Combining different colours creates particular moods and feelings. The association of blue with the cold is so inbred in our perceptions, thanks to short winter days and the low angle of the sun which wrings out the red and orange light at that end of the spectrum.

So limiting your flower and foliage colour palette to tints of blue, lavender, white and chrome yellow will recreate this cool look and 'feel', even in summer. Green, featuring blue in its spectral range, also has a freshening effect on colour schemes.

Cool hues also engender a sense of calmness and peace. A garden planted in this way will help you relax and escape the heat of the day. And these colours seem to work best in the parts of the garden that are in shade for at least part of the day, where the fresh tints and tones can be seen at their best.

Rosy says

Pale tints of blue (those created by the addition of white) tend to create the coolest, freshest effects. Mix in darker shades to make them appear cooler.
Be careful with yellows. Green-yellow will sit well in a cool planting scheme, but orange-yellow will immediately turn up the temperature!
You can consider half of the colour wheel to be cool, ranging from blue, through green to yellow.

"You can consider half of the colour wheel to be cool, ranging from blue, through green to yellow."

Colour Wheel Taken from Rosy Hardy's Book - 25 Years of Chelsea

Below are a few of the cool colour planting combinations Rosy has used within her RHS Chelsea displays, these would work in the month of May. You can of course use a mixture of plants with a similar cool colour palette to create planting schemes to give you flower from March until September...

Planting combinations for a sunny site

Iris 'Jane Phillips' (TB) seen here with the soft yellow flowers of Thermopsis lanceolata -

Another one of Rosy's tips "Pale blue, yellow and white are given extra stand out by contrasting them with purple and pink." the little touches of pink in this picture are provided by the flowers of Rehmannia 'Walberton's Magic Dragon' PBR (Rehmannia is slightly tender - we hope to have stock available a little later in the year)

Above - The cobalt-blue flowers of Anchusa 'Loddon Royalist' are seen mingling with the zesty yellow flowers of Achillea 'Moonshine' , lilac-mauve Geranium pyrenaicum 'Isparta ' and at the front of this planting scheme Salvia nemorosa 'Sensation Rose' or you could add Salvia nemorosa Caradonna Pink Inspiration ('Tuitsalv') help to create a colourful, yet relaxing planting scheme. To add height and light to this otherwise sun loving planting combination, Rosy planted white foxgloves, Digitalis purpurea f. albiflora beneath the trees - don't forget that even the smallest amount of shade can be used to extend the range of plants you can grow in a
sunny garden.

Below - We can see how the white flowers of Orlaya grandiflora can be used to pick out the white colour at the centre of the cobalt-blue Anchusa 'Loddon Royalist' flowers .

Planting combinations for a shady site

Above - Swathes of green, blue and white create a fresh cool look ,even with the addition of pale pink. Here we see the white flowers of the shade loving Silene fimbriata . At the base of the Silene we see the blue flowers of the summer deciduous Corydalis flexuosa 'China Blue' . Ferns & Hostas , Rheum palmatum with its huge rhubarb-like leaves and Angelica archangelica add structure.

Below two top plants for deep shade - Geranium phaeum 'Album' bares clear white flowers which show up well in a shady spot. And the flowers of one of Rosy's favourite British native plants, Silene fimbriata .

You will find more medal-winning planting combinations in Rosy Hardy's Book - 25 Years of Chelsea .

Plus 80 beautiful plants for problem places