September, a transitional month in so many ways, marks the gilded gateway from one season to another, a natural changing of the guard. Many plants inevitably start to elegantly fade from sight, making those that continue to shine brightly into late autumn all the more precious, their beauty amplified by the fact that they’re the welcome exceptions to the rule.
Among the indisputable stars of this invaluable group of late-flowering plants are many kinds of ornamental salvias, a genus to which a horde of excellent new garden-worthy varieties have been added by expert plant breeders in recent years. They are equally suitable for a traditional flower border or a contemporary gravel garden as well as for container growing, and many are exceptionally long-flowering as well as impressively pollinator friendly. They’re also joyfully colourful with an ability to add glorious pops of brilliant, almost subtropical glimmer to any flower bed or pot display.
Examples include the Wishes series of herbaceous perennial salvias such as the magenta-flowered S. ‘Love & Wishes’, which blooms from June until the first harsh frosts, and its close relative, the equally long-flowering ‘Wendy’s Wish’, as well as the tall, inky-purple S. ‘Amistad’ and its pink-magenta flowered sister, S. ‘Pink Amistad’. Another is Salvia curviflora, a spectacular species native to Mexico, with tall stems of tubular, lipstick-pink flowers through summer and autumn. Yet another is Salvia patens, commonly known as gentian sage, a species prized for its electric-blue, pollinator-friendly flowers and long-flowering period. Recommended varieties include Salvia patens ‘Guanojuato’ and Salvia patens ‘Blue Angel’, the latter of which can be raised from seed sown in spring with bottom heat under cover, for transplanting out into the garden in early summer. So can the glorious Salvia sclarea var. turkestanica ‘Vatican Pink’, whose tall spikes of pink and white flowers are also excellent for cutting.
With the exception of that last one, which is fully hardy, all the above are classed as borderline hardy/half-hardy, which means that in cooler, wetter parts of the country they won’t reliably overwinter outdoors and should instead be brought under cover of an unheated glasshouse or polytunnel for replanting again outdoors the following summer. But in milder, sheltered Irish gardens, they’ll do just fine in an average winter where the temperature doesn’t dip below minus-five degrees. Just bear in mind that rather than low temperatures, what’s most essential to these sun-loving, drought-tolerant varieties of ornamental sage is a free-draining soil that doesn’t ever become waterlogged in winter.
Salvia ‘Cerro Potosí’
In my own garden in Laois, I grow several borderline hardy varieties in a sunny, sheltered, very free-draining spot close to the base of a south-facing stone wall, where they survived several sustained cold spells last winter unscathed.
That same need for a moist but free-draining, not overly fertile soil is true of many of their shrubby, equally long-flowering but hardier cousins, such as the red-and-white, clump-forming, semi-evergreen Salvia ‘Hot Lips’, which can be seen in many Irish gardens flowering its socks off from early summer until November. Perfect for a sunny, raised bed or large pot, it reaches an average height and spread of one metre. To keep it compact and floriferous, an annual light trim in spring is recommended. It’s a similar story for crimson-flowered Salvia ‘Makris’; cerise-pink Salvia ‘Cerro Potosi’; scarlet-flowered ‘Royal Bumble’ and plummy-flowered Salvia ‘Nachtvlinder’.
Their beauty aside, these shrubby salvias also play a beneficial role in the garden in terms of boosting plant health. This is a result of the plants’ resinous-smelling foliage, a pleasant aroma that their leaves release on warm sunny days and which is naturally rich in anti-fungal sulphur. For this reason, the well-known British gardener Sarah Raven suggests using these lower-growing, shrubby, clump-forming types as companion planting beneath roses, where they’ve been proven to help suppress common diseases such as blackspot and rust.
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At the other end of the hardiness spectrum is the new Salgoon series of salvias, which will only reliably overwinter in the mildest, most sheltered of Irish gardens where temperatures don’t dip below minus-one degree. Even so, in cooler gardens it’s well worth experimenting with planting these in an exceptionally sheltered, free-draining spot where they’ll be protected from the worst of winter cold. As mentioned above, another alternative is to lift the plants in autumn and overwinter under cover in an unheated glasshouse or polytunnel, where they can be given further protection in the shape of a couple of layers of horticultural fleece during any unusually cold spells. Classed as herbaceous perennials, this hugely decorative, floriferous group includes the purple-flowered Salvia ‘Spencer Lake’; lavender-blue Salvia ‘Lake Como’; and the fruity-pink Salvia ‘Strawberry Lake’.
A hummingbird hawk moth feeds on salvia in a garden. Photograph: Dan Kitwood/Getty Images
Along with their many obvious charms, one of the other great joys of growing salvias is how easily these hugely decorative plants can be propagated from cuttings taken in late spring/early summer. Placed in small pots of horticultural grit or a good-quality seed and cuttings compost lightened with generous additions of vermiculite, they will often root in a matter of mere weeks, glorious proof of the boundless generosity of nature.
To see many of the above as well as other choice varieties of salvia in bloom such as S. involucrata; S. fulgens and S. confertiflora, I highly recommend a visit to Hunting Brook, the west Wicklow garden of Jimi Blake, Ireland’s unofficial king of salvias. He grows them in a multitude of brilliantly colourful, experimental, creative combinations, often alongside dahlias, another floriferous genus that’s one of the enduringly bright stars of the autumn garden. If you thought the latter was solely about foliage and its pretty hues of russet, copper and gold, then you’re in for a very pleasant surprise.
This week in the gardenMany varieties of tree fruit including apples, plums and pears become ready for harvesting over the coming week. Try to do this before the fruit falls from the tree, which not only can cause bruising and subsequent problems with decay as well as disease, but also problems with bees and wasps being attracted to the damaged or overripe fruit.A combination of low rainfall and high temperatures in recent months has resulted in very dry soils in almost all parts of the country and means that late-cropping vegetables such as squash and pumpkin plants may need to be hand-watered over the coming weeks to prevent a check in growth and damage to the fruit.Dates for your diarySaturday, August 30th, 3pm-5pm: St Patrick’s Primary School, Church Road, Greystones, Co Wicklow, Delgany & District Horticultural Society’s annual Dahlia Show will take place. See the society’s Facebook page for further details. Also Saturday, August 30th (2.30pm-4.30pm): St Nessan’s Community School, Baldoyle, Dublin, D13 F6N3, Howth & Sutton Horticultural Society Autumn Show and Plant Sale with exhibits, plant sales and garden tools for sale, refreshments and raffle.
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