The delicate flowers of Viola cornuta are as different as possible from those large-faced, colourful pansies you see smiling at you in trays.
For one thing, Viola cornuta lives for many years and flowers in flushes between April and September. At first the wispy, white, soft-blue, rose-pink or mauve flowers hug the ground above bright-green crinkly foliage.
Then the stems get leggier and stretch up through roses and hardy geraniums to great effect. The trick with them all is to crop them twice a year, straight after the first flush of flower and then again in mid-September. The second chop allows them to form a bushy cushion of foliage that keeps out wintry weather.
There are many other long-lived, small-flowered violas with great charm and they include a whole series named after ladies. Look out for the fragrant lilac and yellow ‘Etain’, the dark-blue and white ‘Rebecca’ and the stripy blue and white ‘Columbine’.
Where to plant
Viola cornuta is an easy and accommodating plant to grow in herbaceous or woodland borders, and it’s particularly useful under roses planted with softly-hued herbaceous plants like hardy geraniums, campanulas and peonies.
This viola, introduced in 1776 from Spain and The Pyrenees, prefers moisture-retentive soil and good light rather than fierce sun. It will also do well in shade, as long as the soil is not too dry.
The one situation Viola cornuta hates is dry soil.
When to plant
Planting Viola cornuta in spring or early summer is best. You can also plant in September too, although it is harder to find well-grown plants then. Beth Chatto is a good autumn supplier.
How to plant
Choose compact tidy plants with lots of fresh growth. Make sure that the soil is fertile and well dug, then water them in well.
Viola cornuta makes an excellent edging next to paths and paving: it will soften hard edges without becoming too sprawling.
When to cut back
Every time your plants look ragged cut them back hard and they will re-shoot and bloom again. And don’t forget the September trim: this will enable them to live for many years. Straggly plants often die off. This is good advice for all violas.
How to propagate
Violas grow easily from cuttings taken from the new growth springing from the base. These are best taken from the re-growth that follows after the viola has been cut down following the first flush of flower, typically in late June or July.
Coarse horticultural sharp sand, or a mixture of 50% seed-sowing compost and grit, work well. Fill small seed trays or pots with the mixture and, taking the lower leaves off the bottom of the shoots, plunge the soft-stemmed cuttings into the medium, submerging two thirds of the cutting if possible. The ideal length of cutting material should be two to three inches.
Water them well once and then keep them only just moist. These cuttings root quickly without heat and, once they are showing signs of root, carefully lift them and pot them up. The usual method for testing for roots is to give them a gentle tug. Rooted cuttings stay put.
Viola cornuta is commonly known as the 'horned violet' because it has a long spur full of nectar at the back, so bees adore them.
The white-flowered form, ‘Alba’, is very effective in shade planted with ferns, pulmonarias and spring-flowering bulbs and woodlanders. It can also be used with white tulips (like the green and white Viridiflora ‘Spring Green’) and lily of the valley (Convallaria majalis), Solomon’s Seal (Polygonatum x hybridum) and similar spring-flowering woodlanders. It will also creep among hostas.
The others (pastel-tinted blues, mauves and rose-pinks) mix well with summer herbaceous. They can be used with taller hardy geraniums, Campanula lactiflora ‘Prichard’s Variety’ and ‘Loddon Anna’, heucheras and London Pride (Saxifraga x urbium).
Viola cornuta is an indispensable plant under roses and its cushion-forming habit will help to prevent the spread of Black Spot. The plants help prevent the spores from reaching the ground.
Varieties of Viola cornuta
Some varieties are easier to keep in the garden than others. This may be a question of hardiness, or vigour. Some have fuller, rounded flowers and others are much more delicate and violet-like. There are other good forms just labelled 'Lilacena' (lilac) or ‘Purpurea’ (purple).
The true Viola cornuta has pale-blue wispy flowers, but there is a purple-flowered form in commerce with fuller, more-rounded flowers.
Viola cornuta ‘Alba’
Indispensable with clear, classic white wispy flowers. Should seeds appear (and they do if you forget to cut them back), seedlings do come true and produce more whites. A ‘must grow’ but more effective in dappled light!
Easy and vigorous with feminine, clear rose-pink wispy flowers. Only faintly veined.
Cream flowers that fade to blue-white with flowers that hover halfway between pansy and violet.
Pale-pink flowers with a dark eye and veins.
One of the best, with sky-blue flowers and a yellow eye.
Where to buy
Wildgoose Nursery - www.boutsviolas.co.uk