Pansies (Viola x wittrockiana) and their relatives, violets and violas, are part of a large plant family that includes annuals, perennials and even small shrubs. All have beautiful flowers, but pansies have some of the largest and most colorful. Gardeners have long had a special fondness for the bi-colored types with “faces”--dark blotches on lighter petals. Though pansies are often raised as annuals, they are winter hardy under certain conditions.
Colorful modern pansies are hybrids, originally bred in the 19th century by English breeders who crossed several viola species to produce improved garden specimens. Desirable traits included large, overlapping petals and a wider range of colors and color combinations, including shades of purple, blue, reddish brown, yellow, white and gold. In the 20th century, orange was added to the color range and some varieties were bred specifically for enhanced winter hardiness.
To maximize the chances of winter hardiness, sow seeds in very early fall in sunny spots or install young plants in the garden at least a month before the first frost date for the area. This gives root systems plenty of time to develop. Mulch well with organic material. In areas with especially cold winters, grow pansy plants only in protected areas. A good rule of thumb is to plant pansies in the spots where the snow melts first.
With their short stems and bright flowers, pansies look best in pots or massed in the fronts of beds and borders. They are a lovely complement to spring bloomers like daffodils and tulips. In the fall, pansies get along nicely with garden mums and other traditional autumn plants.
Pansies grown in garden beds often have a better chance of winter hardiness than those grown in pots, because soil in all but the largest pots generally freezes more quickly than soil in the garden. Place potted specimens in a protected location, such as a screened porch or unheated garage, for best results.
Marketers sometimes suggest that only certain specially bred and marketed pansy varieties are winter hardy. Given the right conditions, many pansies are winter hardy, sometimes as far north as USDA Zone 5.