There are several ways to heat a polytunnel in winter. One option is to place large rocks at regular intervals along both sides of the polytunnel. These will absorb the sunlight and retain it. Another option is to use a hotbed.
Polytunnels are a great way to keep your crops warm throughout the winter. Whether your polytunnel is large enough for all your plants, or small enough to grow only some plants, there are ways to heat your polytunnel. These methods are simple, cost-effective, and can help you keep your plants growing even in the coldest months of the year.
Polytunnels are typically heated by solar radiation, which warms the plants inside faster than the heat can escape. The walls and roof will also keep heat in. This helps you grow plants that need warmer temperatures than those grown in glass greenhouses. Ideally, you should start planting early in the spring to ensure the best possible germination conditions.
Then, cover the polytunnel with bubble wrap. Use cable ties or string to secure it to the walls. The bubble wrap should be UV stabilised.
Using a polythene cloche
Using a polythene clche as a cover is an excellent way to keep your plants protected in winter. The plastic cover also helps to prevent pests like pigeons from eating young plants and carrot rootfly from damaging your crops. It also helps to keep butterflies and caterpillars from laying their eggs on your crops.
Using a polythene clche acts like a double glazing, giving extra protection against harsh weather, while keeping heating costs down. It is easy to move and remove and is incredibly effective at retaining heat. If you want to increase the temperature of your polytunnel further, you can light a couple of candles inside it.
A polythene cloche helps to raise the soil temperature and protect seedlings from the cold during the winter months. This can help extend the cropping season. It can also help prevent the loss of heat during the night and help plants germinate faster.
Keeping plants protected from insects
Heating a polytunnel is an effective way to extend the growing season. By keeping the temperature of the polytunnel higher than the surrounding temperature, the growing season can be extended, keeping summer crops alive into the autumn months. Polytunnels can be heated with conventional heating systems or with environmentally friendly options such as a wood-fired hot water heater.
A polytunnel is an enclosed structure, so it is important to use ventilation to remove excess heat and regulate moisture. While plants have a natural ability to dry out and transpire, insufficient ventilation can cause excess moisture and the appearance of harmful insects.
One of the most effective ways to protect your plants from insects is to use garden fabric. This material can help protect your crops from common pests and weeds. It should cover all of the plants completely and be pinned to the ground. It can protect against aphids, leaf miners, cabbage worms, root maggots, and vine borers.
Using a hotbed
One way of using a hotbed to heat a polytrench is to fill it with stable straw or fresh manure. This will decay and produce heat. Traditionally, the hotbeds are covered with six inches of sieved fine soil. Hotbeds can also be filled with old manure, compost or decomposed straw.
To build a hotbed, you need a frame made of wood or pallets (three EU-pallets are enough). A layer of compost mesh should be spread over the manure. The ground should be well-drained and the hotbed should be built on a high, well-drained area.
To test its temperature, you should place a thermometer inside or outside the hotbed. The digital thermometer should be placed on the outside of the hotbed, to prevent condensation. When the temperature reaches a high enough level, the composting process will begin.