As Scotland emerges from our early March run-in with the Beast from the East and we start to see the green breaking through the white, is this the time to worry about what damage has gone on underneath the layer of Narnia melting before our eyes?
Snow cover, believe it or not, can actually be quite beneficial for the trees and shrubs in your garden. Snow acts as an insulator from cold temperature extremes, providing protection a little like an igloo. Cold weather, particularly frost, can cause the water in plant cells to freeze, damaging the cell wall. Frost-damaged plants are easy to spot as their growth becomes limp, blackened and distorted and evergreen plants can turn brown. Cold temperatures can freeze the ground deeply too, which can damage the root systems of shrubs and trees. A blanket of snow cover snuggles the plant and can also give protection from harsh, drying winter winds.
Secondly, snow can help reduce the loss of moisture, especially in evergreens as even in the cold months of winter, drying winds evaporate moisture from the needles and foliage of evergreens. Hardy plants and tough evergreens can be damaged by prolonged spells of severe cold when the soil becomes frozen and plant roots are unable to take up water and plants can die from lack of moisture, even in Winter. As the covering of snows begin to melt, moisture is provided to the soil to help new growth expand.
Much of the damage caused in our gardens when it snows is actually as a result of repeated freezing and thawing. Alternate freezing and thawing of the soil pushes shallow plant roots out of the soil, sometimes known as soil heaving, leaving roots exposed to cold, drying winds as well as damaging susceptible flower buds. Poorly established or shallowly rooted plants such as strawberries and chrysanthemums can be prone to heaving. Many of these effects can be counteracted by applying a thicker layer of mulch like bark, wood chips or shredded leaves around shallow rooted plants towards the end of Autumn ahead of the cold, Winter spell. As temperatures warm up in the Spring, be careful to keep mulch pulled slightly back from the crowns of perennials that are susceptible to rot. A cover of several inches of snow is a good insulator against the freeze and thaw cycles that heave plants out of the ground. The process of freezing and thawing itself indeed has been said to improve and lighten soil structure making it easier for plants to root and therby increasing productivity.
Snow has even been referred to in the past as the poor man’s fertilizer and this is not just an old gardener’s tale. The science behind that is that as snow falls through the atmosphere, nitrogen and sulphur attach to the flakes. When the snow melts, these elements are released into the soil and absorbed by plants. Nitrogen in particular, is essential to plant growth.
Certain plants actually need a cold period before setting into growth and a ground covering of snow will also cool Spring bulbs like daffodils and crocuses, often just delaying not damaging their blooms. Roses are even said to flower better after a hard winter and apples and pears set more fruit.
So if you have been despairing over the last few days as you’ve watched your garden sink under a descending Narnia, fear not, Mother Nature has indeed provided many benefits to the life of your flora under a beautiful blanket of white, you just cannot yet see the glory!