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Did you know that plants have a mechanism to 'harden' themselves, allowing them to survive the cold winter?
The vitality of plants is amazing, especially their resilience in the face of harsh climates. This resilience is often referred to as "hardiness," which refers to a plant's ability to survive adverse growing conditions, usually associated with climatic adversity. Plant hardiness mainly describes their resistance to extreme temperatures, such as cold, heat, drought, flooding or strong winds. This ability is of great importance in agriculture and horticulture, as choosing the right plant varieties is related to the balance of the entire ecosystem and the production of crops.
The definition of hardiness is closely tied to the native geographic location of the plant, including attributes such as longitude, latitude, and altitude, which are often simplified into a hardiness zone.
Winter Hardiness
Winter hardy plants are able to grow through the winter, or at least remain in a healthy dormant state. In addition to hardy evergreens, there are many improved crops, including different varieties of cabbage, cauliflower, and various carrots.
Some bulbs, such as tulips, require cold winters to flower, while others, such as African violets, can survive freezing winters. To facilitate winter gardens, many plants are designated as cold-hardy, which allows them to grow in harsher climates.
Self-hardening mechanism of plants
Woody plants face freezing temperatures by inhibiting ice formation within living cells or by allowing water to freeze in parts of the plant not affected by the freeze. Many woody plants are able to survive down to −40 °C (−40 °F) using a supercooling mechanism, while those that can withstand lower temperatures dehydrate their cells, causing the water to freeze between the cell walls and the cells to survive.
It is important to note that plants, even those considered cold-tolerant, may not survive in cold environments without adaptation.
Cold Resistance Rating
In the United States, the most widely used hardiness rating system is the USDA hardiness zones, which are based on the average minimum annual temperature. The system was created specifically to account for the diverse climate conditions across the United States. Another commonly used system is the Sunset Climate Zone System, which divides climates based on factors such as precipitation, temperature, and humidity.
In the UK and Western Europe, due to the influence of the marine climate, the temperature range is relatively narrow, so more targeted cold resistance evaluation standards have been developed to facilitate plant selection and planting in a changeable climate.
Highlight the economic value of plants
Cold-tolerant plants are important not only for their ecology but also for their economic value. Generally speaking, hardy plants can withstand a variety of extreme temperatures and harsh environments while being low maintenance, making them an excellent choice for agricultural production. For example, plants such as burdock and mulberry have shown good adaptability and have become financially important crops.
Other tolerance factors
In discussions of cold hardiness, the ability to tolerate other climate factors is often overlooked. For example, heat tolerance and drought tolerance are both areas of concern. Tropical plants can grow in hot environments, and some plants can survive in environments with little water.
The mechanisms of wind tolerance still need to be further explored because wind not only causes mechanical stress but also makes plants colder and drier.
The hardening ability of plants is related to the stress they experience during the growing season. If the stress is too great, the plants' tolerance to winter cold tends to decrease. The drastic temperature fluctuations caused by climate change may also affect the survival of plants.
So, when faced with climate change and the challenges it brings, how should we select and cultivate more suitable plants to protect and restore our ecological environment?
