Deep purple

Sunday, 11 April 2010

Salvia leucantha in the garden of Alida Gray in Sydney

Whilst 40 years ago these words conjured up visions of smoke-filled rooms and extremely loud hard rock music, nowadays, in middle age, they make me think of the colour of some of my favourite flowers which are blooming at the moment!

Purple, defined by colourists as 'red-violet', has been historically associated with royalty and power. In ancient Rome, Egypt and Persia, purple was used for imperial robes and the earliest dye, 'Tyrian purple', was extracted from tiny marine molluscs, making it rare and expensive. Perhaps this is what gives it its rich and regal air, but whatever the reason, it brings a strong note into the autumn garden.

Tibouchina Alstonville

The most prominent purple at the moment comes from the domed Tibouchina lepidota (ht 3m) that have burst into bloom over the past few weeks. The most common of these is the cultivar 'Alstonville', which can be grown as a shrub by keeping it pruned, or shaped into a small tree. It is a wonderful sight when backlit by the autumn sun. The flowers look pretty with the pale pinks of Camellia sasanqua but one of my favourite colour combinations is purple with orange or gold, and the Tibouchina looks stunning when paired with orange Canna or Dahlia, or the bird-like blooms of Strelitzia, which are having a renewed flush at the moment.

A mystery Salvia, similar to Black Knight

Salvia also offer some vibrant purple flowers at this time of year. 'Purple Majesty' blooms all through summer and autumn; 'Black Knight' is a similar cultivar, but has darker calyces. I have an interesting specimen (pictured left), which is similar but perhaps not identical to 'Black Knight', and is in full bloom at the moment. Unlike 'Black Knight', this one self-seeds. I grow it with silver foliage, such as Plectranthus argentatus and Artemisia 'Powys Castle', and the dark foliage of purple fountain grass (Pennisetum setaceum 'Rubrum'). The purple form of Salvia leucantha (shown at the start of the blog) has long-flowering and attractive spikes of plush blooms. The lovely lime-calyx cultivar of Salvia mexicana, with its blue-purple flowers shows another effective colour combination for purple: I love the contrast of the colour lime with purple as seen in the flower spikes of this autumn-flowering Salvia. Lime green is purple's opposite, or complimentary, hue on the colour wheel and this seems to work as a colour pairing in the garden.

The many species and cultivars of Plectranthus have been decorating the shady parts of our gardens over the last month or so; the purple Plectranthus ecklonii, which provided a stunning mass of feathery blooms, is just about over, but one of my favourite groundcover Plectranthus - the cultivar 'Nicoletta' - is just coming into flower. It has dainty purple spikes, above its wonderful velvet silver foliage; it is a most useful plant, which will grow in either sun or shade.

Dichorisandra thyrsiflora

A slightly different hue of purple is provided by the so-called blue ginger flower (Dichorisandra thyrsiflora, ht 2m) from Brazil, which is blooming now in the shade. The beautiful clustered flower heads are purple-blue and appear atop of ginger-like stems of leaves. It belongs to the Commelinaceae family of plants, which includes the various Tradescantia species. Tradescantia pallida 'Purpurea' (syn. Setcreasea purpurea, Tradescantia pallida 'Purple Heart') is a wonderful foliage plant with rich purple leaves that can provide colour all year round in shade or sun, and can provide a good companion to its cousin the blue ginger.

Also in shady spots, the pretty trumpet flowers of cape primrose - Streptocarpus hybrids - often come in hues of purple, and these are in bloom at the moment. Often thought of as pot plants, the more robust specimens of this plant will grow in the garden and form clumps.

Heliotropium arborescens Lord Roberts

Heliotropium arborescens (ht 75cm) - sometimes called cherry pie because of its deliciously perfumed purple flowers - can bloom all year round in our benign Sydney climate, and it is a good little shrub to include in a sunny border. The cultivar 'Lord Roberts' is recommended for its richly coloured flower heads. Trim off spent flower-heads to promote continued bloom.

To provide purple flowers through winter and spring, now is the time to plant up some bowls of purple annual Viola or pansies, which will brighten up the days ahead!