Grey and silver plants
With the continued forecast of Global Warming and dry summers, there have been many articles on drought tolerant plants. Many of these focus on the prairie plants, grasses and perennials which are quite large, suitable for mass planting and can become thugs in a garden setting.
I have been considering the smaller, daintier subjects which will survive in, or even prefer, dry conditions, and many of these are grey or silver-leaved plants, noted for their foliage. These plants do not belong to any particular genus and in some cases are an oddity within the family. Many silver leaved plants are found growing on limestone foundations and so are well suited to the limy conditions in my own garden, and although the colouring is usually better on lime, they can well do without it as long as the drainage is sufficiently sharp. Some of the plants which readily spring to mind are Artemisia and Helichrysum. Two varieties to consider are Helichrysum angustifolium (H. italicum) which has needle-like foliage and H. petiolatum with almost white, felty sprays of foliage which drape themselves elegantly in front of more upright subjects. These are as good for window boxes or tubs as they are for a raised bed or border. Artemisia splendens is a tufted perennial which makes a low clump if the leaders are kept clipped and contrasts well with bolder leaves of something like Artemisia stelleriana. This is a spreading perennial about 12" (30 cm) tall and a good front of the border subject. It has near white leaves similar in shape to those of a chrysanthemum, and will tolerate more shade and damp than the other types.
Artemisia alba 'Canescens' is one of my favourite plants but which I do not succeed in growing well. I have seen old gnarled plants of this lasting for a long time in some gardens, but have not found the place for it in my garden where it is truly happy. It looks so pretty when it forms a mound of silver filigree. Another filigree is Artemisia absinthium 'Lambrook Silver', selected by Margery Fish, but this is a much taller shrub and very suitable for cooling down hot-coloured perennials in a border or dividing two plants of the same colour but different shades, such as delphiniums and campanulas. This grows to about 3' (80 to 90 cm) and needs about 2' to 3' of space to develop well. Another graceful plant for a sheltered place and one I do not like to be without is Senecio leucostachys, usually described as a small shrub, but I find that by a wall it clambers up to 3' or 4' and interweaves prettily with other wall subjects. I have also seen it grown as a shrub at the end of a border. It does not like the wind and is rather brittle, but in a dry, sunny spot and tied in if necessary, it will give long and valuable service. It has pale creamy flowers in flat clusters which do not detract from the foliage in the least. This is silvery white and very finely cut.
Santolina is another shrub which should be considered if you want a mound of silver foliage. S. chamaecyparissus, the true Cotton Lavender, is a very underrated plant, and is often disliked because of its harsh mustard yellow flowers. I have a variety with pale lemon flowers and the shrub grows into a pleasing rounded shape.
It can become rather woody and oversized, but cuttings are so easy that it is a simple matter to have a few young plants to bring on and replace those which have become too big. This shrub grows to about 2' (60 cm) but there is a smaller one, called S. chamaecyparissus 'Nana' if required. One of the most often remarked upon silvers in my own garden is the Atriplex. There are two varieties, A. canescens and A. halimus. The latter is by far the better silver and is also good for cutting, lasting well if given the hot water treatment. It needs keeping trimmed to preserve a good shape in the border, but in a shrubbery it can be left to its own devices and is a lovely sight near old-fashioned roses, enhancing the purple pink colours handsomely. It usually attains about 4' (120 cm).
I have wandered away from the smaller plants in my enthusiasm for some of these larger lovely silvers, but I must mention the Dianthus family, whose clumps of foliage are so decorative even when the flowers have finished. They thrive in the dry conditions and are usually better if not grown on rich soil. It is impossible to mention them by name as there are so many beautiful cultivars, but there are large tufts such as the well-known untidy, fragrant 'Mrs. Sinkins' to tiny alpine miniatures suitable for the edges of a terrace. One favourite of mine is D. 'Elizabethan' a very old cultivar but seldom seen. Available from Elizabeth McGregor it has white petals with a dark maroon eye and rim.
Other small subjects to look out for are Geranium harveyi, G. argenteum and a potentilla with a creeping habit and very silvery leaves which I have not yet properly identified. Let me know if you can tell me what this is.
One final recommendation for the most superb shining silver is Convolvulus cneorum, a shrub with silky silver foliage and covered with white flowers in late May and June.This is an enhancement to any garden. It requires very sharp drainage and a sunny position to thrive, but when well-grown it will be much admired. A hole completely filled with grit will help you to succeed with this when planting it, as it is naturally a scree plant and cannot stand wet feet. It usually grows to about 18" (45 cm).
A border using blue and silver plants has always been in the back of my mind since I saw this combination some years ago, which demonstrated beautifully the use these silvers can be put to. It was composed of blue agapanthus, silver Artemisia 'Powis Castle' and silver leaved creamy flowered potentilla.
First published in the Wilts & Avon Group Newsletter, September 2011
and subsequently in Cornucopia Issue 30.
© Copyright for this article: Mary Hember
This article was taken from a copy of Cornucopia that was published in 2012. You could be reading these articles as they are published to a national audience, by subscribing to Cornucopia.