"Purple patch"

My garden has lots of purple flowers at the moment.
Sunday, 26 October 2014     

The climber Petrea volubilis is in bloom now

I was simply enjoying my good fortune of having lots of purple flowers in my late spring garden, but when I stopped to think about it, I realised the word 'purple' covers a wide spectrum of hues! The colour termed 'purple' is a secondary colour (and strictly speaking it is 'violet') that falls between the primary colours of red and blue on the colour wheel, but we also tend to call 'purple' the tertiary colours formed as it transitions towards red on one side and blue on the other side. The tints and shades form by adding white or black to these three hues (and all the gradations between them) mean that there is a multitude of purple possibilities.

I find it quite hard to know exactly what the colour pure violet actually is, but maybe a flower out at the moment that comes closest to it is Salvia 'Purple Majesty', which has just started its long period of bloom. Being the darkest of the saturated colours, violet flowers benefit from lighter, brighter neighbours, such as silvery Plectranthus argentatus, or paler unsaturated tints of itself, such as lilac and lavender. In my garden at the moment, these pretty pastels are found in the delightful climber Petrea volubilis (pictured at the start of the blog) growing on a pergola, with trusses of simple violet flowers held within cross-shaped lilac calyces, which persist long after the flowers have fallen. This is the first year mine has bloomed properly, and it is providing much enjoyment.

Other flowers of a similar hue out now are Tulbaghia violaceae and a pretty bearded Iris (pictured at left). The Tulbaghia will continue to flower until late autumn. The irises, on the other hand, don't bloom for very long in Sydney, but they do provide some gorgeous colours for creating pictures in the garden. Though I prefer plants that bloom over many months, it is also nice to have some flowers that come and go, providing highlights that can be appreciated all the more because they are transient.

Saturated blue-violet (sometimes called 'indigo' by colour theorists) is an elusive hue in my garden; maybe Salvia 'Indigo Spires' comes closest to it, and I do have some pastel-coloured flowers that seem to be tints of this hue. A perennial form of Ageratum houstonianum is just beginning its long blooming season, with its strange fluffy inflorescences. This plant has been the subject of a lot of tip-pruning over the last few months and the result has been a nicely shaped, compact specimen. Campanula flowers often seem to fall in between blue and violet, and the spires of Campanula rapunculus are providing lots of colour now. I enjoy these pastel colours next to strong, bright pink hues, such as those provided by Salvia 'Joan' and a vigorous Dianthus, as well as with clear blues.

The addition of red pigment tips violet towards the hues known as purple and magenta: warmer than the straight violet or blue-violets. My new favourite Salvia - a cousin to 'Wendy's Wish' and 'Ember's Wish' called 'Love and Wishes' - has flowers of this colour, held in sultry dark calyces, and it has not stopped blooming since I planted it in April. The flowers are very similar to those of Salvia 'Desley' but its form is much more compact, and it grows to around 80 cm. It seems just as good a plant as 'Wendy's Wish' and 'Ember's Wish'.

Adding white to red-violet gives mauve, and I have a few examples of this colour at the moment. One is the climber, Clytostoma callistegioides, sometimes known as the violet trumpet vine, which has trumpet-shaped mauve flowers and is quite spectacular when fully out - and grows well in our climate. Darker shades of red-violet are quite thrillingly dramatic, and I have self-sown Aquilegia hybrids in this colour, along with the flowers of Geranium phaeum 'Samobor'.

I think that flowers of all the variants of what we might call purple - violet, blue-violet and red-violet, in their saturated and unsaturated forms - look fabulous growing together, as well as with cool pinks and blues, and with silver and/or dark purplish foliage. I have found that the purchase of an inexpensive colour wheel from an art supply shop has been a great help in understanding the hues of flowers in my garden - and how they can best be combined!

