Have you ever noticed how the best summer gardens seem to shimmer, a quality that’s almost impossible to define but is inextricably linked to the kinds of plants used? Like the gilt on a beautiful picture frame, they give a burnished, almost luminous air to the planting so that it softly glows.
The classic summer shimmer plant, of course, is the decorative grass known as golden oats or Stipa gigantea, a majestic semi-evergreen species that forms a large tuft of slender arching leaves from which tall panicles of golden, oat-like flowers gracefully emerge in early summer. Situated in a bright, warm, open spot where they are backlit by sunlight, the effect is mesmerising, especially when those tall flower stems are softly shaken by gentle summer breezes so that each tiny inflorescence quivers.
Not only is it memorably beautiful, but it’s an impressively long-lasting display too, enduring well into late autumn and providing the perfect veil-like backdrop to late-flowering perennials such as ornamental sages, Japanese anemones, asters, helenium, eupatorium, echinacea, sedums and Verbena bonariensis.
Difficult to grow? Not a bit of it. Instead the gauzy, delicate beauty of its shimmering flowers belies this ornamental grass’s impressively tough, resilient nature. Native to Spain, Stipa gigantea is drought-tolerant and will happily grow in both full sun and light shade as long as it’s given a free-draining soil, slowly forming dense semi-evergreen hummocks of foliage that give some structure to the winter garden. Plants in full flower reach an average height and spread of 2m x 1.2m, taller again (up to 2.5m), in the case of the glorious variety known as Stipa ‘Gold Fontaene’, but are never obtrusive, making it a great choice for small gardens.
Many other ornamental grasses share Stipa gigantea’s ability to make a summer border glisten, albeit not on the same impressive scale. Examples include squirrel tail grass or Hordeum jubatum, whose delicately tufted, rose-gold flower-heads look like they’re made from threads of the finest silk. A short-lived, compact perennial grass that likes a sheltered position in full sun and a free-draining soil, it self-seeds when happy, something I recently discovered to my delight in my own garden. Just take care not to accidentally weed out the baby plants in spring when they emerge, which is all too easy to do.
Another ornamental grass guaranteed to gild a summer garden is the feathertop grass, or Pennisetum villosum ‘Cream Falls’, whose fluffy, silver flowers have a luminous beauty capable of transforming the most mundane planting scheme. Technically an evergreen perennial, it needs a warm, sheltered position to properly overwinter but can also be treated as a fast-growing, half-hardy annual easily raised from seed sowed in spring under cover.
In this case, space the baby plants very closely together to that they’ll quickly form an attractive clump. Young children in particular find this clump-forming, medium-sized, semi-evergreen perennial’s soft, bottlebrush flowers endlessly fascinating, rarely resisting the urge to run their fingers through them.
Purple moor grass, or Molinia caerulea, is another ornamental grass with the same magical, luminous quality, which is why garden designers love to use this supremely hardy, deciduous, long-flowering perennial threaded through summer borders. Happy in full sun or light shade, it likes a moist but free-draining, preferably acidic, soil. Many very garden-worthy cultivars are available including Molina ‘Heidebraut’, M. ‘Transparent’, M. ‘Edith Dudszus’ and M. ‘Moorflamme’, all of which also provide wonderful autumn colour as their flowers darken with age. Height and spread varies according to the particular cultivar, but even the tallest have that precious, semi-transparent quality that allows light to easily filter through their airy flowers and foliage.
Ornamental grasses aside, certain perennials share the same magical ability to leaven and lighten the summer garden. One of the best is bowman’s root, or Gillenia trifoliate, whose airy, graceful clouds of starry pale flowers are borne on slender wine-coloured stems in early summer, followed by ornamental seed heads and a very pretty display of autumn foliage. Best in full sun and a damp, fertile, free-draining soil, this hardy, resilient herbaceous perennial should be much more widely-grown and also makes a fine cut-flower.
Another perennial that I love for its ability to float through a summer border is the lesser calamint, or Calamintha nepeta ‘Blue Cloud’, an elegant relative of catmint. Hardy and clump-forming with tiny, highly aromatic leaves, its small pale flowers are beloved by bees and other pollinating insects. Grown in a warm, sunny spot in the flower or gravel garden, it forms a semi-transparent haze of very pale lilac flowers from high summer right through into autumn and combines beautifully with other heat-loving, late flowering perennials.
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I’d also hate to be without Oenothera lindheimeri (formerly known as Gaura lindheimeri), a stalwart of my garden from midsummer until the first harsh frosts of autumn. Now a few years old, my plants are the variety known as ‘The Bride’, propagated from a packet of seed I sowed under cover in late spring and then planted out into the garden in summer.
This exceptionally long-flowering, drought-tolerant, resilient perennial isn’t often found in standard Irish garden centres, I suspect because it doesn’t have what those in the business describe as “pot appeal”. However, grown in the ground where it has space to spread itself about, it’s a marvellously useful plant for a sunny summer border, producing a cloud of soft white flowers tinged with pink that shimmer in the summer sun.
‘The Bride’ and ‘Whirling Butterflies’ are the two classic and most commonly available varieties, but others include the bright pink ‘Siskiyou Pink’, and the newly-introduced bi-coloured ‘Rosyjane’ (pink and white flowers). All reach an average height and spread of 1m x 1.5m. I grow them in a sunny, very free-draining border in my garden along with the aforementioned Stipa gigantea, Pennisetum ‘Cream Falls’, Hordeum jubatum, Verbena bonariensis, Erigeron karvinskianus, achillea, verbascum, ammi and herbaceous potentilla. Even on the wettest and dreariest of Irish summer days, it’s a combination that shines.
This week in the garden
The torrential downpours of recent weeks have left many taller growing annuals and perennials looking bedraggled and forlorn. So, take advantage of any dry spells to cut back damaged stems and deadhead plants, before providing some support in the shape of a cat’s cradle of canes and string to help prevent further damage in the months ahead. This is especially important for plants with large fleshy stems such as dahlias, sweet pea and gladioli, or top-heavy species such as cosmos.
Those same wet, humid weather conditions are also very favourable for the spread of potato blight. Signs of this destructive fungal disease include poor or stunted growth, and dark-brown patches surrounded by a pale “halo”, visible on wilting foliage and stems. If blight hits your crop, then quickly cut stems back to ground level and bag and dispose of them off-site
Dates for your diary
On Sunday, July 16th, (11am-5pm), at June Blake’s Garden, Tinode, in Blessington, Co Wicklow, there will be a celebration of the opening of this wonderful Wicklow garden’s recently restored “Grinding House” with an inaugural exhibition of the work of Wicklow artists Bob Lynn and Trevor Geoghegan. The garden is simultaneously celebrating the beauty of the dahlia season and its outstanding collection of more than 110 specie-type dahlias raised by owner June Blake from seed. See juneblake.ie
On Saturday, July 22nd, (11am-5pm), Belvedere House Unusual Plant Fair, in Mullingar, Co Westmeath, will take place with plant stalls by many small Irish specialist nurseries. There will also be talks by Irish gardeners Jimi Blake of Hunting Brook Gardens and Paul Smyth of RHSI Bellefield, plus music, food and entertainment. See belvedere-house.ie
