Winter is certainly setting in and mornings of glistening frost and a biting breeze are becoming more and more frequent. Temperatures in your polytunnel may be starting to dip below freezing. Never fear though, there are some tried and tested ways to keep young, tender plants snug and warm until spring arrives. 

Electric Fan Heaters

Polytunnel heaters come in many shapes and sizes, and each have their pros and cons. Electric fan heaters for polytunnels are readily available at a reasonable price; they can be set to oscillate to spread the heat around, many have a thermostat built in, so it will only turn on when the temperature dips. This can be cost effective and and it takes away the need for you to go in and check that you haven't roasted your plants. It does require an electricity supply, however, which may not be accessible for all plots.

Paraffin heaters

A big advantage over paraffin is that they are usually supplied with thermostats, so they can be set to come on only when needed. The advantage over electric heating is that it does not need to be connected to an electricity supply. The downside is parafin heaters can be expensive to run and they expel fumes and water vapour.

Bubble Film

Bubble film can be fitted to your polytunnel hoops with specialised hoops, or lines of string secured in between your hoop spacings. There is no set technique to fitting bubble film, some clothing line and pegs and that will usually do the trick. Make sure your bubble film is UV stabilised and the bigger the diameter of bubble the more light can transfer through to your plants. This is a great way to keep your plants warm, but is only effective in miilder winter nights.

Horticultural Fleece

A layer of frost protection fleece will provide protection from cold winds and frosts and is often used for covering cloche hoops, mini polytunnels and cold frames. You will also find it helps to warms up the soil by simply adding multiple layers of fleece. Tip: Remember to remove the fleece during the day to ensure the plants receive adequate ventilation and light.