Frost heave is what happens when the ground thaws and freezes alternatively, developing a water source below the surface that freezes towards the cold source – meaning that the ice grows up towards the surface, pushing the soil around as it grows. What this causes is an ice lens that can lift soil or, in severe cases, even solid surfaces such as concrete or pavement. This creates a hazardous environment that can be deadly to plants and lawns.
A frost heave is not something that can be prevented, but it is something that can be mitigated. Hardscaping, such as decks and other structures, can be protected against frost heaves by sinking the supports below the frost line. This will keep the base of the structure from being pushed up or from sinking down with the creation or thawing of frost.
Hardscaping is not the only thing effected by frost heaves. Soils, especially those that are particularly loamy or silty, are extremely vulnerable. A frost heave in a soil made up of particulates that are extremely fine will cause a bubble, then a collapse. This will cause hills and dips in the lawn, creating an uneven surface. In the most severe cases, this can cause sinkholes.
A frost heave can also be detrimental to plant, especially perennials that tend to be loosely rooted in the soil. A loosely rooted plant will have the roots pushed to the surface or even torn apart by a frost heave. This will happen most often to plants that are placed in an exposed location. To prevent a frost heave from claiming a perennial, make sure the plant is shielded from snowfall. Concentrated snowfall tends to cause the most severe frost heaves, as the melting and subsequently freezing precipitation makes the areas of snowfall perfect grounds for this malady.
To protect against frost heaves, check the composition of your soil and adjust accordingly. Soils made up of denser substances such as clay tend to have less of an issue with frost heaves. While this may not be a possibility for the majority of your lawn, as you have to work with what you are given, this is definitely something to be taken into consideration in regards to sinking hardscaping into the ground or planting flowerbeds. Changing the soil or providing shelter to these planned changes to your landscape can keep them from being pushed around or, in the case of plants, killed by this winter hazard.