Dead-nettle or Urtica mortua (the name by which it was often known in mediaeval Latin) is a hardy plant. The temperature only has to rise slightly above freezing and it comes to life. It is one of the overwintering weeds of field and fallow land, though it also grows in large numbers in gardens, waste places, and along field paths.

It is exceptionally resistant to low temperatures so that on warm winter days it is not unusual to find it flowering even in a furrow partly covered with snow. In thick stands, where it is crowded by other growths such as field crops, the Field Pansy is erect with few branching stems; populations growing after the harvest, when the competition is less, are richly branched and form large clumps.

In drier situations or at higher altitudes it is an annual, but in lowland country with mild winters it easily survives the cold season and is one of the first plants to bloom in early spring. The flowers appear as early as March and, quickly attracting the attentions of the honey-bee, are borne in succession until October. Flowering continues even in very cold weather although they do not always open fully (in which case the plant is self-pollinating).

Distinguishing these two pansies from each other is very difficult. The Wild Pansy usually has large petals, often twice as long as the sepals; those of the Field Pansy are smaller, at most the same length as the sepals. The Wild Pansy is tri-coloured as its Latin name indicates: the upper petals are violet, the others yellow and white. The spur in long, longer than the calyx appendages, while in the Field Pansy it is the same length as the appendages. Although the Field Pansy is usually yellow, sometimes the upper petal shows a trace of violet.

Both pansies are native to Europe and nowadays are companions of field crops almost throughout the world; they are even found at mountain elevations wherever there is arable land.

The flowering period is from April to October. Shortly after the flowers have faded they are followed by splitting capsules containing tiny seeds.