Pansies (Viola x wittrockiana), cheery and bright as they are, add a low-maintenance pop of color to gardens and look great in vases or pressed flat for craft projects. Determining if your particular pansy plants will die off or grow back can be tricky because pansies grow differently from zone to zone. Depending on where you live, and the type of pansy you plant, the pansy can be an annual, a perennial or a biennial.
In their natural state, unchanged by science, pansies are biennials. They grow leaves their first year, flower their second year, and then die off. Biennial pansies might not survive harsh Midwestern winters or especially hot Southern summers, meaning they'd likely die off after one growing season. On the West Coast, in places such as Southern California, biennial pansies can survive all year long, and new plants will return the following season to flower and finish out their growing cycle.
If you purchased pansies that have already flowered, such as those sold at garden centers, you should treat them like annuals. Most commercial pansy plants are actually hybrids that grow in one season, then die off, according to Washington State University. If you do purchase flowering biennial pansies, they'll also work in your garden as annuals. Since they've already flowered, they're in the second stage of their growing cycle and will die off at the end of the season. Hybrid pansies and pansies purchased in the second year of their growing cycle can grow from spring to fall in any plant hardiness zone.
There are no true perennial pansies that return year after year and flower. If you have pansies that act like perennials, they're actually re-seeding annuals and biennials. Annual and biennial pansies can act like perennial pansies in consistently warm climates, such as those in zones 9 to 11. Because there's no severe cold to push the plants into a dormant period, they can go to seed, drop their seeds and those seeds can grow the following year.
Pansy blooms won't survive harsh temperatures. They prefer average daytime temperatures of about 60 degrees Fahrenheit and nighttime temperatures warmer than 40, according to the Washington State University Cooperative Extension. For this reason, they're planted for spring or fall blooms in most of the United States. If you live in a region with delayed or no frosts, you can plant pansies into the winter. If you live in a colder climate and wish to enjoy pansies in late fall and early winter, grow the pansies in containers so when temperatures dip below 35, you can bring them indoors where you can continue to enjoy these pretty flowers.