Living in a colder climate doesn’t mean you need to give up on more fragile plants. By adequately preparing your less-hardy plants for the winter, you’ll set them up to survive and thrive!
Here is a sample from Cold-Hardy Fruits and Nuts Scott Serrano & Allyson Levi. It has been adapted to the web.
Plants that are protected from winter elements
Anyone who has been gardening in the north of the United States for several seasons knows that each season is unique because of the weather. Each season is similar to the previous year, but no two seasons are alike.
Snowfall can vary greatly from one winter season to the next. Some seasons are marked by massive amounts of precipitation and unusually cold weather. Others may bring only a few centimeters of snow. The plants in your garden are affected by the combination of elements such as snow, wind and temperature.
Those readers who live where winter temperatures do not fall below 10°F (−12°C) might not need to worry as much about the winter protection measures listed below. Winter damage can be a problem for young trees and shrubs that have only been in the ground a short time.
Protecting Different Types Of Plants
Some plants can withstand the harsh winters, but others may require extra protection for a few years. These suggestions are for single trees or multiple plantings which would benefit from an extra year or two protection before they are exposed to the full effect of a northern summer.
It may seem excessive to lavish extra care on newly planted plants during the winter months. Protecting a young plant, which may not be fully hardy, can vary from doing nothing up to building a small temporary enclosure. The options listed below are ranked from easiest to most difficult.
Protective Mulch
Mulch over the root system is the easiest way to minimize the negative effects that low winter temperatures have on young plants. Any mulch of mixed wood chips or shavings will cushion a young plant’s roots against winter temperatures. This extra mulch can be piled high against a plant’s trunk or branches for protection as an insulation blanket over the root system.
The excess mulch is then removed in the spring and spread in an even thin layer to cover the roots. Because thick layers of mulch provide cover for small rodents, it’s important to use a protective tree collar so that animals cannot damage the new plant.
Winter Sunscald
Woody deciduous plants survive the winter months by going into a period of dormancy—the state in which a plant is alive but not actively growing. The combination of autumn cold and shorter day length triggers this. As the daytime temperatures start to warm up towards the end of the winter, deciduous trees can begin to awaken from their winter dormancy. This can cause serious damage.
The warm temperatures of the day cause the sap to melt near the roots and rise up the trunk towards the buds at the end of the branches. Because it’s winter, though, nighttime temperatures can still drop below freezing.
Sap & Sunscald
The sap can freeze suddenly before it has time to return to the roots. When the temperature increases, the frozen sap trapped in the trunk expands and splits the trunk under the pressure. The southwestern or sunscald syndrome is the result of cracks running down the bark on a plant’s side that is exposed to the most sunlight, usually facing southwest.
The sunscald most commonly affects young trees that have long, thin trunks and flexible bark. These trees are usually planted in areas that receive full sunlight facing south or southwest. Traditional methods of treating this include painting young trees’ trunks with a thin coat of white paint that has been diluted with water.
Painting Tree Trunks
The theory is that the young plant’s white-painted bark reflects sunlight away from the trunk, slowing the warming of the tree’s sap. Take water-based white house paint and thin it with water at a ratio of 1 part paint to 4 parts water, then apply a few thin coats of paint from the tree trunk’s bottom to the first major branches.
The primary drawback is that the tree’s bark will look chalky white and less aesthetically pleasing. The paint will fade over time, but as the plant matures, it is less likely to split.
Wrapping plants
Wrapping plants in burlap is a traditional way to protect them. Burlap will offer some protection against the cold. However, it’s best to use this method at sites with extreme wind conditions. The branches of the plants may be damaged as a result.
This method can be used to protect shrubs that are planted close together in a fence. Wrap the burlap tightly around the sides of your hedge as a protective layer to protect against heavy snow loads.
Tenting
To create a mini-greenhouse during winter, you can build a temporary tent to cover a shrub or tree. A protective tent enclosure can be a simple “tepee,” formed out of thin wooden posts or bamboo stakes driven into the ground and tied together on top. Then, wrap a transparent sheet of plastic around the entire structure.
Remove the covering as soon as the weather warms up. Any warm space that protects a plant can also be a warm space that protects small mice or voles. These creatures may chew on lower sections of a plant. Consider using a vole-proof cover to protect your plants if mice and voles pose a problem for you.
Greenhouse
A greenhouse/hoop house is the best winter protection option for growing plants at cold northern latitudes. Because a greenhouse interior can be 10 to 30°F (5–17°C) hotter than outside temperatures in the daytime, a greenhouse lengthens the growing season. A greenhouse protects plants from the cold weather, but also provides protection against wind, snowfall and icy conditions. Even though greenhouses can be expensive to construct, they last for many decades and provide you with a consistent harvest over a long growing season.
The commercially produced greenhouse kits come in many sizes and designs. In a non-heated greenhouse, the temperature is higher than in the surrounding area. This allows plants from marginal zones (one zone hotter than yours) to thrive and produce fruit. Fruit trees can grow in a greenhouse despite the size restrictions. Pruning and management are key to ensuring that they survive and bear fruit.
Recommended Reading
Winter Growing: Low Tunnel Tutorial
The Sweetest Winter Carrots