Many people like to plan their flower gardens along colour lines.
For a while, it was almost compulsory to plant everything in white, following English trends, but fortunately that fad has passed, and the trend is once again for more colourful gardens.
The Head Gardener has a passion for blue, and many of her favourite plants have blue flowers. The term ‘blue’ covers a multitude of different shades in the gardening world, as many plants that do not have naturally blue flowers have been bred to have shades that approximate blue, to a lesser or greater degree.
For example, consider the blue rose. Despite the many photoshopped “varieties” available online, there are no blue roses. The closest varieties, such as the old favourite ‘Blue Moon’, are lavender coloured, and although they are attractive plants [in my mind anyway] they are not blue.
Similarly, the blue rhododendrons I have seen have all been mauve rather than blue. Some like ‘Blue Diamond’ are very attractive plants, but blue they are not.
One of the Head Gardeners favourite plants is the fern-leaved corydalis, perfect for a slightly shady position in the front of her equally ferny leaved thalictrums. There are several different forms of these, ranging from deeper blue right through to sky blue. I like ‘Porcelain Blue’ which is lighter in colour, but ‘Blue Heron’ is also very appealing, as is ‘Frere David’, named after a famous priest/ plant explorer. All of these are spring flowering, and likely to take a break over summer, but they will come back with another great display in the spring.
There are a great many blue irises, among both the bearded and beardless types. Many of these have purple intrusions into their shades, but the best of both types approach pure blue. I have been breeding blue Pacific Coast irises for a few years now, and most years have a new one that deviates away from the usual, many of them having a prominent turquoise flash.
In the first blue garden that she ever planted, the Head Gardener planted a cousin to the irises, a South African treasure called Aristea ecklonii. It was quite new to the country, and perennial nurseries were pushing it quite hard, extolling its small flax-like growth habits, and its small bright sky-blue flowers held on 30 cm high spikes. It grew well in her garden, and people certainly commented on how blue the flowers were. Other people were commenting too – it was growing too well, as it escaped the garden and went feral in the environment. It is now illegal to sell, distribute, breed or release this plant. Ouch!
Of course, the blues of all blue flowers are the gentians. Over the years, we have tried several different cultivars but have never succeeded getting them to establish properly in our gardens. When I go to Dunedin and see them growing wild in the rock garden on the banks of the Leith, I am insanely jealous.
This time of the year, one of the prettiest of the blue-coloured shrubs is at its best – plumbago. This is a beautifully pastel-blue coloured climbing, or perhaps just sprawling, softly wooded shrub that can be trained as a climber or left to clamber around other plants. The flowers are softest blue, with a hint of grey, which the name plumbago [Latin for lead] suggests. The most found variety is ‘Royal Cape’ which is slightly deeper coloured – it is a great plant. The Head Gardener has a plant of this which leans out across the edge of the lawn, and I have to lift it up each time I mow – the flowers are at the end of the branches and if I left it there, I would take all the flowers off. It is worth the hassle!
One of my friends calls this time of the year the “Salvia Time” in her garden, as so many different salvia species and cultivars come into their best at this time of the year. Probably the bluest is the bog sage, S. uglinosa. This is a very hardy and energetic plant, with spikes of beautiful sky-blue flowers on very upright stems. It is quite vigorous, and is tall growing, so it needs placing with care. A smaller cultivar called ‘Ballon Azul’ is probably better for smaller gardens.
My mother grew this species. I have a different one in my back border – ‘Black and Blue’, a form of S. guaranitica, which flowers later in the season with bright sky-blue flowers that come out of deep purple [nearly black] calyces. It is very hardy, the leaves having a nice anise scent if crushed. Mine grows to just over a metre, and is one of my favourite long-lived perennials.
