Pansies are chosen as spring and fall bedding and container plants for their colorful blooms and cool weather tolerance. In mild climates and partially-shaded beds, pansies may bloom all summer long and well into winter. Winterizing pansies gives them the best chance to survive freezing temperature and burst forth with new blooms on warmer winter days. It also prevents disease from over taking the beds and spreading to your pansies or the next flowers you plant in the area come summer.
Push any mulch off the bed and out from under existing pansies. Dispose of the mulch if disease is a concern or set it aside until you are done preparing your beds if you wish to re-use it.
Remove all dead and dying vegetation from summer annuals from the bed. Dig up old roots and discard along with other garden detritus.
Trim back existing pansies. Cut each stem back to 3 to 5 inches, leaving the leaves at the base of the plant intact.
Apply a slow-release fertilizer if daytime temperatures are still above 60 degrees Fahrenheit. Apply a liquid nitrogen-rich fertilizer every two weeks if daytime temperatures are lower.
Replace the mulch around the pansies or apply a layer of fresh straw or small bark mulch. Avoid covering the the foliage with the mulch.
Water as needed, allowing the soil to dry out slightly between watering once temperatures drop below 60 degrees on average.
Cover pansy plants completely with a 4-inch layer of straw mulch during extended periods of temperatures below 20 degrees. Remove the mulch once the weather warms up.