Pansy breeding has produced a wide range of flower colors including yellow, gold, orange, purple, violet, red, white, and even black (very dark purple) many with large showy face markings. A large number of bicoloured flowers have also been produced. They are generally very cold hardy plants surviving freezing even during their blooming period. Plants grow well in sunny or partially sunny positions in well draining soils. Pansies are developed from viola species that are normally biennials with a two-year life cycle. The first year plant produce greenery and then bear flowers and seeds their second year of growth and afterwards die like annuals. Because of selective human breeding, most garden pansies bloom the first year, some in as little as nine weeks after sowing.
Most biennials, including pansies, are purchased as packs of young plants from garden centres and planted directly into the garden soil. Under favourable conditions, pansies can often be grown as short lived perennial plants, but are generally treated as annuals or biennial plants because after a few years of growth, the stems become long and scraggly. Plants grow up to nine inches (23 cm) tall, and the flowers are two to three inches (about 6 cm) in diameter, though there are some smaller and larger flowering cultivars available also.
Pansies are winter hardy in zones 4-8. They can survive light freezes and short periods of snow cover, in areas with prolonged snow cover they survive best with a covering of a dry winter mulch. In warmer climates, zones 9-11, pansies can bloom over the winter, and are often planted in the fall. In these climates, pansies have been known to reseed themselves and come back the next year. Pansies are not very heat-tolerant; they are best used as a cool season planting, warm temperatures inhibit blooming and hot muggy air causes rot and death. In colder zones, pansies may not persist without snow cover or protection (mulch) from extreme cold or periods of freezing and thawing.
Pansies, for best growth, are watered thoroughly about once a week, depending on climate and rainfall. To maximize blooming, plant foods are used about every other week, depending on the type of food used. Regular deadheading can extend the blooming period.
Source : http://en.wikipedia.org/wiki/Pansy
See Also : Florist, Florists, Flower