Preserve precious winter heat under glass without using fuel
This winter, consider bubble wrapping your greenhouse to protect plants and save cash by not using heating – here are some great tips from Greenhouses Direct.
In summer, your greenhouse is a fantastic energy converter. Sunlight streams in, and it warms up quickly. However, in winter, an unheated greenhouse loses heat quickly. There’s very little warmth from the sun, and there may be little or no direct sunlight. Without heating, what can you do to protect your tender plants from frost? Bubble wrap is a common solution, but for beginners, it can be a daunting task.
Why is bubble wrapping your greenhouse a good idea?
Add bubble wrap to provide a layer of insulation. It works like double glazing, with an air pocket between two layers of plastic (glass) to slow down heat/cold transfer. Don’t go for the ordinary packaging variety, and go for horticultural bubble wrap. This extra-thick wrap has bigger bubbles, too, which provide better insulation.
Packing bubble wrap offers little insulation and deteriorates when exposed to the elements and sunlight. Horticultural bubble wrap withstands UV damage and will last two-three years. It is important to consider the longevity whilst we all do our best to reduce our single-use plastics.
Using bubble wrap retains heat gathered during the day to prevent plants from being affected by frost at night. This insulation can increase the temperature inside by 1-2 °C. It’s a viable option to keep your greenhouse warm this winter.
How to bubble wrap a greenhouse
It is best done after the annual clean. Make sure all the glazing, nooks and crannies are clean, with no lurking pests and diseases. Let the greenhouse air dry after cleaning. Reduce moisture inside, as once the greenhouse is wrapped, you will lose access to windows and vents.
The best way to bubble wrap the greenhouse is to use long, continuous sheets. Cut and join as little as possible to reduce heat loss. Wrap horizontally from the door, around the greenhouse to meet the opposite side of the frame, starting at ground level. Secure the bubble wrap as you go with sticky tape or pegs that clip into the channels of the frame. It helps to have a willing assistant when wrapping the roof!
What to watch out for
There are pros and cons to this method – the most obvious con being a reduction in light. The bubble wrap acts as a diffuser, stopping direct sunlight and offering a much weaker light.
If you live in the north, where sunlight is very reduced in winter, you may decide to use extra lighting. Another consideration is that once wrapped, you will lose access to vents and windows. This means air cannot circulate as well, and excess moisture cannot leave.
This could cause problems with condensation, which can harbour moulds and encourage disease, so you do have to be vigilant. You can open the greenhouse door, but you’ll lose that hard-won heat.
If you are unsure of the benefits, there are alternatives to wrapping the whole greenhouse. Divide the greenhouse and insulate only one part. You can even insulate just one staging bench, creating a micro-environment. Clever use of propagators or cold frames within the greenhouse can help offer some protection. For other ways to increase the temperature in the greenhouse in an eco-friendly way, check out www.greenhousesdirect.co.uk.
