The colour blue

Sunday, 27 March 2016

Salvia guaranitica Large Form with Euryops pectinatus daisy in the background

Recently I saw the exhibition Blue: Alchemy of a Colour, at the National Gallery of Victoria International in Melbourne - an exploration of the two most historically important blue colourants: the mineral pigment cobalt (used in ceramics) and indigo, derived from the plant Indigofera tinctoria (used in textiles). Both substances were introduced to Europe in the 16th century. Chinese blue-and-white porcelain was highly prized, and its decorative patterns and compositions profoundly influenced European artwork. Indigo was used over the centuries to colour cloth through the use of tie-dying and wax resists (such as batik). The colour blue is associated with deities in Hinduism and Buddhism, and blue components of garments were thought to enhance the power of the wearers and protect them from evil forces. Blue material was also used for ceremonial clothes to show the rank of the wearer.

Borago officinalis: the herb borage

The beauty of the blue-and-white ceramics and textiles on display (many of them extremely ancient) reminded me of the timeless effectiveness of this crisp colour combination in gardens, and of my fondness for the colour blue in general. In fact, it is probably my favourite hue of all, both in the garden and out of it! I have always thought there was something 'celestial' about the colour; indeed, in Italian the word for sky-blue is celeste! As a child with an overactive imagination, I thought blue flowers were made from piece of the sky, or made by fairies!?

Blue is a 'cool' colour, and it suggests space and distance, as well as freshness and calmness - and perhaps even an element of melancholy. Hot colours such as red, orange and yellow can be tiring on the eyes after a while. It is hard to find flowers that are coloured pure blue: so many tilt towards the purple part of the colour wheel. However, blue retains its character when lightened with white or darkened with black, and I love all its shades and tints. It seems to me that blue flowers mix effortlessly with those of any other colour, enhancing each of them in different ways. Harmonious and dreamy with related cool colours such as violet, purple and soft pinks, blue makes hotter colours such as yellow and orange seem brighter and more excitingly vibrant when it sits side by side with them. I particularly like blue flowers nearby to golden or lime-green foliage, and I also enjoy seeing them with silver or purplish foliage for different effects. This week I wandered around my garden to identify some of my favourite blue flowers.

Browallia americana

Perhaps the bluest of all in my garden is the annual Browallia americana, a truly delightful little plant that entered my garden as a single wilted seedling pulled up by a kind friend from her garden. 'You'll never get rid of it', she remarked, in what sounded a vaguely ominous tone. And it's true; I now have it everywhere through my garden as it self-seeds madly, and I pull up a fair few every year - but I love it more than ever. The seedlings appear in spring and grows to about 30 cm or a little taller. The gorgeous bright blue flowers each with a tiny white eye complement every plant they decide to grow next to. Their ubiquity throughout my garden actually provides a uniting thread! They flower all through summer into autumn, and sometimes new ones appear at that time that carry on until spring. They can be cut back when they start to look straggly and they will rejuvenate. I only pull them out when they have utterly had it. Though they flower best in sun, they do grow quite well in part-shade.

Salvia sinaloensis

Salvias offer some of the bluest of blue flowers, but to my chagrin, I have found that the best of these belong to the most rampageous varieties (think Salvia uliginosa or Salvia guaranitica, including its seductive but wicked cultivar 'Black and Blue') or ones that don't grow that well in Sydney (apart from in the more elevated areas), such as the gorgeous Salvia patens. However, there are some good ones for Sydney, including shrubby Salvia guaranitica Large Form (a non-running type with blooms of a clear royal blue); Salvia sinaloensis, a groundcover with startlingly blue flowers held against purplish-tinged foliage; and Salvia 'Marine Blue', a tough shrublet which has its bright blue flowers from spring until the end of autumn. In general, these plants will do best in a sunny spot.

Ceratostigma willmottianum

A stunningly rich blue flower appearing now in the garden is that of small shrubby Ceratostigma, the so-called Chinese plumbago, which has a couple of species. The simple flowers are enhanced by the autumnal tints of orange and red that some of its own leaves develop at this time of year as the temperature falls. Like many shrubs from China, these are adaptable to cool and warmer climates alike. Actual Plumbago also has pretty blue flowers of different shades, but I am not a fan of this larger shrub, which tends to sucker and spread too much in Sydney gardens.

