Embrace the summertime blues in your French garden

I get the gardening blues. It is not just hydrangeas but a whole range of blues that I love. Smoky blues, mauvey blues, glaucous (grey) blues but especially the true blues, which are rarer than you think. 

Blue is a wonderful colour in the garden because it associates with everything. There isn’t another colour that won’t look good with it and building a bed with all shades of blue is beautiful.

Although I use quite a lot of blue in my spring pots (muscari, iris, blue primroses, scilla and violas) summer allows for much more. There are blue shrubs such as ceanothus (there are all sorts of blues from the palest baby blue through to a really dark purply blue), caryopteris and delicate harebell-flowered sollya heterophylla but don’t be fooled by lurid colours in mail order catalogues.

There still is not a truly blue rose (it’s a greyish pink) and many garden hibiscus, buddleia or lilacs are not blue but quite pinkish mauve, whatever their oversaturated photographs show. Both plumbago and false plumbago (ceratosigma) have fabulous blue flowers.

Actual plumbago is frost tender and I keep mine in pots, bringing them under cover for the winter. The blue is pale but intense. It glows in the dusk. Well-looked after (dead-headed and fed) it will last many years in a container and you can easily take cuttings or layer to make more plants.

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Ceratosigma is hardy and will spread easily in the border if it’s happy. The flower shape is the same but it’s a bright, deeper blue which contrasts well with the foliage. A quick trim in spring is all it needs. You can propagate by cutting off pieces of rooted stem which run from the main plant.

Mine is bedfellows with two different amsonias – these blue flowered plants ought to be better known. The willow-leaved one’s foliage turns golden in autumn. The flowers are clusters of tiny stars. Some are an unusual almost light turquoise. Other plants with this same delicate shade are the sadly not very long-lived tweedia which fountains out of its pot and the shade-loving corydalis flexuosa. I don’t have the right conditions for it nor the fabulous shot-silk blue Himalayan poppy (meconopsis). I have tried, more than once. Beautiful as they are, I have to admit defeat.

I do keep trying with delphiniums because those towering spires of all shades of blue are just unrivalled. 

I now stick to annual lupins as the Russell hybrids never seem to establish here. The flowers look dip-dyed in ink, shaded from deepest darkest blue to the lightest sky blue.

A similar flower shape is baptisia australis (false indigo) – I planted mine, full of hope, in the blue border only for it to flower pure white. It’s been divided and rehomed in the white border and I have yet to replace it.

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Salvias deserve a paragraph of their own as there are so many gorgeous blues. The small flowered salvia jamensis will give you colour all summer. Find a specialist like Bernard Lacrouts or Les Senteurs du Quercy and you will find blues of every hue. Garden centres tend to just have the obvious ones.

Look, too, at the tall salvia guaraniticas – ‘Costa Rica’ is an electric blue and is perfectly hardy in my garden and also ‘Black and Blue’. Salvia uliginosa is otherwise known as the bog sage. I planted it by the pond and it sulked. On a trip up in the Pyrenees I saw it growing in profusion by the side of the road, in full sun, by rocky outcrops. I went home, dug it up and transplanted it to the front of the blue border – despite its height – and it has been happy for years.

Its airy structure and bright blue flowers, much loved by bees, are an essential part of the summer garden as are salvia patens ‘Cambridge Blue’ which must be planted in my terrace pots.

‘Cambridge Blue’ is also found among lobelias, a paler version than the more common but still very useful edging or container plant. Most people treat them as annuals but with a little protection they will survive. 

Lots of ‘disposable’ plants can be kept: Felicia (known in France as Agathe) is a mauvey blue daisy, laurentia or isotoma (a scented star-shaped flower), brachyscomes (Swan River daisies). My super blue is anagallis or, recently seen as, lysimachia monelli sold in France as mouron.

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A relative of scarlet pimpernel, its incredible depth of colour is set off by tiny dots of cerise and yellow in the eye of each flower.

It too is a perennial treated as an annual. Grow from seed or order plug plants (mini mottes) in early spring.

Morning glory ‘Heavenly Blue’ can be easily grown from seed every year and can smother a fence in bright blue trumpets every day. Linum ‘Heavenly Blue’ is flax which can be sown betwixt and between other plants, just like nigella or cornflowers.

For the price of a coffee you can have a whole patch of the bluest blue and then save the seeds and start again next summer.

There ain’t no cure for the summertime blues, as the song goes.