Learn How to Heat a Greenhouse in Winter | Onduline

If you invest the time and energy to build a DIY greenhouse, it would be a shame to leave it empty for several months of the year. Unfortunately, even seasoned gardeners may be under the impression that they can’t grow anything during the winter due to the cold and moist conditions. However, you can use your greenhouse all year around if you follow these tips to keep your greenhouse warm in the winter.

Ideally your greenhouse is already in a location where it collects the maximum amount of sunlight. However, during the winter months, the sun’s trajectory is lower in the sky, so trees and buildings that are not an issue in the summer might cast shadows during the winter time. If possible, remove any objects that create shade on your greenhouse. Pay close attention to the roof and prevent snow or leaves from accumulating. Use a leaf blower or broom to remove anything that does not naturally slide off your roof.

When researching how to heat a greenhouse in winter, you may come across a lot of heaters. We will discuss the benefits of heaters later on, but first let’s talk about an affordable option that does not require electricity. A heat sink, also known as a thermal mass, is an easy and inexpensive way to warm a greenhouse. To create a heat sink, gather one gallon plastic jugs, paint them black on the outside, fill them three-quarters of the way full with water, and place the black water jugs throughout the greenhouse. So, how does a heat sink work? The jugs of water absorb heat during the day and release it during the night. The heat sink will raise the temperature in the greenhouse by one or two degrees. This temperature change is small, but can easily be the difference between frozen and happy plants.

If you are wondering how to use a greenhouse in winter, it may be useful to know that many winter gardeners love to use their greenhouses to start seeds during the cold months. If you are looking to get a head start on your spring plants, your greenhouse may benefit from a germination mat. A germination mat, also known as a heat mat, is an electric mat that goes underneath a seed starter tray to keep the sprouting plants warm. Germination mats help vulnerable plant roots maintain the optimal temperature and increase the early-stage growth rate.

A classic way to keep your greenhouse warm during the winter is to cover up your plants. This practice involves gently laying sheets, blankets, tarps, or horticultural fleece on your plants, particularly on cold winter nights. The covers trap the heat inside to keep the plants warm. One word of caution - the covers can also trap humidity which can be dangerous to plants in the winter time. Use stakes to keep the covers from touching the plants themselves and be sure to remove the covers during the daytime.

Did you know that plant matter releases heat as it decomposes? If you already have a pile of compost, consider moving it inside your greenhouse. Relocating the compost in the greenhouse will protect the material from the elements, keep it warmer, speed up the decomposition process, and raise the temperature of the greenhouse. The best location for the compost is in the middle of the greenhouse so that the entire space is warmed as the materials break down.

Have you ever heard of horticultural bubble wrap? It is a special type of bubble wrap made with large bubbles, treated with UV protection, and designed to wrap around a greenhouse. Attach a layer of horticultural bubble wrap to the interior walls of your greenhouse to block drafts and prevent heat loss. If you cannot get horticultural bubble wrap, traditional bubble wrap can work too.

Another option to keep your greenhouse warm is to install a heater. Garden centers carry space heaters specifically designed for greenhouses. If you have an electricity connection in your greenhouse, you can use an electric heater. However, propane heaters are a good option if you do not have electricity in your greenhouse. Just be sure to run a fan to distribute the warm air evenly throughout the space and allow for adequate ventilation as heaters present a risk of carbon monoxide build-up and overheating.

If you have tried all of these tips and are still wondering how to keep greenhouse warm in winter, it may be time for a renovation. Additions like blankets, heaters, and germination mats can only work so well if cold air is constantly coming in through the greenhouse walls. If this is the case for you, consider replacing the walls of your greenhouse with TUFTEX Multiwall Polycarbonate panels and roof of your greenhouse with Tuftex Corrugated Polycarbonate panels. Both of these Onduline materials provide excellent thermal insulation, are virtually unbreakable, are temperature resistant, and allow for high light transmission. They are also DIY-friendly because no special tools are required for installation. Tuftex Polycarbonate panels will help your plants stay warm and happy during the cold winter months. 

For more DIY inspiration and materials, visit the Onduline site today.