Silver in the shade

Sunday, 17 October 2010

Lamium maculatum White Nancy

Silver foliage has long been considered a valuable mixer in any flower border. There are few boring silver-leaved plants: the foliage, in addition to its silveriness, is usually endowed with interesting shapes or textures, providing contrast among green-leafed plants. Silver foliage also enhances the visual appeal of flowers, especially those which are white, blue, pink or cerise, as well as brightening other pastel colours and softening more vibrant colour schemes. As well, repeated groupings of silver plants throughout a border can effectively unify a planting scheme.

Silver leaves usually belong to plants that love sun and good drainage. Artemisia, Stachys, Senecio, lavender, Dianthus, Lychnis - they all glitter in dry sunny border, and indeed the physical properties of the leaves which make them lustrous are normally a protection for the plant against extremes of sunlight, wind, heat and drought.

Plectranthus argentatus with Erigeron karvinskianus daisies

However, there are many silver or grey-silver plants that surprisingly thrive in shade, where their sterling qualities are perhaps of even greater value, for they can illuminate these gloomier parts of the garden to great effect, as well as providing contrasts of colour, shape and texture. Many of these are plants from warm climates, which thrive in our climate with very little maintenance. In the heat of our Sydney summer, a silver-leaved shade garden can give a feeling of cool respite, especially when these plants are sandwiched between plain green leaves or paired with crisp white flowers.

One of the most effective of these is Plectranthus argentatus, a soft-wooded sub-shrub (pictured above), which has large sumptuous leaves like silver velvet, on a plant to 1m tall and as wide. The foliage enhances any neighbouring plant, including shade-dwelling Japanese windflowers, Hydrangea, shrubby begonias or ferns. There are compact forms, such as 'Silver Shield' (ht 30cm) and a groundcover version, 'Nicoletta'. A newly available groundcover cultivar called Plectranthus oertendahlii (marketed as 'Emerald Lace') has beautiful silver veins on rounded leaves.

Helichrysum petiolare

With much smaller leaves of a similar colour and texture is Helichrysum petiolare, a plant usually assumed to be a sun-lover, but one which is surprisingly shade-tolerant. It sends out long arms which cascade over walls or intermingle with other plants; or it can be pruned into a dense thicket about 1m tall.

Pilea cadierei

A good companion to these is the shrubby aluminium plant, Pilea cadierei (ht 45cm), which has glossy green leaves marked with puckered silvery white bumps. It is cold-sensitive, but if planted below a tree canopy, should be protected from mild frosts.

Some of the brake ferns have central silvery-white bands on their leaves: Pteris cretica var. albolineata (ht 80cm) has slim fingers of leaves while Pteris quadriaurita var. argyraea (ht 1m) has feathery fronds. Both provide an excellent contrast amongst broader silver or green leaves or, more dramatically, paired with the dark purple-black foliage of the elephant ears Colocasia 'Black Magic' or black mondo grass (Ophiopogon planiscapus 'Nigrescens', ht 20cm).

Rhizomatous Begonia are also excellent groundcover plants for dry shady sites and amongst their many colours there are silver and silver variegated forms which can expand to shimmering clumps. The leaves are relatively large and often have unusual shapes. B. 'Aquamarine' (ht 20cm) is an excellent example, with broad leaves marbled with silver; 'Silver Jewel' (ht 15cm) has decorative veins of silver on round pebbled leaves.

It is hard to believe that a wandering jew could be recommended for a garden setting, but sophisticated Tradescantia sillamontana (ht 20cm) sports beautiful downy silvery leaves and is not rampant like some of its weedy cousins. Also low growing is Lamium maculatum 'Beacon Silver' (ht 15cm), an effective but controllable groundcover even in quite dense shade. Its glittering heart-shaped leaves are almost all silver except for a narrow green margin, and it has mauve-pink hooded flowers in spring. This plant does enjoy some moisture in the soil but is tolerant of dry times. The cultivar 'White Nancy' has white flowers (pictured at the start of the blog) and 'Pink Pewter' has soft pink blooms.

Another silvery groundcover is Brunnera macrophylla 'Jack Frost', which has quite large heart-shaped silver leaves with green veins (ht 40cm). It is a slower grower than the lamiums, but is an attractive feature plant. It needs reasonable moisture to get it established, but then it can tolerate dry periods. In spring, it has the bonus of clouds of tiny blue flowers like forget-me-nots. It probably is best suited to the cooler elevated Sydney suburbs, as is another silvery leaved woodland genus, Pulmonaria.

There are lots of choices for silver in the shade for Sydney gardens!

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