 Reader Comments

1/9  Janna - UK Monday, 27 October 2014

I learnt all of this the hard way when I created a "purple and white" border in my previous garden! Some of my purples looked terrible when combined with others for an overall effect. I, too, find a colour wheel very useful and actually wrote a blog on this topic last month. Lovely to read about others thinking about it in a similar way. Thanks, Janna. I think when purples are used together with no other colours mixed in, the different hues would not necessarily go well together. I do mix the various hues in my borders but there are many pinks, blues, silvers and white in between. Deirdre

2/9  Helen - 7256 (Zone:10 - Mediteranean) Monday, 27 October 2014

Ive been watching the purples, blues and pinks in the community of self sown aquilegias in my garden interplay with an old lilac tree and gold and white spuria iris. The coulmbine are mostly dark red purple but some are dark blue or even dark brown - so that the occasional mid lavender ,pale lavender, deep pink, pale pink and white are a relief. These combinations are inherited with the garden. Ive added white federation daisies, yellow geum and cineraria in a shady corner. Your aquilegias sound a delight. The dark colours do need paler colours I think as a contrast. Deirdre

3/9  Alison - 2125 (Zone:10 - Warm Temperate) Monday, 27 October 2014

I have seen a stunning petrea volubilis or purple wreath vine out in flower draped over black wrought iron patio fencing at my friend"s house in West Pennant Hills. Its a great colour combination! That sounds amazing! Deirdre

4/9  Trudi - 4223 (Zone:10 - Warm Temperate) Monday, 27 October 2014

I love your blue and purple plants. I grow some blue and purple Salvias in my newly established butterfly garden. Salvias are wonderful providers of blue and purple colours! How nice to have a butterfly garden. Deirdre

5/9  Carole - 2230 (Zone:10 - Warm Temperate) Monday, 27 October 2014

I saw a petrea volubilis in flower for the first time about 2 weeks ago at a nursery north of Yeppoon in Qld. The reality confirmed my opinion of it"s beauty after seeing photos in the past. Now I am struggling with a desire to acquire one, which is not a practical idea when we have just this year taken up the practice of cool season retirement travelling with a caravan. We arrived home from our journey yesterday, me with a mid-mauve Crucifix orchid plus colour surprises still to discover:-) The Petrea is certainly lovely; your crucifix orchid sounds very pretty too! Deirdre

6/9  Margaret - 2122 (Zone:10 - Warm Temperate) Tuesday, 28 October 2014

I find it hard to define purple/violet - there are so many hues - but the colour is so welcome in the garden, mixing as it does with blues, pinks, lemon and especially lime. My petrea is yet to flower, but it looks pretty alongside a white mandevilla, over a nearby arch. Yes you are so right - purples and violets are stunning with lime and lemon, as well as blues and pinks. Deirdre

7/9  Serena - 2483 (Zone:11A - Sub-tropical) Tuesday, 28 October 2014

I was amazed to see that "Ageratum houstonianum" is being grown as a garden plant! Here on my acreage in Northern NSW I am trying to eradicate it constantly! It is everywhere, smothering pasture, along with cuphea....both of which are garden escapees! In learning to identify all the weed varieties here, they have nearly all been introduced to this country either deliberately or inadvertently. The worst enemy is camphor laurel. Also lantana, crofton weed and white & corky passionfruit. Yes so many garden plants have the potential to be weeds if they get into the bush or pastures, especially in warmer areas. This particular tall Ageratum that I grow is a perennial form, which has never self-seeded in my garden. However, I have seen the smaller annual form self-seed in other gardens and I do not grow that one. Deirdre

8/9  Chris - 4034 (Zone:11A - Sub-tropical) Wednesday, 29 October 2014

These colours are my favourite and i try to think of combining colours according to the colour wheel. Nature does not place flower colours in an order, so i use this as my excuse when things don,t match. Since i have been watching your blog, and have purchased a new plant, I stop and think of size and colour first. My next purchase will be an ageratum. Thanks for your inspiration. Thanks, Chris. As noted above, I have not ever had a problem with the perennial form self-seeding but keep an eye on it if you grow it as in warmer climates it might do that. Deirdre

9/9  Bronwyn - 2089 (Zone:10 - Warm Temperate) Monday, 03 November 2014

Hello, Is the vine called Petrea Volubis also known as Sandpiper Vine? Thank you Bronwyn. Yes it is sometimes called sandpaper vine instead of purple wreath vine because the leaves feel like sandpaper, I think! Deirdre

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