When looking at the term crown hydration without prior knowledge, one might think that it's a good thing. With the crown being the central growing point of a turfgrass plant and hydration being essential for said plant, it would sound like a best-case scenario. However, this isn't the case.
In preparation for the upcoming winter months, turfgrass plants go through a process known as acclimation. Acclimation, also known as dehydration, means water moves out of the plant's cells through exposure to low but non-freezing temperatures and shorter day lengths gradually. So while the less water inside the plant when below-freezing temperatures are present, the less of a chance for ice crystals to form inside the cells.
In addition to this dehydration, there is an accumulation of carbohydrates and antifreeze proteins within cells. The carbohydrates are responsible for lowering the freezing point of water and serving as reserves to aid in regrowth in the spring. Antifreeze proteins can bind to the surfaces of ice crystals within cells to prevent or slow further crystal growth. All of these factors combined increase the fluidity of the cell membranes, meaning that they have more "give" and are less susceptible to freezing and bursting.
However, as daytime temperatures rise in the spring, turfgrass plants begin to de-acclimate. The problem with this process, especially in Maine, is that once we get a spring thaw, it rarely ever lasts. It is not unusual to have one week in the 50s and then be back to near-freezing and snow the week after.
Unfortunately, plants can't return to "hardened off" levels once it starts. Instead, the plants will uptake water in response to those warm days. Then, once the temperatures drop back to freezing or below freezing levels, our old friend intracellular freezing comes back into the picture and ruptures plant cells, causing the plant to die.