If you are one of those lucky souls who look forward to a white Christmas every year, you have likely heard the expression: “snow is the poor man’s fertilizer.” While it’s the kind of phrase that gets kicked around a lot, have you ever wondered if there is any truth to it? Does snow fertilize the soil?
Like many “old spouse’s tales,” this bit of homespun folklore has a foundation of truth. Like expensive, store-bought soil fertilizers, snow in the garden can add nitrogen, sulfur and other trace elements to the soil. And since it penetrates the soil when it melts, it delivers the nutrients exactly where they are needed.
Let's dig in and explore just how beneficial snow really is for your garden.
Snow Adds Nitrogen
Yes, a new snowfall looks white and clean, just like in the old expression: “pure as the driven snow.” But scientists have established that it is not quite as pure as all that. In fact, as the water that will turn into snow falls through the atmosphere, it picks up trace minerals, including nitrogen which is notoriously good for plant growth. Nitrogen compounds include nitrate, dissolved organic nitrogen and ammonium.
Some of the nitrogen fixed in the snow comes from nearby lightning strikes. The rest is attributable to human activities, like car or factory emissions. Note that the initial flush of snow will have the most nutrients since, once the air is cleared, it takes time to build back up again. Altogether, rain and snow, taken together, deposit between 2 and 12 pounds of nitrogen per acre in the United States.
While the amount of nitrogen garden soil receives from snow is small, nitrogen delivered by snowfall has several important advantages. First, snow stays on the ground for some period, often some weeks, as it is melting. That gives the soil ample time to absorb the nutrients during snowmelt. Second, unlike commercial fertilizers, it is free to fertilize with snow and available to anyone living in a snowy area.
That is why it may be accurate to call snow the poor man’s fertilizer: it costs nothing and provides some nutrients. If you are interested in what nutrients your soil is lacking, try using a soil test kit like this one from Amazon. The amount of nutrients found in snow are very limited, impossible to calculate, and, all in all, inadequate to provide the soil all the nutritional help if it is majorly deficient. It does offer other benefits, however.
Protection and Hydration
You may not like the task of shoveling the driveway, but your garden benefits mightily from snow - in addition to adding nutrients. First, snow hydrates the soil. Although rain may be a quicker way of getting water to plants, much rainwater is lost in runoff. Snow melts gradually and is more likely to be absorbed into the soil, giving a needed drink to seeds, sprouts, and seedlings so they survive until spring rainfall.
In addition, snow acts like a winter mulch on the soil, a mulch you neither need to buy nor to apply. It falls on the soil without human help, then acts like a blanket, insulating the soil, moderating soil temperature and reducing the depth of any freeze. This benefits garden plants that remain in the soil over winter, including bulb plants and perennial plant roots.
Snow also protects plants from hungry animals, since a deep snow layer covers vulnerable lower branches and bark. A deeper snow pack also creates a safe zone in which smaller mammals can dig tunnels and travel distances without worrying about predators.
Soil Aeration and Winter Rest
Hard, compacted soil is not ideal for gardens. Loose soil makes it easier for plant roots to push their way down and seedlings to push their way up. Some farmers use soil aeration techniques to keep their soil loose enough to allow for microorganism activity as well as proper water and air circulation.
A blanket of snow can offer small but meaningful assistance with soil aeration. Melting snow seeps slowly into the soil. As it does, the water fills air pockets, reducing compaction, leading to improved root health and more microbial activity.
Finally, winter snow ushers in a period of rest for both the plants and the soil. With a snow fall and drop of temperatures, plants enter into their annual period of dormancy. This rest period - essentially a time out from growing - helps them save energy they might otherwise expend in producing stems and foliage, and invest what energy they have on root development.
Hopefully, this explained the benefits of snow for your gardens. Rest assured that you can leave that snow right where it is and it will work for you all winter long!
