Overwintering tender plants, growing winter salad leaves and propagating next springs’ cuttings are just a few reasons for using your greenhouse over the coming months. By now you have no doubt taken down the shade netting and used liberal amounts of disinfectant to remove the risk of infection. Particularly important if your tomatoes succumbed to blight like so many growers this year.
Unless we experience extreme drops in temperature most greenhouses will remain frost free, but an additional layer of bubble insulation will help maintain the temperature at a more even level whilst still letting in the light. When choosing your bubble insulation there are a few things to consider, because all bubble insulation is created equal.
Go for a triple laminated bubble which has a solid sheet of film on each side of the insulating bubble layer. Many cheaper alternatives can be found online, but beware as these are more suitable as packaging as they are thinner and less robust. Missing the triple laminated layer means they trap less air, and subsequently will offer less insulating qualities.
Make sure that your insulation is UV resistant. This will extend the life of your bubble wrap which can be used winter after winter if handled carefully. Remember also to overlap the insulation on the vertical drops to avoid gaps and reduce any heat loss. When pinning or clipping it in place always start at the top and work down to get a flat finish with no gaps.
If you have a power source to your greenhouse then consider using tube heaters to help maintain temperatures at the appropriate level for your plants.
Standard tube heaters have a built in adjustable temperature level which controls the heat of the tube rather than the heat of the room. These will require manual adjustment according to fluctuations in the outside temperature. This type of heater is also designed to work with plug in thermostats to give a greater degree of control.
Tube heaters that have built in analogue or digital thermostats allow you to automatically set and maintain the temperature in the room. This removes the manual adjustments required by heaters that only feature a built in temperature control.
As with any heat source you need to take into account where they are placed for both safety and optimal effectiveness. The closer to the floor the better as the heat generated from these heaters will rise rather than be convected forwards into the greenhouse. Guards to prevent anything directly covering the heater and causing a fire risk should also be considered.