Hydrangea macrophylla, mophead form

Hydrangeas are another source of blue flowers - as long as you have an acidic soil in your garden: otherwise your flowers will be pink! This also applies to the evergreen cousin of the Hydrangea, called Dichroa, a taller shrub which has domed, clustered flowers in flushes. Sydney has one of the best climates in the world to grow these shrubs, which grow best in a shaded spot. I love all hydrangeas and enjoy their lovely blue flowers in vases through their main blooming period of early summer. There are so many variations in flower form and in the depth of the colour. Blue looks at its most cool in shade, so banks of blue hydrangeas under tall trees can provide a welcome oasis on a hot summer's day, especially if paired with some white flowers to enhance the effect even more.

Borage (Borago officinalis, pictured earlier in the blog) is another favourite of mine, with its clear-blue, star-shaped flowers. Like the Browallia it is a self-seeder; however, I don't mind weeding the extra ones out. I have also always loved the bright blue daisy flowers of Felicia amelloides, but it doesn't like my heavy garden soil and fades away before too long.

Hope everyone is enjoying the Easter break. I'd be interested to know some of your favourite blue flowers!

Reader Comments

  • By Janna 0 Monday, 28 March 2016

    That blue Hydrangea is just gorgeous; the prettiest of blues. I"ve always had pink ones, no matter how much aluminium I throw at them! Yes it does seem as if it is quite hard to change the colour. I actually don"t mind the pink look but as hydrangeas were aways blue in my parents" garden when I was growing up, that is what I always think of them as; the pictured hydrangea was grown from a cutting of one in their garden! Deirdre

  • By margaret 2122 Monday, 28 March 2016

    Thank you for the history of the colour blue - it is fascinating. I love blue in the garden, in all its hues. Like you, the browallia americana is a beautiful clear colour, wonderful in the garden, but unlike you, mine has not self-seeded, so each year, I battle to keep it for the next season. Next to this plant, my other favourite plant is the blue hydrangea, whether light or dark blue, it lights up the space. Sulphur and peat contribute to a dark colour. I"d be interested to try those tips on darkening the hydrangea colour. Thanks, Margaret. Deirdre

  • By Peta 2758 Monday, 28 March 2016

    Blue has always been my favourite garden colour - leaves included! A few years back I made a blue garden after 2 huge Eucalypts were hit by lightning, subsequently removed, and a new space provided. The garden is approximately 9 by 9 metres and chock full of plants. Here are some - Iris, blue of course, "Rozanne" geraniums, blue Boltonia, Penstemon, "Blue for You" Roses, all sorts of blue Salvias, Shastas, over 100 blue flowered bulbs including Crocus and Scilla, Convolvulus, Calibrachoa.... How wonderful, and you can grow the beautiful cold-climate blues as well! Deirdre

  • By Maxine 6026 Monday, 28 March 2016

    Browallia Americania sounds like a must have. I wonder if it will grow in Western Australian sand. I have a community verge strip on the main highway near my home I think this plant would look great among the marigolds and white vincas we have growing at the moment. Worth trying it; in my garden it even comes up (and thrives!) in cracks between pavers so I think it should be fine! Deirdre

  • By JAN 2130 Monday, 28 March 2016

    Love blue, and all the plants you mention. Perennial Ageratum still flowering, Noddng Violet finally looking good, Stokesia an old favourite, Blue Ginger stunning (or is that purple?), trying Octacanthus. For me, Salvia Uliginosa adds a wonderful softness, never been a problem. Like it "in-filling" among other plants which in turn support the long stems. Strays easily pulled out. Bonus w Borage is flowers are edible. Do agree Guaranitica is invasive and replacing it will require determination!

