Insulation, heating, cold frame , garden cloche, agro textile and mulching are among the best methods to help you maintain a positive temperature inside the polytunnel in winter. As polytunnels extend the growing period, this represents a benefit for thermophilous and long maturing plants. On the other hand, cold-weather plants, with proper preparation in the garden greenhouse, can continue to grow, even if it is snowing outside.
Creating such suitable conditions is not a costly process and guarantees fresh and tasty vegetables throughout the year. For gardening enthusiasts, winter is associated with time off. Although many people think that this is an expensive luxury, year-round cultivation turns out to be economically advantageous.
So why not continue to cultivate in your polytunnel in winter and enjoy your hobby?
Tips to protect crops against frost and cold in your polytunnel
#1. Insulate with bubble wrap
This plastic layer contains air bubbles which keep the heat inside and limit loss of warm air. The larger the bubbles, the more light they collect, and the better the heating process. Just remove the snow from the tunnel systematically and this protection will reduce heat loss by up to 30%.
#2. Heat only one tunnel side
Sometimes it is not necessary to heat the whole facility. In case of large structures, this would generate huge costs. If there is a workstation with some delicate plants, you can use a frame or an isolating curtain. In the second case, it is important to install a sealed foil system to separate the heated fruits and vegetables from the non-heated. Another common solution is mini foil tunnels. These small structures are set up directly above the ground over plants that need protection against the cold. Such a double protective layer is the best choice to minimize heat loss.
#3. Add a cold frame
These miniature greenhouses are usually made of wood, with a glazed, removable top. The rear wall is higher than the front wall, and the window closes with a slight angle downwards. Such a design allows more light into the crate, raising the temperature inside. It is important to install such an object on an east-west axis to collect as much sunlight as possible. These are also used for sowing seeds during the year and preparing seedlings.
#4. Use garden cloches
Glass or plastic small domes with square or bell-shaped construction. These small covers are placed directly on the plants. As these are small items, they are only suitable to protect cuttings, small vegetables and fruit shrubs. Cloches are effective if there is a small knob at the top to allow air flow adjustment.
#5. Apply agro textile
This is a synthetic material that is applied directly on the ground so the layer slows down soil cooling. In addition, it limits the development of weeds. A hole is cut where plant are sown , to allow the upper part of the vegetable to emerge. This fabric contributes to more rapid and even plant growth. You can read more about it in this blog /en/cultivation-under-cover/agro-textile-in-foil-tunnel/
#6. Think mulching
It is a low-cost thermal insulation solution which can be dug and used as a compost inside the greenhouse. It is spread on the ground, evenly covering the whole area keeping it warmer on cold nights and cooler on hot days.. Unfortunately, it is not suitable for all crops, so it is worth checking whether this type of fertilizer is not harmful for the plants. Importantly, the main advantages of this method are: it is very cheap and widely available in rural areas.
What’s best to grow in a polytunnel?
Now that you know how to protect your crops during the cold months, you can focus on which species and their best growing methods. There is a wide range of vegetables able to cope with low temperatures. Always remember to take take into consideration your local environment. Take a look at your neighbours’ patch and see what works for them.
We invite you to follow our blog and website for regular updates and additional information on gardening under cover. You will find more on this topic in our blog: Winter crops in a polytunnel
You don’t need big investments to cope with the cold in your polytunnel. These tips can easily be implemented. It is not necessary to use all methods, but each of them helps retain heat for longer periods.
Even without additional heating, by combining several of the above mentioned methods, gardening in a polytunnel in winter becomes possible and can lead to surprising good vegetables harvests, packed with vitamines.
You can now experience with new crops and look forward to winter. A quality steel structure, straight from the manufacturer, will keep you busy during the so called off season. Gardening in a polytunnel just got better!