Pansies (ht 20-30 cm) are derived from cross-breeding of several Viola species, including V. tricolor and V. cornuta, and they have larger flowers than any of their parents - up to 10 cm across in some cultivars. Leaves are heart shaped and lush. The flowers can be all one colour; bicoloured; or with central markings that look almost like little faces. The colour range of the flowers is very wide and includes almost every hue of the rainbow - and even black! They can be grown from seed planted in late summer or early autumn, or purchased in punnets in autumn. They like a sunny position (but will also grow in part or dappled shade) with good, humus-rich soil and do better if given plenty of water and regular liquid fertiliser. I also think they like a bit of lime added to the soil if it tends to be on the acidic side. They are well suited to being grown in pots. The best time to plant them out seems to be autumn, to give them time to establish their root systems whilst the weather is mild. They will begin flowering in late winter and blooming will continue throughout spring. Pinching off the spent flower heads will keep them in bloom for an extended period. They may keep flowering into early summer if grown with protection from the afternoon sun. Snails and slugs can be a problem.
In recent years, groundcover-like cultivars such as 'Spreading Violet Wing' have been released, which form a 60 cm wide carpet or which can be used to cascade over retaining walls or in baskets.