Finally, we are experiencing a real, deep cold (the teens, brr!) in Central North Carolina. There’s frost on the ground, on the trees, and on our vehicles; and a few ponds have even had a sheet of ice on them a couple nights this past week. Some folks worry about their plants and the nature around them being “cold” and “dying”, because we think that if we don’t want to be outside, nothing does. But, it is important in our climate for it to get cold in the winter, and the species of plants and insects that are native to our region adapt accordingly.
Dormancy
Dormancy is an annual period which causes the resting stage of a plant or ripe seeds during which nearly all manifestations of life come to an almost complete standstill, according to the Extension Gardener Handbook (2022). We see this as leaves fall from deciduous trees or our perennials retreat to a mere crown of leaves just above the soil line. Their development is slowed down significantly, and only parts of the plant senesce, or die and slough off; but the main crown and roots of the plant is still alive!
This period helps plants and animals survive through less than ideal conditions and also helps regulate the cycles of life. Some plants and animals need a cold, wet period, like our winters, in order for their seeds to germinate. Without the right length of cold or a certain drop in temperature, the seeds will not germinate. This is also important for the flowering of our favorite fruit trees, like apples and peaches. If it gets too warm too soon, that is why we see the flowers come out too early! Dormancy is not only a winter phenomenon though; there are some organisms what will be dormant during the summer heat!
Diapause
Diapause refers to the state of arrested growth or reproduction that is typical of many hibernating or aestivating arthropods (Legner, see website references). It is a little more than the traditional definition of dormancy. The chemical underpinnings of this biological process are slightly different. Many insects and other animals experience this physiological phenomenon, and it is a natural part of the changing of the seasons and year. What is important to note is diapause is slightly different for every species, but many species undergo diapause at certain times of year, whether or not the weather is ideal. When their diapause cues do not align with ideal weather conditions, some animals can have reduced survivability because they have to use energy to protect themselves from the climatic conditions.
Death
Death is a natural part of life; so cliches aside, it is healthy to expect death to happen to the life around us. Winter temperatures can kill tender plants and animals that cannot stop the water in their bodies from expanding. This cycle of life makes way for the next generations to germinate, grow, thrive and reproduce. It is a way to reduce poorly-adapted genetics within plant and animal species, so more well-adapted individuals can grow.
Some species are annual species and complete their life cycles in one year or one season. Some of these species can even have multiple generations in a year or season. This quick cycling of generations selects for adapted individuals for certain growing conditions. When we have long falls or warm winters, some of these species can have more than their usual number of generations. This usually makes weed control challenging!
You can reduce or prevent dead using winter protection on marginally-hardy plants. Winter protection can be as simple as using mulches, leaving the leaves, and throwing a piece of fabric. Even a little bit of fabric can add a couple of degrees, which can be the difference between life and death. You can go to your local landscape or farm supply stores and get different thicknesses for different purposes. Most of our native plants don’t need to be covered though. It is more of a worry with leafy vegetables, like lettuce and Brassicas, like broccoli and kale.
Amanda Bratcher is the Horticulture Agent for North Carolina Cooperative Extension in Lee County.
