Polytunnels are not attractive decorative features, but they can increase your produce by keeping your plants safe from the elements and extending the growing season. If you are a keen veg grower, a polytunnel can be a great help.
Heating a polytunnel
If you want to extend your growing season, it is essential to have the right amount of heating for your polytunnel during the winter. This will help to ensure that your plants stay warm and safe until spring. In colder areas, you should aim to keep the temperature of your polytunnel at a constant 55 degrees F, while in warmer climates, you should aim to keep it at 45 degrees F or lower.
There are a number of ways to heat a polytunnel during the winter. One way is by using bubble wrap. This is an inexpensive, convenient way to retain heat within your plants. Candles can also provide warmth. You can place them inside pots or in the soil of your polytunnel, and they will provide a surprising amount of warmth. Alternatively, you can cover your plants with a mini-cloche or small polythene tunnel, which will provide double insulation.
The plastic layer of a polytunnel is filled with air bubbles which trap the warm air inside. The larger the air bubbles, the more efficient they are at insulating the tunnel. This method can be used to insulate doors and windows, and it can also help you retain more heat within the tunnel. Moreover, it will also prevent the cracking of your ceramic pots.
Another method of insulating a polytunnel is to place rocks or stones in its corners. They will help retain heat during the day and release it at night, keeping the polytunnel a few degrees warmer. Alternatively, you can place a mini greenhouse inside the polytunnel, which will keep it warm.
Keeping plants from getting burned
When heating a polytunnel, you have to remember to maintain the correct temperature range. Higher temperatures can cause plant stress, which can lead to increased disease and pest problems. Heat can also cause weeds to overgrow, which can in turn harbor pests. The most common crops that grow well in polytunnels have specific temperature requirements, and if the temperature goes above this limit, your plants may be in danger of suffering. Fortunately, there are ways to keep your plants healthy during heat waves, including increasing water supplies.
Firstly, you can use shade netting to exclude sunlight during the hottest time of the day. You can also use shade covers to protect particular types of plants. In any case, prevention is better than cure.
Keeping condensation at bay
In the winter, you can reduce the risk of condensation by placing rocks around the edge of the tunnel. These will absorb sunlight and help to maintain the warmth inside. Another option is to use dark-coloured water in the tunnel, which will act as a heat reservoir. It will release heat slowly at night. Moreover, you can cover the tender plants with horticultural fleece or sheets of newspaper, which will help retain heat.
While snow can be a concern inside a polytunnel, it can actually help plants. It will act as a cloche and insulate the polytunnel. It will also keep the heat in the building and help to retain it. This method is also portable and can be used on your flowerbed or veg patch. You can also try lighting candles inside the polytunnel, which will also increase the temperature.
Growing crops in a polytunnel
Winter is a tricky time to grow crops, but a polytunnel creates ideal conditions for growing winter crops. It shields plants from wind, frost, and cold, which makes it possible to grow more crops in this climate. Some of the best crops for growing in winter are herbs, salad leaves, and lettuce. You can also grow winter vegetables such as potatoes. These plants can be sown as late as October. If you are planting potatoes, be sure to space them 20cm apart.
Many vegetables can be grown in a polytunnel, including carrots, parsnips, chard, and perpetual spinach. Carrots and parsnips should be direct sown into the polytunnel, while perennial spinach and leeks should be started in a seed bed. For early spring crops, such as onions and radishes, you will need to make a few amendments to the soil, and compost or manure can be used for this purpose.