  • By James 2042 Monday, 28 March 2016

    I must be on trend - I too am exploring blue in the garden - inspired by the Ceratostigma plumbaginoides (ground cover form) that a neighbour was growing - I added Blue ginger and Evolvulus pilosus - flowers well in part shade. Blue, white and lime is the most serene combination. There have been failures and some I"m too scared to try - e.g.: Salvia patens - in the catalogue just looked too beautiful - I am pleased you say it doesn"t like Sydney..I await a Clematis Blue Belle from Tassy - brave? I too love white, blue and lime together. I have never had luck with Salvia patens but I think everything is worth a go, as sometimes there is a microclimate where something might thrive. My philosophy is that I will try something three times before I declare it unsuitable for my garden! Some clematis do grow well in Sydney; in general I think the viticella ones do best. But everything is worth trying. Deirdre

  • By Densey 2446 Monday, 28 March 2016

    I also love blue flowers - often hard to track down. A favourite blue shrub is Otacanthus caeruleus - Brazilian Snapdragon or Amazon Blue. I have grown it over many years as a foil for my pink/red/mauve pentases and salvias and like Pentas the flowers appear over many months. Another blue favourite of mine is the annual/biennial Chinese Forget-me-not, Cynoglossum (I think).It self seeds and I can"t have too much of its lovely flowers popping up here and there.Densey I too love Cynoglossum. I have tried Otocanthus as it is so gorgeous but cannot get it to survive winter here. Our winters are just a little too cold for it. I think it does better closer to the coast or in a protected position in the garden. I should try it again! Deirdre

  • By Carole 2230 Monday, 28 March 2016

    Deidre, I too love blue. Love borage but I"m allergic to it :-( A particular favourite is clerodendron ugandense. I also love forget-me-nots (myosotis) although I haven"t planted them in my current garden because of the "sticky" seeds and I"m not sure how they would like the Sydney climate. I am resolved to try the browallia and I"ve ordered seeds. Hydrangea just does not like my garden either in the ground or in a pot, sad. Even ordinary plumbago succumbed to drought conditions here in the past. Forget-me-nots grow well in Sydney - they will self-seed greatly! I also like the Clerodendron you mention. Shame about the hydrangeas not liking your garden. Deirdre

  • By Margaret 3002 Monday, 28 March 2016

    Thankyou for great description of blue plants. Have ordered Browallia and Rozanne geranium. Have another blue one but don"t know it"s name. I have Nigella, Iris and Campanula. Also salvias both short and tall. Will check other plants mentioned in your article and those mentioned by fellow gardeners. It could be a late night! Thanks Deidrre. Margaret Thanks, Margaret. Nigella is another lovely self-seeding annual with pretty blue flowers. Not many Campanula grow well for me but C. poscharskyana, a groundcover, has very pretty pale blue flowers in spring. And Geranium Rozanne is the best species geranium for Sydney gardens, I think! Deirdre

  • By Pam 2159 Monday, 28 March 2016

    Deirdre, I love blue in the garden too - part of my front garden was planned to be blue, white and yellow, although other colours have moved in over the years. In shady areas the more tropical shrub Eranthemum pulchellum has clusters of pale blue flowers in early Spring. The bright blue flowers of the bulb Aristea are lovely, but it seeds too much and becomes feral. Smaller dark blue Agapanthus are lovely in Summer. A driveway lined with blue Agapanthus looks fresh and cool in Summer. Thanks, Pam. I love that Eranthemum shrub is spring! Interestingly, I have never had a single self-seedling from Aristea! It is strange how in some gardens certain plants self-seed a lot yet they do not do it in other gardens in the same area! I love Agapanthus too and there are some lovely deep blue cultivars around these days -- but I like the milky-blue ones too! Deirdre

  • By Helen 7256 Tuesday, 29 March 2016

    I haven"t always been a big fan of blue, but it sets off other colours so wonderfully! Favourites at the moment are Salvia ulignosa and S muirii ( both flower all summer and are still going. salvia guarantica "Sky Blue" ans Salvia "Black and Blue are new ones for me this year - they had a hard winter and are just coming into flower now - I plan to relocate to a more sheltered spot over the winter. Have just bought Salvia somalensis and kooking forward to its pale blue flowers! Thanks, Helen. Sounds pretty. Deirdre

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