From towering pines to lesser-known yellow aconites, these plants promise to add evergreen leaves and colored flowers to our cold winter.
Although wintertime can bring hard feelings, the color and dimension plants provide can help minimize depression and anxiety associated with winter.
Therefore, to help you get through winter with more peace and tranquility, we are providing different types of winter plants to consider, how they survive, and we are highlighting some of our favorites. These plants can grow outside in forests during winter, or you can add some of them to the landscape around your house.
Types of winter plants
Plants have a wide range of low-temperature tolerance. We can classify this tolerance according to the cold hardiness. Cold hardiness is the ability of plants to survive subfreezing temperatures, and we can group the plants according to the degrees under zero these plants support (Bañuelos et al 2008).
- High hardiness level: Two main groups of plants have evolved to support cold temperatures between -10 to -20 °C. They are evergreen and deciduous trees. Evergreens are trees that do not lose their leaves in winter, while deciduous trees do indeed lose their leaves. Examples of evergreens include some pines, while deciduous trees include maples, oaks, and beeches. Trees like aspens can survive at temperatures as low as -196 °C, which is almost unbelievable (Bañuelos et al 2008).
- Intermediate hardiness level: Here, plants can survive temperatures as low as -5 to -10 °C. Among these plants include certain varieties of wheat and rye.
- Low hardiness level: Plants in this group can survive low temperatures between 0 to -5 °C and include varieties of potatoes.
Plants adapted to low temperatures of -10 to -20 °C: Tough winters
Majestic pines and evergreens
Different pines include, Douglas fir, balsam fir, blue spruce, Fraser fir, Norway spruce, Scotch pine, white pine, and white spruce.
How do pines remain green during the winter? It is all thanks to different mechanisms these plants developed to survive freezing weather. There are six mechanisms that we will highlight.
- Small leaves: Pine needles are pointed leaves with a small surface area to reduce water loss through transpiration.
- Internal stomata: Stomata is the structure within leaves that opens and closes to facilitate oxygen exchange and the entrance of carbon dioxide for photosynthesis. The stomata are on the leaves' abaxial side (lower surface) in a typical plant. However, in evergreens, the stomata are deep within the pine needle. This creates a pocket of air that allows less transpiration and facilitates air movement.
- A waxy coating: Pine needles also have a waxy coating protecting them from drying winds.
- Thick bark: This is the external layer that covers shoots and roots in woody plants. This tissue protects the tree from disease, insects, storms, and extreme temperatures.
- Ice proteins: Internally, plant cells accumulate proteins that help them deal with frozen water. Ice can damage the cells; thus, these proteins equilibrate the internal and external environment with frozen water. These proteins also help prevent ice crystal formation during cold temperatures.
- Cones: Cones are the reproductive structure of some evergreens like pines. These cones protect the seeds from hard winters.
All these adaptations made the majestic pines a winter resistant plant. Furthermore, their rustic yet beautiful hanging cones signal the season and make lovely decorations.
Deciduous trees, such as oaks and maples
The bare trees that we see during winter are deciduous. Oaks, maples, and beeches, for example, have evolved to deal with wintertime and save energy.
Like evergreens, deciduous trees have developed different mechanisms to support the winter. Some of them are shared with evergreens, and others are specific to deciduous trees.
Some deciduous trees, have also developed hard cones to protect their seeds and a thick bark similar to evergreens.
What is different about deciduous trees is their capacity to lose their leaves around wintertime. The technical term for losing leaves is abscission.
But why do these trees lose their leaves? The reason is that leaves are a significant source of water loss, so deciduous tree species drop them in the fall before winter. Furthermore, without leaves, photosynthesis is stopped, and internal movement of water and minerals from the soil is not necessary.
Leaf-drop involves pulling exudates out of the leaf and then forming a thin layer of cells where the leaf will eventually break off.
Of course, the colorful fall season is the most prominent part of this process.
There is an acclimation period to the cold weather called dormancy for evergreens and deciduous trees. In dormancy, all biological processes of trees slow down, allowing them to survive four or five months under the harsh winter.
Plants adapted to low temperatures of -5 to -10 °C: Very Cold weather
Wheat and rye species can support freezing temperatures as low as -5 to -10 °C.
There are two wheat varieties: spring and winter wheat.
The winter wheat variety can withstand freezing temperatures for extended periods during the early vegetative stage. This plant variety requires exposure to freezing or near-freezing temperatures to trigger the reproductive stage. Unlike other species, winter wheat plants require a cold period before the reproduction stage.
The growth stage or maturity is probably the most critical factor to support cold temperatures. For instance, if the wheat plant is already in the reproductive period (the pollination begins), this will make the plant more sensitive to low temperatures. So, cold temperatures are better supported in vegetative stages.
Dr. Tanino of the University of Saskatchewan led a study of the vegetative crown (Fleury, 2020). In these winter cereals, the vegetative crown is a modified stem, which is a crucial organ that survives the winter. Important results of her research indicated that although the leaves and roots eventually die over winter, if the crown is alive, then the plant can regenerate new roots and shoots in the spring.
Furthermore, Dr. Tanino also identified that the ability of the plant crown to withstand prolonged exposure to low temperatures could vary between different genotypes, with winter rye being the most cold-hardy, followed by winter wheat, winter barley, and then winter oat.
Plants adapted to low temperatures of 0 to -5 °C: Cold weather
Potatoes can survive a light frost between 0 to -5 °C, usually with little or no damage. Although the cold may damage potato plant leaves and stems, and in some cases, new shoots can emerge from seed potatoes underground and continue growing.
Usually, the presence of black edges (margins) on the leaves means the cold weather is damaging potatoes.
Two key factors determining whether a potato plant will survive harsh cold temperatures are:
- The cold severity, or how far below freezing the air temperature is.
- The length of exposure, defined as how long the plant was exposed to the cold.
Furthermore, to increase potato survival, many farmers use row covers to protect potato plants against the cold. In developing countries, people use torches to reduce the increase the temperature when frost occurs.
Frost consists of the drop in ambient temperature to levels below the freezing point of water. It causes the water or steam in the air to freeze and settle in the form of ice on surfaces.
Colorful plants for wintertime
Although winter can seem a bit gray and sad, there are winter plants that help raise our spirits.
Below is a collection of plants that flower even in the dead of winter, and they are ideal for improving our wintertime mood.