The colour we use in our gardens, be that foliage or flowers, is highly personal but is also key to creating the mood of the garden. We see soft pinks and whites as romantic, reds and yellows as vibrant, and blues and purples as relaxing.
Colours can also evoke a sense of place, or more particularly of climate. We tend to associate soft, romantic colour schemes with temperate cottage gardens and vivid reds with the tropics. There is some reasoning behind this.
In hot climates the intensity of the sun tends to wash colour out and make pastel colours look somewhat dull. In these climates the more vivid the colour, the more likely it is to be noticed by pollinators in the strong light. This of course relates to visual pollinators like birds who particularly like red flowers, but bees and other insects are also visual pollinators. Just because we have these simple associations does not mean we cannot experiment a little further with colour in the garden.
For those of you who follow my writings here, you will have noticed that I find all colours somewhat irresistible in my own garden and I lean towards a full-scale colour riot. However, I have designed and created many gardens for others where I have had the delight of playing with colour schemes. After all, when working for someone else the goal is to create their dream garden – I already have my own.
I have also written here previously about the need for shade. Shade in a hot climate is not only valuable for keeping things cool, it provides the gentler dappled light that brings a soft romantic colour scheme into its own. In the harsh sunlight of a hot climate, shade is imperative for the success of a garden full of pastel coloured flowers.
With or without shade we can create a sense of warmth or coolness in a garden using colour. Hot colours in a cool climate will add a sense of warmth. Cool colours in a hot climate will create a cool feeling garden. Green is usually the go-to colour for a cool garden and it does the job exceptionally well. Lush greens certainly do give a sense of coolness, especially dark rich greens. We can also use flowers very effectively to create a sense of cool in a garden, in particular by focusing on a blue theme.
This colour scheme is not as commonly used in hot climates as you might expect, but it can be very rewarding. A garden with an abundance of blue and purple flowers is usually cooling to look at on a hot day.
I created a small cottage garden a few years ago using predominately deep blues and purples, highlighted with white. It surprised me just how cool it was to be in, even when I was in the full sun. The main cooling feature was the green lawn and hedge which cut reflected light, but the greens and blues in the garden tricked the brain into thinking the space was cooler than it was – and therein lies the power of colour.
We do not automatically think of blue and purple flowers in hot climates, and yet there is a wealth of choice available to us in this colour range. I have put together a small list of some I enjoy here in Brisbane. Have a go at creating a cool-looking cottage garden to enjoy through a hot summer using a theme of blues and purples. If this feels a little too cool for you, you can add a hit of excitement with oranges or yellows as accent plants, or some whites for brightness.
Be aware that if you choose only very light blues in full sun they may look washed out, and very dark shades can tend to disappear in heavy shade. Play around with the various tones of blue and purple to find a combination you enjoy.
Plants for plenty of sun:
Plumbago (Plumbago auriculata) This old-fashioned shrub is still a hardy favourite. New varieties flower in a deeper blue and sucker less.
Salvias (Salvia spp.) Examples include Cost Rica Blue, Black and Blue, African Skies – there are an almost infinite amount of blue varieties to choose from.
Blue cone flower (Pycnostachys urticifolia) Flowering right now in a vibrant blue, the unusual shaped flowers are sure to be noticed in the garden.
Blue monkey tails (Stachytarpheta spp.) This one flowers almost all year and self-seeds readily. It is a great “filler” for a blue themed cottage garden.
Lousiana iris Although they have a relatively short flowering season, the spectacular flowers are worth the wait. They come in a huge range of colours, including a lovely rich purple and both dark- and light-blue. This iris likes to grow in shallow water, but will do well in the garden with plenty of water.
Convolvulus (Convolvulus mauritanicus) A very hardy ground cover with greyish leaves and bright-blue flowers for much of the year.
Heliotrope (Heliotropium arborescens) This one is more purple than blue but is available in a variety of shades, including one with lime coloured leaves for extra excitement. The perfume is delicious, hence the common name, Cherry Pie Plant.
Dog bane (Plectranthus ornatus) The greyish leaves of this one make it very drought hardy but it also copes well in our humidity. It will take a lot of shade but needs sun to flower. Another excellent plectranthus for us here is Plectranthus barbatus which is quite tall, has velvety green leaves and large deep-blue to purple flower spikes and, even better, is happy to grow and flower in shade.
Skullcap (Scutellaria spp.) There are a few scutellaria species with blue flowers worth growing here in the subtropics, but also others with flowers which are vibrant pinks, reds and yellows.
Coastal rosemary (Westringia fruticosa) There are a number of different cultivars available, including some with delightful pale-purple flowers and some which are almost ice-blue.
Brazilian snapdragon (Otacanthus caeruleus) Here is a tip – ‘caeruleus’ means dark-blue in Latin, so plants with ‘caeruleus’ in the name probably feature blue flowers or berries.
Hovea (Hovea spp.) This is a genus of purple pea shrubby plants native to Australia. They can often be found in native plant nurseries. While it is more purple than blue, it does make an attractive native plant to give a cool burst of colour in a cottage garden.
Blue butterfly bush (Clerodendrum ugandense) The common name refers to the shape of the flowers which have lovely curly stamens which resemble butterfly antennae. Not the most eye catching shrub in the distance but the blue flowers with curly stamens are good value if close enough to appreciate.
Plants that prefer some shade:
Giant sage (Brillantaisia subulugurica) This large shrub has the potential to be weedy so take care in disposing of cuttings, but the giant purple flower spikes are well worth the effort.
Blue ginger (Dichorisandra thyrsiflora) An old-fashioned favourite in subtropical gardens. The vibrant purple flowers light up many a shady nook in an old Queensland garden.
Blue sage (Eranthemum nervosa) Like the giant sage, this one is not a sage at all. It also has a fairly short flowering season, flowering in early spring, but the flowers are a light- to mid-blue and almost glow in shady gardens. The plant will grow in full sun but tends to be less lush, and the flowers are paler in the sun.
King’s mantle (Thunbergia erecta) Another rich deep-purple, a colour I am very attracted too. While these darker colours can almost disappear in deep shade, in dappled light they are rich and vibrant.
Salvia ‘Black Knight’ This large salvia has rich deep-purple flowers all year round in shady parts of the garden.
Walking iris (Neomarica gracilis) This one is a white flower with a purple centre. The flowers only last one day but for a short time in September they put on a great show and really brighten areas under trees. There is also a larger version with purple flowers (Neomarica caerulea) which is less commonly available but well worth seeking out.
Flax lily (Dianella caerulea) This native grass-like plant is very hardy and will take a lot of sun and shade. It has large spikes of small blue flowers followed by purple berries, both of which are highly attractive. Bees love the flowers. There are many different cultivars available now and it is becoming more common in landscaping.
Nodding violet (Streptocarpus caulescens) Grow it in a hanging basket for the best effect, and don’t over water.
Blue butterfly pea (Clitoria ternatea) The flowers on this are the most glorious blue and are used in Asia as a natural food colouring.
Heavenly blue (Ipomea tricolour) This is related to the dreaded Morning Glory vine but so far has not become a weed – let’s try and keep it that way. There are many cultivars in a variety of shades of blue and purple.
False sarsaparilla (Hardenbergia violacea) This native is extremely pretty and comes in both purple and white varieties. Often it works better as a scrambler than a vine.