The prevailing wind shifted over the last week, and we now have wind bringing cold air from the east, which takes a short trip north to bring down Artic air. This means it is cold, with temperatures reaching -6 degrees Celsius or 42 degrees Fahrenheit on the night I write this blog post.

After a warm October and November, the cold temperatures are a bit of a shock but welcomed as the cold has its benefits in the garden. The last few winters have been quite warm, with a few harsh touches of frost, leading to greater pest pressure and higher levels of diseases. The cold, particularly frost, helps control some illnesses and pests garden.

The cold can cause a lot of damage in the garden, but it also helps in other ways. Garlic uses the cold to know when to sprout, and other plants use the changing temperatures to know what to do. Apple, Plum and Pear trees need a period of cold weather to come into growth and blossom in the spring.

Herbaceous plants benefit from a period of cold weather by using the time to convert starch into sugar. During the cold, the plant will stop growing and die back. Unable to get energy via photosynthesis, they store carbohydrates in their roots which are stored as starch. The cold weather acts as a trigger for root enzymes to start doing their work. Starch is an essential energy source helping herbaceous plants with spring’s first growth and gives them a fighting chance to out perform annual weeds.

Biennial plants, such as the Sweet Williams I germinated this year, use the cold to know when to flower. The plant uses the cold to know when to start producing flowers in late spring and going to seed in summer. Bulbs also use the cold as a trigger to start growing, as do some seeds, such as sweet peas.

The colder months also offer an opportunity to plant dormant trees. Trees can be bought and planted with “bare-root”,, which can be a cheaper option for buying them. The dormant trees will grow roots in the spring and have a good chance of establishing before the drier summer months kick in.

While the cold, frost and frozen ground have reduced the amount of gardening that can be done, this is an essential step for the garden to enable spring to come and summer to be full of greenery and flowers.