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Cornucopia - How to stay cool in Summer

How to stay cool in Summer
Janet Dolling

Early this summer I visited some lovely gardens with very pale colour schemes. Some had a good framework of variegated or lime green shrubs to carry them through the year but others seemed heavily dependent on once-flowering geraniums and to have little left of interest in shaded areas where spring flowers had been. I worried for a while over what could keep this colour scheme going and started a list of possible pale plants. It got quite extensive, especially when I came to the hostas, phlox and michaelmas daisies, but here are a few, perhaps less well known plants, that could be of interest.

The hardest part of any garden to keep going through the summer is dry shade, its natural flora copes by flowering before the trees take all of the water from the soil. There are a few very nice shrubs that will light up this situation throughout the year. Pittosporum tenuifolium 'Variegatum' (or another of its many cultivars) will grow well, even in the dust-dry litter under conifers. The variegated cultivars of Euonymus fortunei will also grow in dry shade. There is one glamorous shrub that will grow in dry or well-drained soil, in sun or shade, and flower from August to May. The shrub is Coronilla valentina subsp. glauca 'Citrina' and it fits the colour scheme perfectly having blue-grey leaves and lemon flowers plus scent.

The value of tough plants such as Brunnera macrophylla can be extended by using the silvered cultivar 'Jack Frost'; it seems just as easy to grow and has paler blue flowers. The obvious space fillers in shade are ferns and Polystichum setiferum supplies a huge choice of light and lacy cultivars that can cope with dry soil. The ferns with paler coloured fronds do need a bit more moisture. Dryopteris wallichiana prefers neutral to acid soil. Eventually a big fern, its young fronds are bright yellow green. Athyrium niponicum var. pictum with its pink flushed silver fronds is well known now but A. otophorum is my favourite pale fern with creamy-green young fronds maturing to light green with a maroon rachis.

Lilies flower later than most bulbs and Lilium martagon, with its pink or white flowers in June and early July, will grow in quite dry shade or in the open border. Later in July the white and gold flowers of 'Lady Alice' or 'Bright Star' could replace them. These tall hybrids of Lilium henryi will grow anywhere. There are other woodland lilies; pale yellow, scented L. monadelphum and white, pink speckled L. lankongense and L. duchartrei. These are often available from the HPS seed list and germinate easily. If perfume is required, Lilium regale will produce its pink-backed white trumpets in all but the wettest or driest soils.

For the edges of shady areas there are three exquisite campanula relatives; C. 'Burghaltii' produces many 60 cm stems from a small leafy base, each bearing a succession of long, pale smoky mauve bells from June onwards, as long as it is not too dry; C. ossetica is a low creeping plant with pale blue bells and a very long flowering season; Codonopsis clematidea, a delicate plant with grey-green leaves, has the palest blue bells with a multicoloured pattern inside. There are many other woodland campanulas in this colour range, some quite tall. Nepeta govaniana with its airy spikes of lemon flowers also suits this situation.

There is a very useful variegated sedge, Carex morrowii 'Fisher’s Form', which makes spiky mounds of pale yellow striped leaves, even in dry shade. Achillea nobilis subsp. neilreichii has cream flowers and grey filigree foliage and will also grow in this situation. Both these plants provide a good contrast to dark ferns.

In August the small flowers of Cyclamen hederifolium come to the rescue, followed by their beautifully patterned leaves and in September the paler cultivars of Colchicum autumnale and C. speciosum would brighten the scene. During autumn and winter, Arum italicum makes a huge contribution, especially if you find a ‘well-marbled’ variety.

There are geraniums to fit this colour scheme that will flower from mid-summer on into early autumn in sun or light shade. Geranium wallichianum 'Buxton’s Variety' has nice marbled leaves and puts out long stems bearing light blue, white-centred flowers. The hybrid G. x oxonianum will grow almost anywhere and flower continuously, if not totally desiccated. The coolest pinks are probably 'Old Rose' and 'Rose Clair' but even these might be more refined accompanied by the pale green summer hyacinth, Galtonia viridiflora, or lime green nicotianas. The other long-flowering geraniums need full sun and good drainage. Christopher Lloyd edged his long border with G. x riversleaianum 'Russell Prichard', it has dazzling magenta flowers. The sister variety 'Mavis Simpson' has nice grey-green leaves and soft pink flowers on stems that lengthen through the summer. Geranium traversii var. elegans and its hybrids such as 'Sea Pink' also have grey shaded leaves but the flowers are palest pink. This species can be short lived but usually provides a few offspring.

