"The bluest of the blues"

I love rich blue flowers!
Sunday, 24 November 2019     

Close-up of Salvia guaranitica Large Form with Canna Striata leaf

Lately I've been admiring some of the most startling blue-flowered salvias in my garden. I think salvias do have some of the most brilliant blue flowers in the plant kingdom. Blue has always been my favourite colour and I sometimes wonder if this is why I became so enchanted with salvias in my younger gardening years, a love that endures to this day. There are salvias of all shades of blue - from pale baby blue, sky-blue, violet-blue, midnight-blue, purple-blue and azure-blue to name just a few, but I particularly adore ones with royal blue flowers (though colour labels are notoriously tricky in themselves and can mean different things to different people!): to me this is the bluest of the blues. So many of the other flowers of this colour - such as delphiniums, gentians, clematis and grape hyacinths - don't thrive well in our Sydney gardens (apart from in the cooler, more elevated suburbs), but salvias do very well!

My obsession with this colour led me to be seduced early on in my gardening journey by a truly wicked salvia: Salvia guaranitica - which sported flowers of this hue. How I loved it! Then (like many other gardeners who had been similarly beguiled), I discovered that it is a rampantly spreading plant, multiplying via large underground tubers that are very hard to get rid of. Eventually, I discovered a version of it known simply as Salvia guaranitica 'Large Form' (ht 1.3 m) and it flowers just as well as the scary one but is definitely non-invasive. It is an excellent long bloomer in my garden, from late spring until early winter. It is pretty with any other flower colour: white, yellow, orange, pink, cerise, lime (such as Nicotiana langsdorffii) as well as lime or gold foliage, either plain or variegated. It is best in full sun, but in hot areas it will enjoy some afternoon shade.

A plant new to me this year is Salvia sagittata 'Mosquito'. It has dainty 'true blue' flowers on black stems, and large, felted, arrow-shaped leaves. It is found in the wild at very high elevations in the Andes. It is frost-sensitive, suggesting it comes from the warmer parts of that region. It grows around 1-1.5 m tall in Sydney and flowers in summer and autumn. It flourishes best in full sun and is really a gorgeous plant, the flowers seeming to float in mid-air above the beautiful foliage.

Salvia sinaloensis is a low-growing plant from Mexico with one of the bluest of all salvia flowers. It spreads by underground runners to form a thick, ground-covering clump (but I don't regard it as invasive). The dainty flowers will soon appear on upright stems (ht 25 cm) and continue on through summer. The leaves can take on purplish tints if grown in full sun, but it does also do well in light shade. It appreciates watering during dry times. It makes a good underplanting for yellow or lime-green blooms, such as those of Kniphofia 'Lime Glow' or Justicia brandegeeana.

Looking beyond salvias, other plants that have brilliant blue flowers in my garden at the moment include Neomarica caerulea, a rhizomatous plant from Brazil with tall, attractive fans of evergreen architectural foliage (ht to 1 m). Its exquisite iris-like flowers, coloured the most brilliant blue, are appearing now (the photo doesn't do justice to their blueness!). Each lasts for but one day but they continue to open over several weeks. The flowers look particularly stunning when paired with nearby cerise blooms, such as those of Canna or Dahlia, or with silvery foliage such as that of Plectranthus argentatus. Neomarica caerulea thrives best in a sunny, well-drained spot with good soil, but is tough once it is established. Another rhizomatous plant that has variants with brilliant blue flowers is the good old Agapanthus, which is just coming into bloom now. The cultivars 'Electric Blue' (ht 75-90 cm) and 'Guilfoyle' (ht 1.5 m) are two I grow with rich blue flowers, but there are many more available these days.

Amongst annual plants in my garden, the most stunning blue flowers perhaps belong to Browallia americana, an easy-to-grow bushy annual from tropical South America (ht 30-60 cm), which has a mass of starry flowers in summer and autumn. It grows best in sun but will tolerate some shade; it grows in most soils. It is rarely seen for sale: if you are able to obtain even a single seedling from the garden of someone who grows it, you will have it forever. I started with one such lone plant given to me by a kind friend, and now have literally hundreds of them coming up each spring. They obligingly fill in any spare spaces in the garden, without swamping surrounding plants. Annual Lobelia erinus is another plant that has lovely rich-blue variants, and I have grown it in a pot recent times.

I'd love to hear about your favourite blue flowers!

