Temperatures have been fairly mild in many states this winter... which is good for you, but could cause problems for your plants. Frost heaving occurs when perennials are "heaved" out of the soil due to fluctuating temperatures. Specifically, when the temperature frequently switches between above freezing and below. The alternating freezing and thawing conditions cause the soil to expand and contrast, which then lifts plants up and out of the dirt. Roots are exposed to harsh conditions and become damaged. Your perennials could even dry out and die.
How do you prevent frost heave from damaging your perennial plants? Covering the soil with mulch is a good place to start.
Mulch helps insulate the soil to regulate temperature fluctuations and prevent the soil from expanding. There are several organic materials that can act as mulch, such as compost, pine needles, straw and leaves. Leaves are a great choice because they provide insulation while also allowing the soil to breathe. Add a layer to the soil about four to six inches thick.
If your plants are already beginning to heave, add soil around the base of your plant and then apply mulch to prevent further damage. Next year, you can take action right after the first hard frost to keep your perennials healthy and thriving.