To grow pansies in winter, it is important to pick cold-hardy varieties called winter pansies. One of the best tips for growing pansies in winter is to space the plants closer together than the suggested spacing for spring-planted pansies. This creates a dense cover of flowers without areas of bare soil showing. A layer of mulch after the fall planting is a good tip to help regulate soil temperature and provide insulation as the cold weather descends. Fertilizer can be applied in late winter, but spreading it at planting time is just a waste of materials because the plants won't put out a lot of new growth until the spring.
Winter pansies bloom all winter in mild climates. They can withstand some frost and light snow without damage to the plants or flowers. In areas that have long, cold, snow-covered winters, pansies will go dormant under the snow during the harshest months of winter, but they bloom all fall, right up to the first snows, and they come back early in spring as soon as the snow starts to melt off.
One of the best tips for planting pansies in winter is to space the plants close together. Summer blooming pansies grow vigorously and fill out an area, so they can be spaced farther apart. Winter pansies should be spaced 4 inches (about 10 cm) apart to create a full, lush ground cover.
The small-flower varieties are the best to choose when planting pansies in winter. Large-flower varieties tend to get weighed down under rain and light snow more quickly than small-flower varieties. Pansies are effective as bedding plants in border areas and large planters.
Winter pansies still need sun, so one of the best tips when planting pansies in winter is to select a sunny spot. After planting, a 2- to 4-inch (5- to 10-cm) layer of mulch should be spread over the garden bed. This creates an insulating layer over the soil that slows freezing and thawing. When the ground freezes and thaws rapidly at the beginning of winter, it can cause the ground to heave and disrupt the pansy root system. Fertilizer can be applied in late winter when new growth begins.
In mild, wet areas, slugs should be monitored closely. They can be picked off by hand as they appear. Slugs can quickly damage the delicate leaves and foliage of pansy plants.