The recent warm temperatures and spring rain have driven away what is left of this year’s dumping of snow. Although our plants have been dormant and waiting all winter, cues like snowmelt let them know that it is time for the growing season again!
One study from 2022 (Zheng J. et al, 2022. Agricultural and Forest Meteorology, Volume 315) examined how snowmelt impacts the start of the growing season. The authors noted that the three main drivers of vegetation phenology are soil moisture, soil temperature, and sunlight—all three of which are largely influenced by snowmelt in predictable ways. A large amount of the snow that melts sinks directly into the soil beneath, greatly increasing the amount of water in the soil. Also, when the snow melts, sunlight can reach the soil below. That extra sunlight will also increase the temperature of the frozen ground. So during snowmelt, soil gets wetter and warmer, indicating to sleeping plants that it is time to start growing again!
Early snowmelt can also be dangerous for plants. Plants rely on the huge amounts of water from snowmelt to grow, and if snow melts too early, there is a risk for drought before spring and summer precipitation. Also, in years when there is only a bit of snow on the ground, a random week of warm temperatures can melt all of it, removing the snow’s insulating effect and exposing the ground to freezing temperatures. Dormant plants can be damaged before they even have a chance to start growing. Fortunately, with the amount of snow we received this year, it doesn’t seem like that will occur this growing season.
It’s easy to see how snowmelt impacts the start of the growing season, because these two events occur back-to-back. However, snowmelt may have some longer-reaching effects throughout the whole year!
A study published this January (Powers J. et al, 2025. New Phytologist 245: 332–346) explored how the timing of snowmelt impacts floral characteristics, nectar production, and especially scents emitted by flowers. Over a three-year period, the authors found that timing and amount of moisture in the soil did have an impact on many factors during the growing season. Lower moisture content in the soil caused by early snowmelt and halved precipitation decreased the size of many parts of their study flower, such as the corolla, style, and sepal. Lower moisture content also decreased the production of nectar, but the concentration of nectar increased.
Floral scents, also known as volatile organic compounds, were affected as well. These volatiles consist of many different chemicals mixing together to create a cocktail that attracts and repels certain insects. Certain classes of volatiles were affected differently by moisture content in complex ways. There was a lot of variation in the amount of volatiles emitted, because moisture changes can happen quickly and in small areas. Because of this, they were only able to explain 5-13% of the emission variation with moisture changes.
Figuring out how limited resources like water affect scent changes or flower characteristics is tricky; it’s possible that scent is more impacted by drought because it is faster and easier to change chemical reactions that make and release volatiles. It takes more time and effort to build parts of the flower. However, the opposite may be true, in that large changes in floral characteristics can be so costly that they are more impacted by depleted resources.
As you can imagine, changing the chemical cocktail of volatiles emitted will impact which insects are attracted to and repelled by the flowers. These changes can be both good and bad, because flowers are visited both by pollinators and seed predators. So it is possible that on a large scale, early snowmelt can shift the entire evolutionary fitness of a plant.
This study is one of many that just scratches the surface of complex interactions between plants and the environment. It is impossible to know all of the far-reaching effects of climate change, even those caused by something as early in the growing season as snowmelt. We’ll be following the science and keep you posted as we expand our learning!