Hemerocallis will grow in sun or part shade but the pink and cream flowered cultivars seem to need some moisture in the soil to do well. Young hemerocallis leaves make good, bright green tussocks in early summer as a foil for other flowers. H. 'Stoke Poges' is a pleasing shade of pink. In full sun agapanthus also provide a handsome clump of leaves and flower usefully late. Dark blue and purple varieties are much promoted but there are some lovely pale ones too. 'Blue Moon' has large heads of greyed pale blue flowers and is fully hardy here; 'Windsor Grey' has less blue in its colouring; 'Gayle’s Lilac' is also nice and grows well. For a contrastng plant shape aconitums could do well. For July there is Aconitum x cammarum 'Bicolor' and its variety 'Eleonara' with 60 cm spikes of white, hooded flowers, flushed with blue. In August the slightly taller 'Stainless Steel' flowers and in September the beautiful, 1 m plus A. carmichaelii Wilsonii group 'Spätlese' takes over. Both the later varieties have very pale blue flowers.

In the open border there are some excellent grasses to add structure to the design. Best value probably comes from Calamagrostis x acutiflora 'Overdam'. It has pink-shaded white variegated leaves in spring and early summer topped by airy mauve-pink flowers on tall stalks which last until Autumn, eventually fading to buff. Miscanthus sinensis 'Morning Light' has narrow, white-edged leaves which look like a pale fountain by July; it has soft red flowers fading to silver in autumn. The more imposing M. sinensis var. condensatus 'Cosmopolitan' has broad, white striped leaves. It gets to about 2 m tall but seldom flowers for me. Piet Oudolf uses the lime-green, tussock forming Sesleria autumnalis as an effective cooler in his ‘meadow’ of vivid flowers at Scampston.

Polemoniums tend to get a bad name for themselves by seeding around, but there are good sterile hybrids which flower from June through to late summer. P. 'Hopleys' is 60 cm tall with white flowers, shaded purple; P. 'Sonia’s Bluebell' and P. 'Northern Lights' are pale blue, a bit shorter and will tolerate some shade. The only pale penstemon I grow is the old variety 'Pennington Gem'. It is a tall, strong-stemmed and long-lived plant with elegant, soft pink, white-throated bells.

The effectiveness of sedums is continuous from their emerging, succulent leaves in spring to their heads of pale flower buds, then late summer flowers and seed heads that last through autumn. Most of the grey-green leaved kinds have brilliant pink flowers but Sedum 'Joyce Henderson', a tallish variety, has large, flat heads of creamy pink flowers. Sedum telephium subsp. fabaria is different; it has neatly toothed leaves and many smaller flower heads that are smoky mauve in bud, for many weeks before the flowers open. S. telephium subsp. ruprechtii is a lovely plant, with its dove grey leaves and cream flowers, but it needs dead heading or it will seed around. The old cultivar, 'Herbstfreude', has put itself into a dry bed under trees. It is taller than usual and its flowers are a paler pink! Lots of eryngiums would fit into this colour scheme and Eryngium giganteum 'Miss Wilmott’s Ghost' is positively chilling with its silvery white leaves and bracts. To add more prickly silhouettes of a larger size there are two non-invasive globe thistles, both with ice-blue flowers. Echinops maracandicus is 2 m tall and quite narrow in outline; E. sphaerocephalus 'Arctic Glow' is a much broader plant and is 1 m tall.

By now the garden will be well into phlox time and the earliest michaelmas daisies will be flowering. The choice of good mildew-resistant varieties is now huge so I will leave you to select the coolest colours.

First published in the East Yorkshire Group Newsletter, November 2009
and subsequently in Cornucopia Issue 27.
© Copyright for this article: Janet Dolling

This article was taken from a copy of Cornucopia that was published in 2011. You could be reading these articles as they are published to a national audience, by subscribing to Cornucopia.


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