Pansies and Violas in Japan: The Winter Flower That Carried a Butterfly North
In Japan, late October is when garden centres fill up with trays of pansies and violas. For many gardeners here they are the flowers of winter, the colour that carries a bed from autumn frost to spring.
We are a small tree care and landscape business in Mie Prefecture, central Japan. Pansies are not our main work, but we meet them in almost every garden we visit in the cold months. This page explains why they are planted when they are, how Japanese breeders changed them, and the butterfly that followed them across the country.
When to plant
The usual advice in Japan is to plant when the air temperature drops below about 20°C. In our part of central Japan that means late October to November.
Planting earlier is possible, but in warm weather the stems stretch and the plant grows loose and floppy. Plants set out in cool weather stay compact and flower more evenly through the winter.
Pansy or viola?
Garden pansies were bred in Europe from the wild heartsease, Viola tricolor. In Japan, flowers about 4 to 10 cm across were long called pansies, and smaller ones of 2 to 4 cm were called violas. Today there are so many crosses that size alone no longer tells them apart.
One old Japanese name for the pansy is jinmensō, "the human-face flower". Look at a pansy with dark blotches and you can see why.
A spring flower that learned to bloom in winter
Wild violets and the early garden pansies were mainly spring flowers. Modern strains that keep flowering through short, cold days are the result of long breeding. When we see a winter bed in full colour, we are looking at something people shaped over many years.
Japan has become one of the most interesting places in the world for this work. Small specialist breeders have created pansies and violas with ruffled petals, antique colours and shapes that do not look like pansies at all. Sato Nursery (Satō Engei) in Gunma Prefecture, run by the breeder Isao Sato, is known for varieties such as Nouvelle Vague, Dracula and Robe de Antoinette. On release days, people queue outside garden centres for them.
The butterfly that followed the pansies
If you grow pansies in Japan, sooner or later you will find a black caterpillar with an orange stripe and soft spines, eating the leaves. It is the larva of the Indian fritillary, Argyreus hyperbius, called tsumaguro-hyōmon in Japanese.
This butterfly once lived mainly in warm western Japan. Its larvae feed on plants of the violet family, wild violets and garden pansies alike. It reached the Kinki region around 1986, the Kanto region around Tokyo around 1993, and the Tohoku region in the north around 2002.
Two reasons are usually given for this fast spread. One is milder winters. The other is the pansy itself: a food plant now growing in flower beds in almost every town. The flowers we plant for our own pleasure became a road the butterfly travelled along.
The female has another story of her own. Her black-tipped wings resemble those of a distasteful butterfly, the plain tiger, which birds learn to avoid. She borrows its warning.
The larva looks dangerous, but the spines are not venomous. They can prick, so it is best not to handle it with bare hands. Many Japanese gardeners now leave a few plants for the caterpillars and enjoy the butterflies that follow.
Keeping them flowering all winter
Pick off faded flowers at the base of the flower stalk. Pansies flower one after another, and the more often you remove spent flowers, the less the plant tires and the longer it blooms.
In winter, water on a sunny morning. In cold weather the soil stays wet for a long time, and soil that never dries invites grey mould.
When the stems stretch and the plant opens up in spring, cut it back by about half. It will close up again and flower once more.
The basics
Pansy and viola: Viola, violet family (Violaceae). Origin: Europe. Grown as an annual, 10 to 30 cm tall. Very hardy to cold, weak in summer heat. A long flowering season and easy for beginners.
What we see in our work
A garden does not stop at its fence. A tray of winter flowers bought in October fed a butterfly that spread hundreds of kilometres north in less than twenty years. When we look at a flower bed, we try to remember that it is also a meal, a shelter and a map for something else.
