your planting possibilities. Use stone, boards, bricks, logs to retain the new soil, lay landscape fabric over the whole area to hold back eager tree roots for a while, and fill with new soil.
The obvious solution is to turn on the sprinkler. No. This is the most wasteful way to water. Seep hose, sometimes called soaker hose, is far more efficient. This microperforated black pipe, often manufactured from recycled car tyres, is laid on the soil and when connected to the tap a steady stream of water seeps from its pores and soaks straight into the soil. If it runs under a mulch, so much the better.
So... Reduce the amount of shade by thoughtful tree planting and careful pruning of established trees; raise soil levels by adding good soil; use seephose to provide plants with moisture.
Now, the plants. There are two ways of choosing plants for dry shade. If you've added moisture to your dry shade then the classic shade-loving shrubs and spring woodland flowers are available to you. If, however, it's not been possible, choose from a range of attractive but resilient plants which will cope with the situation.
Evergreens – shrubs or perennials – absorb light for 12 months of the year. Aucubas, Japanese laurel, were a staple of old-fashioned municipal shrubberies, but one of the reasons that they eventually became scorned was that they survived so well they became too familiar. Recently introduced variegated types like the male 'Pepper Pot' and female red-berried 'Gold Dust' plus the all-green'Rozannie' have lifted aucuba from the mundane to the desired. This is a top dry shade shrub.
Ever since passing one every winter's morning while a student at Kew decades ago, I've always planted Christmas box (Sarcococca) and these fragrant evergreen shrubs are also dry shade stalwarts. Never invasive, always flowering reliably in winter, always fragrant, look for the white-flowered S. confusa or the shorter, pink-flowered S. hookeriana 'humilis'. Both have black berries.
I'm also a big fan of two uncommon but related evergreen berrying shrubs which not only thrive in dry shade but which provide valuable and unusually long-lasting cut foliage for the house. Butcher's broom (Ruscus aculeatus) and poet's laurel (Danae racemosa) will steadily expand into covetous clumps from which stems can be cut without ruining the effect.
Both develop long-lasting red berries, the Danae in a slightly more orangey tone, but unless you choose your Ruscus carefully, you'll need both a male and a female plant. 'Wheeler's Variety', the very compact 'John Redmond' and a number of plants simply known as hermaphrodite form will produce berries alone.
Among perennials, there's a huge choice. Arum italicum is a wintergreen perennial, it emerges in late summer and the marvellously marked foliage with its bright white veins is vivid all winter. And there are vibrant heads of orange-red berries in late summer. Look for 'Marmoratum', and the larger-leaved 'White Winter'.
Bergenias combine impressive flowers with mostly evergreen foliage which colours well in winter. Forget the deciduous sorts for dry shade. Choose forms which are naturally tight in growth, as when they stretch in the shade they'll not flop. 'Eroica' and 'Overture' have purplish-red winter foliage and deep-red spring flowers. 'Eric Smith' has the best beetroot winter foliage and cerise flowers, B. stracheyi 'Alba Group' is neat, bright and white but with little more than reddish winter tints.
Finally, we always think of ferns as needing plenty of moisture, but some of the shield ferns, Polystichum, are happy in dry shade once established. In fact, the soft shield fern, P. setiferum, is one of the most dependable of all dry shade plants, with many lacy forms that sit well with broader-leaved shrubs and perennials.
Having chosen your plants, there's a trick that helps all these dry shade choices give their best: they all appreciate a good start. Plant in autumn, water the plants with liquid feed the day before planting. Dig an unusually large hole and improve the soil with humus, water in with liquid feed after planting and water again in dry spells and in spring.
Once they've settled in, you'll never again think that your patch of dry shade was the perfect place for the shed.
Graham Rice is Editor-in-Chief of the Royal Horticultural Society's 'Encyclopedia of Perennials' and has grown a huge number of plants searching for those to include in his new book, 'Planting the Dry Shade Garden' (Timber Press) and killed many of them in the process. To find out more about the book, go to dryshadegarden.co.uk. To order 'Planting The Dry Shade Garden' go to amzn.to/IndyDryShade. Follow his blog at transatlanticgardener.com.
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