 Reader Comments

1/9  Suzanne - 2073 (Zone:10 - Warm Temperate) Monday, 25 November 2019

Thanks for your blog Deirdre, I also love blue in my garden, one of my favourites being Salvia "Marine Blue" which has performed well in my garden for about 15 years. I like its small grey foliage, compact form and lovely on going blue flowers. My other favourite is the climber Petrea volubilis, another good performing and pretty oldie looking wonderful at present. Suzanne I love both those plants, too. "Marine Blue" is a rich colour and flowers so long; it is tough too. Deirdre

2/9  Hilary - 3795 (Zone:10 - Mediteranean) Monday, 25 November 2019

I have forgotten the name of my glorious Blue Salvia. About 1-1.5 metres, tends to be straggly, not overly invasive, flowers similar to the photos, but bracts of about 15cm hanging. Colour: Purple more than royal blue. We are in a cool, frost prone area in Melbourne, with hot summer sun, so for protection it is in a shaded spot, and I prune it back after flowering. It makes a fabulous contrast to a spreading Melaleuca bus, late hanging-on Hellebores, and soft blue low Salvias Hilary. It sounds a good one, Hilary! Deirdre

3/9  Hilary - 3795 (Zone:10 - Mediteranean) Monday, 25 November 2019

Thinking of Blue Flowers, I also have a few forms of the native Leucadendron, which I believe is a West Australian origin plant, needs sandier, well draining soils - which mine is not!! - but I"ve managed to use it as a ground cover close to a flight of steps. Also as a spot of brilliance among a rockery. Hilary That flower is gorgeous. Alas I will never be able to grow it but have enjoyed seeing it growing elsewhere. Deirdre

4/9  Catherine - 2130 (Zone:10 - Warm Temperate) Monday, 25 November 2019

I love borage flowers too for their rich blue colour...and you can make soup with the leaves! Yes, borage is beautiful. It pops up here and there in my garden each spring. Deirdre

5/9  Annie - 3677 (Zone:11B - Arid) Monday, 25 November 2019

In every garden Ive had, Ive managed to find a Ceratostigma to plant. Living in north-east Victoria I appreciate its resilience, but even more its small flowers of bright blue. It is low growing, and deciduous, which has led to obliteration in one garden when it fell victim to over-zealous weeding! In my present garden I have C. plumbagonoides, a low spreading ground- cover, and C. griffithii. Also, I do love Brunfelsia, (Yesterday, Today and Tomorrow). Thanks Deirdre. Ceratostigma is a wonderful plant and I intended to include it in the blog but ran out of space -- so thank you for mentioning it. It is a glorious colour and I find it grows well in semi-shaded spots as well as in sun. The leaves can take on pretty tints in autumn, too. Deirdre

6/9  Valerie - 2121 (Zone:10 - Warm Temperate) Monday, 25 November 2019

Thanks for mentioning blue flowers. They do look stunning in the garden and just about any other plant complements them. Here there are Agapanthus, Plumbago, Convolvulus, Evolvulus and Salvia "African Sky", which is a heavenly blue. Although something ate most of the "African Sky" flowers overnight leaving just a couple on each stem - maybe a very hungry insect or two! This has not happened before so I guess this shows how the drought is affecting plants beyond the water problem.What a shame about the African Sky flowers. They are a lovely colour. Deirdre

7/9  Maureen - 2118 (Zone:10 - Warm Temperate) Monday, 25 November 2019

Just love blue flowers and right now just have three stems of BRILLANTAISIA subulugarica which I originally believed was a ginormous Salvia judging by its square stem but actually in the Acanthaceae group. I cut it right down last year as it really was a giant!! I love that plant as it blooms for months on end. But yes it does need hard pruning in August --I cut mine almost to the ground. Deirdre

8/9  Carole - 2230 (Zone:10 - Warm Temperate) Monday, 25 November 2019

I too love the blue flowers. Although currently I have only dichorisandra thyrsiflora which I initially bought as a cutting from a fund raising street table when I was passing through Taree in 1997. It is my intention to attempt the growing of another favourite being blue Forget Me Nots from seed when I can get into the garden. Once upon a time in the 1970s and 1980s I had Borage in my very large garden, I used to encourage it to grow by self sowing. The flowers were a favourite sweetie. Dichorisandra is a beautiful plant and I like the fact that it grows in shade. Borage and forget-me-notsare lovelyif enthusiastic self-seeders. Deirdre

9/9  Gillian - 2119 (Zone:10 - Warm Temperate) Tuesday, 26 November 2019

What a great article on blue flowers, they really light up the garden. As well as those you mentioned I also have my Dichroa versicolour flowering at the moment. I acquired a couple of new plants which have just started blooming and thanks for the name "Salvia sinaloensis"- I have always admired this plant in other people"s gardens so I am happy to have it in my garden now. I look forward to it forming a thick ground covering clump. Also love the Browallia americana. Thanks Deirdre. I love Dichroa -- mine is not yet out so I forgot to include it in the blog. It is an amazing plant, flowering for so long. I like growing it near hydrangeas as it blends in but provides interest by its differences to the hydrangea blooms. Deirdre

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